the southern pied babbler ( turdoides bicolor ) is a species of bird in the leiothrichidae family , found in dry savannah of botswana , namibia , south africa , and zimbabwe .

southern pied babbler

southern pied babbler <EOT> southern pied babbler ( turdoides bicolor ) is a species of bird in the leiothrichidae family .

chorus - call classification in the southern pied babbler : multiple call types given in overlapping contexts .

southern pied babbler nest with eggs , nylsvley area , south africa . [ photo warwick tarboton © ]

museum specimens indicate historical distributions . the map below shows locations from which museum specimens of southern pied babbler were collected . you can see more information on the individual museum specimens of southern pied babbler here .

nelson - flower , m . j . 2010 . kinship and its consequences in the cooperatively breeding southern pied babbler (

the pied babbler research project was established by me in 2003 and is based in the southern kalahari desert , south africa .

southern pied babblers , marakele national park , south africa . [ photo trevor hardaker © ]

pied babbler sentinel . image by alex thompson , cc by - sa 3 . 0 .

[ a southern pied babbler ( turdoides bicolor ) subordinate female immediately before dispersal to become dominant in a new group . dispersal is an important mechanism whereby southern pied babblers avoid inbreeding ; though there is no sex - bias in dispersal distance , individuals move twice as far from birth groups as from subsequent groups . southern pied babblers are found throughout the kalahari . . . [ show full abstract ]

golabek ka , radford an ( 2013 ) chorus - call classification in the southern pied babbler : multiple call types given in overlapping contexts . behaviour . pp . 1–22 .

nelson - flower mj ( 2010 ) kinship and its consequences in the cooperatively breeding southern pied babbler , turdoides bicolor cape town : university of cape town . 139 p .

humphries dj . 2013 . the mechanisms and function of social recognition in the cooperatively breeding southern pied babbler , turdoides bicolor . phd thesis , macquarie university , sydney , australia .

55 . engesser , s . , ridley , a . r . & townsend , s . w . 2016 . meaningful call combinations and compositional processing in the southern pied babbler .

[ 2 ] golabek k . 2011 . vocal communication and the facilitation of social behaviour in the southern pied babbler ( turdoides bicolor ) . phd thesis , university of bristol , bristol .

51 . ridley , a . r . 2016 . southern pied babblers : the dynamics of conflict and cooperation in a group living society . in

3 . ridley , a . r . & thompson , a . m . 2010 . dominatricks : reproductive conflict between female southern pied babblers .

happily for us there will be several presentations of our babbler research at the isbe conference in lund this year ( both pied and arabian babbler research ) . we look forward to presenting our babbler research to the behavioural ecology community . for a link to the isbe website , click

we welcome rute and robbie to the babbler project . both will be collecting data on pied babbler behaviour for several months over the summer breeding season and have done very will to learn the ropes so quickly .

ridley a , raihani n ( 2007 ) facultative response to a kleptoparasite by the cooperatively breeding pied babbler . behavioral ecology 18 : 324–330 .

a r ridley , a m thompson ( 2010 ) dominatricks : reproductive conflict between female southern pied babblers . africa birds & birding 15 , 30 - 34 [ magazine articles ]

distribution of southern pied babbler in southern africa , based on statistical smoothing of the records from first sa bird atlas project ( © animal demography unit , university of cape town ; smoothing by birgit erni and francesca little ) . colours range from dark blue ( most common ) through to yellow ( least common ) . see here for the latest distribution from the sabap2 .

du plessis , k . l . 2011 . heat tolerance of southern pied babblers in the kalahari desert - how will they respond to climate change ? msc thesis , university of cape town .

2 . ridley , a . r . & raihani , n . j . 2007 . facultative response to a kleptoparasite by the cooperatively breeding pied babbler .

the southern african bird atlas project ( sabap1 ) in namibia gathered a huge amount of distribution data between 1970 and 1993 .

may 2012 a new baby has been born to members of the pied babbler research community . congratulations to nichola and dave on the birth of their son joseph .

endemic to southern africa , where it is locally common in arid and semi - arid savanna woodland across northern namibia , botswana , zimbabwe and northern south africa . it is absent from more open habitats , such as that of the southern kalahari desert .

research on southern pied babblers was approved by the northern cape conservation authority and by the ethics committee , department of zoology , university of cape town ( aec no . 2006 / v15 / ar ) .

lyons , c . 2006 . the effect of environmental versus social factors on changes in territory size in the pied babbler . hons thesis , university of cape town .

a r ridley , n j raihani ( 2007 ) facultative response to a kleptoparasite by the cooperatively breeding pied babbler behavioral ecology 18 : 2 . 324 - 330 mar

24 . ridley , a . r . & thompson , a . m . 2011 . heterospecific egg destruction by wattled starlings and the impact on pied babbler reproductive success .

october 2012 a new baby has been born to members of the pied babbler research community ! congratulations to krys and neil on the birth of their beautiful baby son arun .

congratulations to sabrina engesser , who will also be joining the pied babbler research team this breeding season . sabrina won a phd scholarship to zurich university . we are delighted to have two new researchers join the pied babbler team ( james & sabrina ) , especially since dave humphries and alex thompson finished the fieldwork component of their phds this april !

nelson - flower mj , hockey par , o’ryan c , ridley ar ( 2012 ) inbreeding avoidance mechanisms : dispersal dynamics in cooperatively breeding southern pied babblers . journal of animal ecology 81 : 876–883 . pmid : 22471769

13 . radford , a . n . & ridley , a . r . 2008 . close - calling regulates spacing between foraging competitors in the group - living pied babbler .

[ 7 ] raihani n . j . & ridley a . r . 2008 . experimental evidence for teaching in the wild pied babbler . animal behaviour 75 : 3 - 11

58 . engesser , s . , ridley , a . r . & townsend , s . w . 2017 . element repetition rates encode functionally distinct information in pied babbler ‘clucks’ and ‘purrs’ .

april 2012 congratulations to james westrip , who will be joining the pied babbler research team this breeding season . james won a phd scholarship to edinburgh university and will be supervised by dr matt bell

[ 1 ] radford a . n . & ridley a . r . 2008 . close calling regulates spacing between foraging competitors in the group - living pied babbler . animal behaviour 75 : 519 - 527 .

my research interests are centred on avian social and breeding behaviour , and during the course of my phd ( supervised by dr . matt bell & dr . per smiseth ) i hope to investigate intra - and interspecific signalling and communication in the southern pied babbler . utilising playback and feeding experiments i aim to ascertain the amount of information use by babblers in a social context .

[ 11 ] ridley a . r . & raihani n . j . 2007 . facultative response to a kleptoparasite by the cooperatively breeding pied babbler . behavioural ecology , doi : 10 / 1093 / bebeco / ar1092

1 . ridley , a . r . 2006 . going gangbusters : group dynamics in pied babblers .

hockey par , dean wrj and ryan pg 2005 . roberts - birds of southern africa , viith ed . the trustees of the john voelcker bird book fund , cape town .

nelson - flower mj , hockey par , o ' ryan c , raihani nj , du plessis ma , ridley ar ( 2011 ) monogamous dominant pairs monopolize reproduction in the cooperatively breeding pied babbler . behavioral ecology 22 : 559–565 .

recently , i have been collaborating with mandy ridley to investigate the interspecific interactions that pied babblers have with other kalahari birds . to date this work has focused on cuckoo - host interactions between pied babblers and jacobin cuckoos (

collar , n . & robson , c . ( 2018 ) . southern pied babbler ( turdoides bicolor ) . in : del hoyo , j . , elliott , a . , sargatal , j . , christie , d . a . & de juana , e . ( eds . ) . handbook of the birds of the world alive . lynx edicions , barcelona . ( retrieved from urltoken on 9 july 2018 ) .

following this , i worked as a research assistant for dr mandy ridley at the pied babbler project ( 2011 - 2013 ) . i carried out playback experiments and collected and analysed sound data from individuals and groups , throughout the breeding seasons .

) are anything to go by , then pied babblers may live for more than 15 years in the wild .

raihani , n . j . 2008 . cooperation and conflict in pied babblers . phd thesis , cambridge university .

keynan , o . & yosef , r . 2010 . temporal changes and sexual differences of impaling behavior in southern grey shrike ( lanius meridionalis ) . behavioral processes 85 , 47 - 51 .

) over nest locations . more recently we have begun to investigate information transfer between pied babblers and scimitar - bills (

) , and the way in which pied babblers facultatively adjust their alarm calls to predators depending upon their reproductive stage .

graduated from the university of edinburgh in 2013 in zoology . she worked for eight months at the pied babbler research project , and is now studying biology , gender and philosophy independently while she figures out what to do next . blog coming soon at urltoken !

babbler with black bill , wings and tail . head and body are pure white , with brownish - black tail and wing . . .

36 . ridley , a . r . & van den heuvel , i . m . 2012 . is there a difference in reproductive performance between cooperative and non - cooperative species ? a southern african comparison .

25 . nelson - flower , m . j . , hockey , p . , o’ryan , c . raihani , n . , du plessis , m . & ridley , a . r . 2011 . monogamous dominant pairs monopolize reproduction in the cooperatively breeding pied babbler .

keynan , o . & yosef , r . 2010 . annual precipitation affects reproductive success of the southern grey shrike ( lanius meridionalis ) . the wilson journal of ornithology 122 ( 2 ) , 334 - 339 .

m j nelson - flower , p a r hockey , c o ' ryan , n j raihani , m a du plessis , a r ridley ( 2011 ) monogamous dominant pairs monopolize reproduction in the cooperatively breeding pied babbler behavioral ecology 22 : 3 . 559 - 565 may

ridley , a . r . 2003 . the causes and consequences of helping behaviour in the cooperatively breeding arabian babbler . phd thesis , cambridge university .

2016 . vocal cues to identity : pied babblers produce individually distinct but not stable loud calls . ethology 122 , 609 - 619 .

7 . ridley , a . r . & huyvaert , k . p . 2007 . sex - biased preferential care in the cooperatively breeding arabian babbler .

the reference for the information following is " roberts birds of southern africa " , 7th edition * edited by par hockey , wrj dean and pg ryan , published by " the trustees of the john voelcker bird book fund . "

comprehensive observations of pied babbler group life histories and breeding attempts were collected from july 2003 to may 2008 at the kuruman river reserve , south africa ( lat 26°58′s , long 21°49′e ) ( for information on climate and vegetation , see raihani and ridley 2007 ) . twenty - three wild pied babbler groups were habituated to the close presence of a human observer at a distance of 2–3 m , allowing observational data to be collected without disturbing natural behavior ( for habituation techniques , see ridley and raihani 2007a ) . each individual in the population was ringed with a unique combination of colored leg rings .

11 . raihani , n . j . & ridley , a . r . 2008 . experimental evidence for teaching in wild pied babblers .

we would like to thank prof tim clutton - brock , prof marta manser and the kuruman reserve trust for access to their land . we would like to thank the percy fitzpatrick institute of african ornithology for supporting the pied babbler research project . we would also like to thank martha nelson - flower for her genetic research on parentage in the pied babbler population . this work was also funded by a macquarie university studentship . we thank the northern cape conservation authority for research permits . ethical clearance was provided by the university of cape town and approved under ethics number r2012 / 2006 / v15 / ar .

introduction : southern pied babblers ( turdoides bicolor ) are resident in namibia especially in semi - arid to arid savannah woodland with corkwood or acacia trees . although they are usually observed in tall woodland , lower black thorn , camelthorn and kalahari woodland also attracts this species . this is a sociable bird that roost and interact territorially year - round in groups of up to 15 .

babbler research on uk quiz show qi ! june 2014 the uk quiz show , qi ( hosted by stephen fry ) , recently aired a show featuring one of our research questions ! we are very excited by this type of media coverage in the public domain ! here is a link to the youtube clip of this show : the mention of babbler research kicks in at about 5 min 40 secs ( and yes , that is one of our babbler pics that is featured in the background ! ) . urltoken

53 . keynan , o & ridley , a . r . 2016 . component , group and demographic allee effects in a cooperatively breeding bird species , the arabian babbler (

. . . importantly , even in high - skew societies where dominants successfully monopolize reproduction , conflict between dominants and subordinates may impose costs on dominant reproductive success . southern pied babbler subordinate females engage in reproductive competition only when there are unrelated , potential breeding partners present in their group because they do not breed with relatives or with extra - group males [ 14 , 15 ] . based on the infrequency with which such competition is successful , however ( in terms of parentage of young ) , subordinate females enter into reproductive competition far more often than expected . . . .

a r ridley , k p huyvaert ( 2007 ) sex - biased preferential care in the cooperatively breeding arabian babbler journal of evolutionary biology 20 : 4 . 1271 - 1276 jul

martha j . nelson - flower , phil a . r . hockey , colleen o ' ryan , nichola j . raihani , morné a . du plessis , amanda r . ridley ; monogamous dominant pairs monopolize reproduction in the cooperatively breeding pied babbler , behavioral ecology , volume 22 , issue 3 , 1 may 2011 , pages 559–565 , urltoken

i possess a great passion for scientific research and conservation . having interned at the pied babbler research project in 2009 , i jumped at the opportunity to study the behavioural and physiological effects of temperature on pied babblers for my master’s degree . this research was especially fascinating as it combined components of multiple disciplines ( climate change , avian biology , behavioural ecology , physiology , and conservation biology ) to answer conservation questions . my supervisors on this project included : amanda ridley , rowan martin , susan cunningham , and phil hockey .

january 2013 a new baby has been born to members of the babbler research community . congratulations to martha and tom on the arrival of their beautiful baby girl tess , a sister for audrey .

for my phd i will investigate the occurrence of call combinations in pied babblers ' vocal repertoire , under the supervision of dr . simon townsend . specifically , i am interested whether pied babblers combine meaningful call types into meaningful compositions and if there exist any rules governing the formation of such syntactic compositions . to do this , i will combine behavioural observations and audio recordings with playback experiments . i will further conduct artificial grammar playback experiments to probe what cognitive mechanisms underlie the production and perception of vocal compositions in pied babblers .

this is but a taster of the work that has been going on at babbler project over the years . if this article has sparked your interest , check out the project website for news and publications .

3 . raihani , n . j . & ridley , a . r . 2007 . adult vocalisations during provisioning : offspring responses and post - fledging benefits in wild pied babblers .

i am 35 years old , married to adi and father to mayan & yaara . i received my bsc . ( honors ) from haifa university in 2005 and my msc from tel aviv university in 2009 . my masters thesis was on the impaling behavior and male - female interactions in the southern grey shrike (

conference representation for the research group august 2015 the behaviour 2015 conference in tropical cairns has been and gone , and we had several group members giving talks there . lizzie gave a talk about her phd research into the effects of extreme heat on parental care strategies in pied babblers , ben gave a talk about his phd research into the effect of ontogeny on individual performance at a cognitive task in cooperative magpies , and mandy gave a talk on the theoretical and empirical evidence for adaptive benefits of kidnapping in the pied babbler . congrats to all group members for giving great talks at the conference !

here , we provide evidence of reproductive competition between dominant and subordinate females and its effects on dominant reproductive success and aggression in southern pied babblers . female subordinates participate in pre - breeding behaviours only when potential breeding partners are available . these competitive subordinate females decrease the reproductive success of the dominant females of their groups , and in some groups infanticide is observed . subordinate female reproductive competitors are also the target of increased aggression by dominant females during the fertile period . these conflicts over reproduction are generally expressed and resolved very early in the breeding cycle—an aspect of reproductive competition in cooperative breeders that has often been overlooked . this early manifestation of competition highlights the importance of using behavioural observations , as well as genetic data , when investigating reproductive competition and success . using genetic data alone strongly underestimates the effects of female–female reproductive competition in southern pied babblers because competition is so rarely successful . importantly , even in high - skew societies where dominants successfully monopolize reproduction , conflict between dominants and subordinates may impose costs on dominant reproductive success .

in many cooperatively breeding societies , females compete strongly with one another for the scarce resources needed to breed ; although sexual selection has traditionally been perceived as having a greater effect on males , such selection may act equally strongly on females [ 60 , 61 ] . in southern pied babblers , subordinate females with potential breeding partners compete intensely with dominants for access to breeding opportunities . in addition , females ( but not males ) aggressively oust one another from breeding positions [ 16 ] and aggression in juvenile females ( but not males ) is an important factor in successful adult dispersal [ 62 ] . here , sexual selection for traits ( such as aggression ) that improve female competitive ability may play a role not only in dispersal and acquisition of breeding positions , but also in infanticide , suppression of potential reproductive competitors , and eviction of such competitors from the group . we suggest that the behaviour of southern pied babblers provides further evidence that intense competition among females may result in the evolution of sexually specific traits ( reviewed in [ 63 , 64 ] ) .

july 2013 we have recently had a paper accepted into functional ecology . in this paper we look at the interspecific interaction between pied babblers and the solitarily foraging scimitarbill . we find that scimitarbills , who not have a reliable vigilance system of their own , regularly follow babbler groups and eavesdrop on the predator information that babbler sentinels provide . by so doing , scimitarbills gain significant benefits - they spend less time vigilant , more time foraging , and can utilise a greater diversity of foraging habitats than when alone . title : the ecological benefits of interceptive eavesdropping . authors : ridley , a . r . , wiley , e . m . & thompson , a . m .

[ 5 ] raihani n . j . & ridley a . r . 2007 . adult vocalizations during provisioning : offspring response and postfledgling benefits in wild pied babblers . animal behaviour 74 : 1303 - 1309

huge congrats to oded , who got his examiner reviews back today and passed his phd with no corrections requested ! well done dr keynan , well deserved indeed . for further info on oded ' s success , please refer to the pied babbler facebook page , as that page is updated more regularly . oded currenty has a number of ms in review , so we will update any of his future success here or on the facebook page .

july 2012 a locally extinct bird that has not been seen in the arava for 20 years , the nubian nightjar , was sighted by arabian babbler researchers recently . for a news article related to this significant and unusual sighting , click here

may 2018 we welcome to the team a new phd student , camilla , who will be starting her research on the pied babblers at the end of 2018 . more details on her research to follow shortly .

july 2012 happily , the eminently skilled and experienced elizabeth wiley ( aka lizzy ) will be rejoining the pied babbler research project this season as a senior research assistant . she will take primary responsibility of the research activities onsite for several months . lizzy spent the entire summer onsite last season , and we are ecstatic that she is joining the research group again . to find out more about lizzy , visit her profile on the ' researchers ' page .

august 2012 isbe lund 2012 is now over , and it was a great meeting . well done to all babbler researchers , whose presentations and posters went really well and generated a good amount of interest among members of the behavioural ecology community .

september 2012 our first babbler researcher of the season , elizabeth wiley ( lizzy ) , has just turned up at the study site - and so marks the beginning of the new data season ! hope its not too hot this summer . . .

december 2015 it ' s finally here ! the bbc documentary series , the world ' s sneakiest animals , will air in the uk on bbc two on christmas day . no word yet on when the international release will happen , but when i find out dates i will post it here . here is the link to the documentary series website . if you click on galleries , and then behind the scenes gallery , pic 8 of 9 is the pied babbler study site .

20 . raihani , n . j . , nelson - flower , m . j . , browning , l . e . & ridley , a . r . 2010 . routes to breeding in cooperatively breeding pied babblers .

n j raihani , m j nelson - flower , k a golabek , a r ridley ( 2010 ) routes to breeding in cooperatively breeding pied babblers turdoides bicolor journal of avian biology 41 : 6 . 681 - 686 nov

citation : humphries dj , finch fm , bell mbv , ridley ar ( 2015 ) calling where it counts : subordinate pied babblers target the audience of their vocal advertisements . plos one 10 ( 7 ) : e0130795 . urltoken

m j nelson - flower , p a r hockey , c o ' ryan , a r ridley ( 2012 ) inbreeding avoidance mechanisms : dispersal dynamics in cooperatively breeding pied babblers . journal of animal ecology 81 : 876 - 883

the ability to discriminate kinship has previously been demonstrated in avian species , which utilise vocal [ 40 – 43 ] , visual [ 44 – 46 ] , and olfactory signals [ 47 , 48 ] to recognise kin . by avoiding kin as mating partners , an individual can limit the potentially damaging effects of inbreeding depression among resultant offspring , and therefore improve reproductive success [ 30 , 49 ] . genetic analysis of parentage in the pied babbler has previously found that breeding between familiar relatives is rare and that they are therefore likely to have a mechanism of recognising familiar kin which they utilise to avoid inbreeding [ 13 ] . our observations further support the idea that pied babblers can recognise kin and behaviourally discriminate relatives in their environment .

12 . ridley , a . r . , raihani , n . j & nelson - flower , m . j . 2008 . the cost of being alone : the fate of floaters in a population of cooperatively breeding pied babblers .

winter is always a tough time for the pied babblers - a time when group composition changes dramatically due not only to mortality , but also to reproductive conflict and dispersal attempts prior to the breeding season . recently cgmx , the dominant female

n j raihani , a r ridley , l e browning , m j nelson - flower , s knowles ( 2008 ) juvenile female aggression in cooperatively breeding pied babblers : causes and contexts ethology 114 : 5 . 452 - 458 may

the first babbler babies of the season have arrived ! this is super - early in the breeding season for the babblers , but lizzy has brought news from the field that rnb have already fledged two young . this is possibly the youngest ever fledglings for a breeding season .

n j raihani , m j nelson - flower , k moyes , l e browning , a r ridley ( 2010 ) synchronous provisioning increases brood survival in cooperatively breeding pied babblers journal of animal ecology 79 : 1 . 44 - 52 jan

the arabian babbler project was established by prof amotz zahavi in 1974 and is based in the negev desert , israel . both projects have been running continuously since establishment and use detailed observations of habituated populations to gain an insight into the dynamics and evolution of group - living behaviour .

14 . raihani , n . j . , ridley , a . r . , browning , l . e . & nelson - flower , m . j . 2008 . juvenile female aggression in cooperatively breeding pied babblers : causes and contexts .

i have been collecting data on the causes and consequences of cooperative behaviour in pied babblers since 2003 . my current primary interests are : the causes of variation in contributions to cooperative care , the short - and long - term consequences of helping behaviour

humphries , d . j . , finch , f . m . , bell , m . b . v . & ridley , a . r . 2015 . calling where it counts : subordinate pied babblers target the audience of their vocal advertisements .

a r ridley , n j raihani , m j nelson - flower ( 2008 ) the cost of being alone : the fate of floaters in a population of cooperatively breeding pied babblers turdoides bicolor journal of avian biology 39 : 4 . 389 - 392 jul

abstract : eavesdropping behaviour can increase the total amount of information available to an individual and therefore has the potential to provide substantial benefits . recent research has suggested that some species are â€˜information giversâ€™ , particularly social species with cooperative vigilance systems , and that these species may consequently affect community structure by influencing the behaviour and niche utilization of other species . here , using behavioural observations and playback experiments , we compared the behavioural change in a solitary species ( the scimitarbill ) and a social species ( the pied babbler ) , to the presence and alarm calls of one another . our results revealed that scimitarbills underwent significant behavioural changes in the presence of social pied babblers : they reduced their vigilance rate by over 60 % , increased their foraging efficiency and expanded their niche by moving into open habitat and excavating subterranean food items . in contrast , pied babblers â€“ who have an effective intraspecific sentinel system â€“ did not show significant behavioural changes to the presence or alarm calls of scimitarbills . these results suggest that interspecific interceptive eavesdropping can provide significant benefits , influencing the behaviour and habitat utilization of eavesdropping species .

18 . raihani , n . j . , nelson - flower , m . j . , browning , l . e . , moyes , k . & ridley , a . r . 2010 . synchronous provisioning increases brood survival in cooperatively breeding pied babblers .

the pied babbler research project sits nestled in the heart of the kuruman river reserve in the northern cape , south africa . today , ten years since its conception , it remains under the principle leadership of associate professor amanda ridley of the university of western australia , who founded the project with the help of her field assistant ( and now research colleague ) , dr nichola raihani in 2003 . the project is a prolific international operation , with researchers coming from institutions in australia , switzerland , the united kingdom and south africa to study the babblers and their associated species .

january 2013 with the third flood of the season , it is safe to say that the drought has truly broken at the arabian babbler project . this is fantastic news , after many years of poor rain and low breeding success , this bodes well for a bumper breeding season in 2013 . fingers crossed !

an additional aspect of my research involves understanding interspecific interactions and communication . originally i started investigating these interactions between pied babblers and fork - tailed drongos . more recently , i have begun investigating interspecific interactions in scimitar - bills , yellow - billed hornbills and wattled starlings .

grateful thanks to tim clutton - brock , marta manser , staff at krr and all colleagues , students and assistants on the babbler project . thanks also to the kotzes and the de bruins , who allowed land access . t . p . flower and s . a . kingma as well as two anonymous reviewers provided valuable comments .

abstract : elaborate solicitation displays are a common feature of interactions between care - givers and offspring . these displays are interpreted as the phenotypic expression of the conflict of interests between parents and offspring over parental investment . offspring typically have siblings and thus do not exist in isolation . therefore , they may adjust their begging in response to their siblings ' begging , either competitively or cooperatively . alternatively , begging may be independent of the begging efforts of siblings . studies of avian begging have primarily focused on nestlings , where offspring are immobile and compete directly over the allocation of parental resources . we investigated the influence sibling begging had on individual fledgling begging in the cooperatively breeding pied babbler , turdoides bicolor . using experimental manipulations , we found that fledgling begging behaviour was negatively correlated with satiation and unrelated to the begging effort of siblings . pied babbler care - givers were able to target increased provisioning to individuals with artificially increased demand while maintaining provisioning rates to the rest of the brood . thus , fledglings were found to incur no provisioning costs or benefits from either increased or decreased begging by their siblings . we propose that the combination of targeted provisioning , flexible levels of provisioning and the dispersed nature of fledglings reduces the benefits of competitive or cooperative begging in this species .

may 2018 we have a number of pied babbler papers coming out in 2018 , all of which we think present really important findings . for full details of authors and titles , please see the publications tab . first up is the paper by nelson - flower et al in journal of animal ecology which tests prevailing hypotheses for the occurrence of cooperative breeding behaviour , and investigates the ecological and social contexts that influence dispersal decisions in pied babblers . second is the paper by nelson - flower et al in molecular ecology that looks at factors influencing reproductive skew , and finds different drivers of skew in males versus females . finally is the paper by wiley & ridley in ecology & evolution that looks at the pair bond as a predictor of reproductive success and group stability - a factor often overlooked in social species . all three of these papers used the long - term database to elucidate these behavioural trends - emphasising the value of long - term research !

this website provides information on the research my colleagues and i are currently conducting on pied and arabian babblers ( as well as other species these two ' focus ' species interact with ) . in these pages you will find details about our research , our study species , and any research opportunities currently available .

. . . pied babblers are a medium sized ( 75–95g ) passerine endemic to the kalahari , living in social groups of 2–15 individuals [ 31 ] . breeding within the social group is monopolised by a dominant pair [ 6 ] , and subordinate individuals will only achieve dominance within their natal territory if they can inherit vacant breeding positions without inbreeding [ 7 , 13 ] . prospecting in pied babblers is costly [ 22 ] , and long - term floating is rarely observed ( 80 . 0 % of prospectors return to their natal group within 30 days ; a . ridley , unpublished data ) . . . .

babbler society is highly dynamic - within our population we have evidence of eviction , divorce , infanticide and kidnapping . our long - term research suggests that these dramatic events are related to the continual struggle between group members for dominance and access to breeding opportunities . these struggles can sometimes result in a dominance overthrow or successful cuckoldry , but these events are relatively rare .

whilst others are foraging on the ground , often one babbler will take a higher position – up an acacia tree , say – and act as sentinel , watching for approaching for predators . while all is clear the watching babbler gives regular sentinel calls , which reassure the feeding birds that they can continue at ease , spreading out widely from each other without needing to look up as often to check for danger [ 3 ] . on sight of a predator , such as a mongoose or a pale chanting goshawk , the sentinel gives an alarm call that informs the rest of the group of the threat so that they can seek cover . the higher the predation risk in their environment , the more sentinel activity the babblers will undertake [ 4 ] .

. . . in red - winged fairywrens malurus elegans , females that have inherited a territory are more likely to seek egp , or seek egp from further away than females that have dispersed before breeding ( brouwer et al . , 2011 ) . similarly , superb fairy - wren malurus cyaneus , and pied babbler tur - doides bicolor females disperse further from their natal groups than non - natal groups ( cockburn et al . , 2003 ; nelson - flower et al . , 2012 ) . other potential rules may include discriminating against particular age groups likely to contain relatives , or based on previous mating experience , for example to avoid daughters of females that males previously mated with ( archie et al . , 2007 ) . . . .

in cooperatively breeding and other family living species , there are often more individuals of reproductive age than available breeding positions . asking how individuals attain reproductive status is therefore crucial if we are to understand the selection pressures that operate in these groups . here , we present data on routes to breeding in pied babblers turdoides bicolor , cooperatively . . . [ show full abstract ]

at the moment i am a second - year phd candidate in a joint supervision program ( cotutelle ) between tel aviv university , israel and macquarie university , sydney , australia , and i also work as the director of the arava birding center in the dead sea & arava science centre . my thesis title is " the effect of group size and composition on individual behaviour , group dynamics and population regulation in the arabian babbler (

one of the contexts in which loud - calling behaviour is observed is when the caller is in search of a mating partner , however , the calls are multi - functional and can be given in a wide range of contexts [ 34 ] . it is possible that the calling patterns we have observed are serving another function for the caller . for instance if the calls function for territorial defence , they may still occur at a higher frequency on boundaries with unrelated neighbouring groups . reduced aggression and a greater tolerance to related neighbours has been observed in a range of taxa including fish [ 50 ] , birds [ 51 ] , and mammals [ 52 – 55 ] . however , in the pied babbler territorial defence is usually undertaken as a group with all adult group members chorusing together [ 56 ] .

we have a fully - funded phd position based at the percy fitzpatrick institute , university of cape town , available . the position will be supervised by me ( amanda ridley ) , claire spottiswoode and susie cunningham . it would involve working with the babblers several months per year at our field site in the remote southern kalahari , and looks at the effects of group size on thermal tolerance limits , working on the hypothesis that in large groups , where each individual has to do less work , individuals will be better able to tolerate high temperatures . this phd combine behavioural ecology and physiological research . for more details , see : urltoken

) . to explore these relationships i conduct field experiments and observations on individual foraging success , foraging strategies and self versus social learning . together with this fieldwork i use the uniquely detailed 40 - year arabian babbler database to analyze long - term demographic effects . this database work involves finding what social or environmental factors promote group growth or extinction , and identifying critical group size effects in relation to eviction , dispersal and reproductive conflict behaviour .

with the help of a new research grant , i am beginning research on understanding long - term population dynamics in cooperative species , including factors that promote the expansion or extinction of groups . i will be using the long - term datasets of arabian and pied babblers to determine the influence of climatic changes ( heatwaves and droughts ) on social dynamics at both the group and population level

april 2012 unfortunately this year both our research populations have been hit by drought . in south africa the summer has now ended and after low rainfall over the rainy season pied babbler breeding success was very low . several of our groups failed to raise any young . our outstanding performers for the year were group xhosa , who bucked the trend and managed to raise five young to independence . in israel the breeding season is a few months in , and it is extremely dry ( oded reports only 7 mm of rain so far ) . many groups are still not breeding and it does not look like a promising breeding season . oded ( currently in - field ) brings happy news that one group currently has nestlings , and two groups have managed to fledge young - we ' ll cross our fingers that their fledglings manage to keep healthy .

our findings indicate that subordinates are maximising the potential of their loud - calling behaviour by using information regarding the composition of neighbouring groups . this information is likely to be obtained through several mechanisms . firstly , information may be exchanged during inter - group interactions . baboons , papio cynocephalus , use inter - group encounters to assess the number of opposite sex individuals within neighbouring groups [ 57 ] . pied babblers frequently engage in ritualised inter - group interactions and have many opportunities for information exchange [ 56 ] . during inter - group interactions , pied babblers often utilise sex - specific loud - calling behaviour [ 34 ] , which may provide a mechanism for assessing the number of opposite - sex individuals in neighbouring groups . secondly , information regarding the composition of neighbouring groups may be obtained from prospecting bouts , with information - gathering considered one of the primary functions of prospecting behaviour [ 58 , 59 ] . or thirdly , information may be gained through eavesdropping on neighbours [ 60 ] . great tits , parus major , are able to assess the quality of neighbouring males by eavesdropping on their calling behaviour [ 61 ] . eavesdropping may similarly provide a way of obtaining information about the composition of neighbouring groups in pied babblers .

here we have described how subordinate pied babblers , in addition to prospecting for breeding opportunities in the wider area [ 7 ] , also adopt a strategy of vocalising to neighbouring groups from within their natal territory . this strategy is maximised by using information regarding the composition of neighbouring groups to target an audience of potential breeding partners . importantly , subordinate loud - calling is not just given to any neighbouring group , nor focused towards the largest groups , but subordinate pied babblers are specifically targeting unrelated groups that contain a number of opposite sex individuals . our findings provide fresh insight into how subordinates within cooperatively breeding - societies , that are constrained in their opportunities to breed on the natal territory , appear to use information about the composition of neighbouring groups to inform the location of their vocal displays to target an audience of potential breeding partners .

august 2012 unfortunately , despite our high hopes , the drought in the negev desert resulted in a very poor breeding season for the arabian babbler population . although oded recorded a surprising amount of breeding activity given the dry conditions , very few of these young survived long enough to recruit to the adult population . there are now only a handful of juveniles around from the season ' s breeding activity , who face the struggle of making it through a difficult winter with little food around .

our findings that subordinate loud - calling behaviour is concentrated on the edges of territories , and specifically near to groups containing a number of unrelated , opposite sex individuals suggests that unsolicited loud - calling by subordinates functions for mate advertisement . importantly , it also suggests that pied babblers are capable of discriminating kinship and the number of potential mates within neighbouring groups , and can utilise this information to maximise the audience of their calling efforts .

june 2012 on the back of a dry summer with limited insect emergence , has come a very cold winter in the kalahari . tom , a research collaborator currently onsite working on drongo - babbler interactions , has reported that the babblers are suffering badly from the harsh combination of cold weather and limited food . many are steadily losing weight , and at this rate we can expect that some of our juveniles will not make it through their first winter . fingers crossed the toll will not be too high .

november 2012 finally some welcome rains have fallen at the arabian babbler study site ! after a very poor and very dry breeding season , flash floods have hit the arava . while these can be very dangerous in the short - term while they flow through the bone - dry river channels , they bring much needed water to a parched ecosystem , and are followed soon after by abundant germination . the picture to the right is a flash flood flowing along a wadi ( river channel ) that was previously completely dry .

february 2013 another breeding season has ended , but the tragedy this season was that it never really started . it was a scorching summer in the kalahari , but sadly for the animals , the rains never came . day after day of searing heat , but no rain respite made it the worst ever breeding season for the pied babblers . with very little food around , most groups did not bother to make any breeding attempts after december ( which was when the rains should have arrived ) . currently , we have only eight fledglings in the entire population . more groups did fledge young , but these have since been predated . seven of our groups have gone extinct , and with a harsh winter coming up , we expect more extinctions before the next breeding season starts . while this is a very sad event for us all at babbler project , on the bright side it is very interesting demographically , which helps us with the aims of our recent successful research grant !

one key focus of babbler research is their intelligent vocal capabilities . they communicate constantly using a diverse repertoire of sounds . whilst foraging for food , each individual gives low - pitch close calls , known as “chucks” to indicate its position to other group members . chuck calls function as a spacing regulator whilst foraging , so that individuals don’t encroach on each others’ feeding patches [ 1 ] . raising the pitch of the chuck a little tells the group that a large , shareable food source has been found [ 2 ] .

february 2018 i am delighted to announce that our latest research , on the effect of sociality on the evolution of intelligence , has been published in nature ! this work is from our study population that is the ' sister ' population to pied babblers : western australian magpies in perth . well done to phd student ben ashton on a great achievement . here is a media link to our article , including a clip of our research on the evening primetime news , here

phd submitted - congratulations to oded november 2014 congratulations to oded for submitting his phd thesis ! oded completed his phd thesis on individual and group dynamics in the cooperative breeding arabian babbler . oded has worked incredibly hard , and has produced a thesis to be proud of . each thesis submitted represents a huge amount of work by the student , and a lot of love and support from friends and family . oded and his family are returning back home soon , and they will be sorely missed from the friends they leave behind here in perth .

. . . unlike most birds , there is no sex - biased dispersal in pied babblers . females disperse slightly more often than males , but after accounting for the slight female - bias in the sex ratio , this higher rate is not signifi cant ( nelson - flower et al . 2012 ) . both males and females remain with their natal group as helpers for several years on average , and contribute to raising subsequent broods produced by the dominant pair . . . .

relatedness of mated and unmated pairs of opposite - sex adult pied babblers per year over 5 years of study . means ± standard error of the mean were generated from relatedness values calculated using the konovalov and heg ( 2008 ) algorithm within the program kingroup v2 _ 090218 ( konovalov et al . 2004 ) ; sample sizes are shown . a 2 - sample randomization / permutation test with 100 000 permutations within the program rundom pro 3 . 14 ( jadwiszczak 2009 ) was used to calculate significance

researchers have also discovered that babbler fledglings communicate with their parents non - vocally : in what is thought to be a display of blackmail , fledglings spend more time on the ground , where there is a higher risk of predation , than in the safety of trees when hungry . whilst on the ground , they are fed more by the foraging parents and helpers than when they are in the tree . thompson et al cite this as support for zahavi’s idea , that the fledglings risk their own mortality in order to attain higher provisioning rates by the parents [ 9 ] [ 10 ] .

we have recently had a manuscript accepted to global change biology . this manuscript , based on the msc fieldwork of kate du plessis , looks at the behavioural and body mass changes in pied babblers according to changes in temperature - the main focus of the paper is to investigate the potential ( sub - lethal ) effects of increasing temperature ( under predicted climate change ) on bird populations in semi - arid zones . congrats to the whole team ( kate was supervised by myself , phil hockey rowan martin & susie cunningham ) !

september 2012 it is with sadness that i announce the loss of a matriarch to the population , bmbo . originally from rainbow ( one of our first ever habituated groups ) , bmbo dispersed and founded her own group . her dispersal record remains the furthest that we have ever recorded a babbler dispersing within our study population . she founded the group called ngai tahu , and remained dominant from the start of the group three years ago until her recent disappearance . she is succeeded by her three daughters , one of whom may take the dominant female position ( she is unrelated to the current dominant male ) .

why do dominant females tolerate competitive subordinate females in their groups ? first , dominants may be able to moderate subordinate infanticidal activity through aggressive suppression during the fertile period ; such aggression is common when individuals are in reproductive conflict [ 4 , 9 , 11 , 18 , 24 – 27 ] . while there is no sufficient data to formally examine the relationship , a casual examination of current data appears to indicate a loosely inverse relationship between the amount of aggression observed and dominant female success . however , whether aggression occurs pre - emptively , or as a reaction to previous infanticide , or functions as another type of signal [ 52 ] is not clear . second , dominants may tolerate competitive subordinates because an additional helper substantially increases productivity in small babbler groups , reducing the high costs of breeding as a pair [ 31 ] . immigrant ( and completely unrelated ) subordinate females are very rarely found in large babbler groups ( m . j . nelson - flower 2008 , unpublished data ) , suggesting that when groups become large , these subordinates are either evicted by dominants or repelled if they attempt to immigrate , or that groups only become large when the absence of a competitor does not place limits on reproductive success .


the pinhead pearlfish , carapus boraborensis , is a species of slender , ray-finned fish in the family carapidae found in the tropical indo-pacific ocean ; it normally lives inside the body cavity of a sea cucumber such as the pineapple sea cucumber ( thelenota ananas ) or the leopard sea cucumber ( bohadschia argus ) .

pinhead pearlfish

pinhead pearlfish <EOT> @ firstdogonmoon the cucumber or pinhead pearlfish ! superb choice . some pearlfish also eat the cucumber ' s gonads . . . strange and stranger !

kate cranney on twitter : " @ firstdogonmoon the cucumber or pinhead pearlfish ! superb choice . some pearlfish also eat the cucumber ' s gonads . . . strange and stranger ! "

a small reddish - brown eel - like fish covered in fine dark speckles . the pinhead pearlfish lives within holothurians , and emerges through the cloacal opening of the sea cucumber at night .

some species of this family , however , are possibly parasitic . these live inside sea cucumbers where they will first eat the gonads of their host and then live inside the anal pore . the pinhead pearlfish ( carapus boraborensis ) is suspected to be parasitic whereas the silver pearlfish ( encheliophis homei ) is suspected to be non - parasitic based on stomach content analysis and where they are found within a cucumber when dissected .

( pacific pearlfish ) is found in the eastern pacific in the body cavity of cockles , pearl shells , and pen shells .

( bivalve pearlfish ) occurs in marine waters off western australia . it prefers to reside within sea cucumbers and the mantle cavity of bivalves

parmentier , e . and vandewalle , p . ( 2003 ) morphological adaptations of pearlfish ( carapidae ) to their various habitats . science publisher

before entry , a pearlfish will normally spend several minutes inspecting the entire body length of a cucumber before proceeding to the back end . a knocking or tapping movement is performed near the anus as if " asking " to gain entry . reports indicate that pearlfish normally back in tail first but have also been observed to enter head first . more than one pearlfish has been known to live inside a cucumber at any one time as well making for a somewhat cramped living environment . this trait has been observed with the silver pearlfish where sexual pairing has been found within a cucumber .

the great pearlfish , conqueror of sea cucumber bums , devourer of reproductive organs , all - around decent critter to anything but a sea cucumber .

( pearlfish ) is found in the western pacific on reefs . this fish lives in the body cavity of sea cucumbers by day and forages at night

this bizarre little fish lives inside the anus of a leopard sea cucumber ( bohadschia argus ) . i was filming a number of different fishes in the shallows , and only took a short clip of this sea cucumber . it wasn ' t until i looked at the footing that i saw the little pearlfish . pearlfish get their name from the members of their family that live inside oysters .

but the sea cucumber may not be entirely defenseless against the invasions of the pearlfish . some species have what could be functioning as a built - in gate in their anus — a handy accessory considering that in addition to the pearlfish , crabs and clams have also been known to make themselves at home inside the poor critters ( the sea cucumber , it seems , like any good host , can never really enjoy itself at its own party ) .

depending on what species it is , the pearlfish initiates one of two relationships once inside : a commensal one , in which it simply takes up space without either helping or adversely affecting the sea cucumber , or a rather more parasitic one , in which it chows down on its host’s gonads .

the pearlfish finds its reluctant host likely by smell , according to biologist eric parmentier of belgium’s university of liège . it then must choose the right end to enter , using its lateral line — sensory organs that detect movements in water — to home in on the outflow from the respiratory tree at the anus .

such pearlfishes come in a range of species , and don’t necessarily limit themselves to invading sea cucumbers . they’ll also work their way into sea stars , and are so named because they’ve been found dead inside oysters , completely coated in mother - of - pearl . beautiful , really , though i reckon the pearlfish would beg to differ .

pearlfish ( family carapidae ) are scaleless , their bodies are somewhat translucent , and they look remotely like eels when they swim outside of their host . they can be found in the atlantic , pacific and indian oceans and have been found down to depths of over 2 , 000 meters . some of the species can reach upwards of 50 cm in length when full grown .

ophidiiformes represent the " cusk eels " and some species within the family carapidae ( pearlfish ) live symbiotically within benthic invertebrates . the relationship of the fish to the host is quasi - parasitic ; only in a few cases is the parasitism overt . in most cases , the fish either consumes food that could be used by the host or , in most cases , simply takes up space

you’re breathing through your anus , by the way , and when you take a breath , the pearlfish strikes — squirming up your butt , making itself comfortable in your respiratory organ , and eating your gonads . or , they’ll go up in pairs and have sex in your body cavity . and that’s when you realize that you must have been a really awful human being in a past life . like , the type of person who talks on their phone in a movie theater kind of awful .

so like a disgraced samurai disemboweling himself , the sea cucumber gifts the world with its intestines , whether the world wants them or not . interestingly , though , the pearlfish doesn’t itself seem to trigger this reaction for reasons that aren’t yet clear . and it’s important to consider that the fish in fact benefits from the evisceration , because by using the sea cucumber as a home , it necessarily adopts its host’s predators . its survival depends on the sea cucumber’s ability to defend itself , which is quite intriguing from an evolutionary perspective .

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eel - like , moderate to shallow body depth ; maxilla free and movable ; cardiform teeth present ; branchiostegal membranes partly or completely united ; swim bladder with thin terminal membrane or bulb but no constriction ; lacking enlarged dentary or premaxillary fangs , dentary diastema , pelvic fins , and swim bladder rocker bone ; pectoral fins small , less than 29 % head length ; body thick , robust and highly pigmented ; 15 - 17 precaudal vertebrae .

uncommon species . shallows water of coral reefs . lives within holothurians ( e . g . thelenota ananas < \ i > , bohadschia argus < \ i > and stichopus chloronotus < \ i > ) .

indo - pacific : mauritius to the society islands , north to taiwan and the yaeyama islands ; including mariana and caroline islands .

greek , enchelys , = eel + greek , ophis = serpent ( ref . 45335 )

marine ; demersal ; depth range 1 - 150 m ( ref . 34024 ) . tropical

maturity : l m ? range ? - ? cm max length : 30 . 0 cm tl male / unsexed ; ( ref . 4104 )

dorsal soft rays ( total ) : 31 - 42 ; anal soft rays : 45 - 57 ; vertebrae : 119 - 126 . eel - like , moderate to shallow body depth ; maxilla free and movable ; cardiform teeth present ; branchiostegal membranes partly or completely united ; swim bladder with thin terminal membrane or bulb ; lacking enlarged dentary or premaxillary fangs , dentary diastema , pelvic fins , and swim bladder rocker bone ( ref . 34024 ) . pectoral fins small , less than 29 % head length ; body thick , robust and highly pigmented ( ref . 34024 ) .

uncommon species ( ref . 34024 ) . lives within holothurians ( e . g . thelenota ananas and bohadschia argus ) ( ref . 1602 ) .

nielsen , j . g . , d . m . cohen , d . f . markle and c . r . robins , 1999 . ophidiiform fishes of the world ( order ophidiiformes ) . an annotated and illustrated catalogue of pearlfishes , cusk - eels , brotulas and other ophidiiform fishes known to date . fao fish . synop . 125 ( 18 ) : 178p . rome : fao . ( ref . 34024 )

) : 23 . 6 - 28 . 9 , mean 27 . 5 ( based on 920 cells ) . phylogenetic diversity index ( ref .

bayesian length - weight : a = 0 . 00102 ( 0 . 00046 - 0 . 00225 ) , b = 3 . 06 ( 2 . 88 - 3 . 24 ) , in cm total length , based on all lwr estimates for this body shape ( ref .

html public " - / / w3c / / dtd xhtml 1 . 0 strict / / en " " urltoken "

picture of carapus boraborensis has been licensed under a creative commons attribution - noncommercial . original source : fishbase permission : some rights reserved

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project noah is a tool to explore and document wildlife and a platform to harness the power of citizen scientists everywhere .

lady elliot island ' s shallow coral lagoon , in the coral sea at the south end of the great barrier reef .

i know . it lives in a sea cucumber bottom ! from what i ' ve read the sea cucumber is not getting anything out of the " relationship " . nature , weirder than anything we can imagine . the video i put up at youtube is a too cropped . i ' ll see if i can fix that so you can see the fish better .

marine ; demersal ; depth range 1 - 150 m ( ref . 34024 ) . tropical , preferred ?

confused by a class within a class or an order within an order ? please see our brief essay .

to cite this page : myers , p . , r . espinosa , c . s . parr , t . jones , g . s . hammond , and t . a . dewey . 2018 . the animal diversity web ( online ) . accessed at https : / / animaldiversity . org .

disclaimer : the animal diversity web is an educational resource written largely by and for college students . adw doesn ' t cover all species in the world , nor does it include all the latest scientific information about organisms we describe . though we edit our accounts for accuracy , we cannot guarantee all information in those accounts . while adw staff and contributors provide references to books and websites that we believe are reputable , we cannot necessarily endorse the contents of references beyond our control .

this material is based upon work supported by the national science foundation grants drl 0089283 , drl 0628151 , due 0633095 , drl 0918590 , and due 1122742 . additional support has come from the marisla foundation , um college of literature , science , and the arts , museum of zoology , and information and technology services .

html public " - / / w3c / / dtd xhtml 1 . 0 transitional / / en " " urltoken "

these fish are unique in that the adults normally live inside invertebrates like clams , sea squirts , and starfish in a commensal relationship ( not harming their host ) . this trait is common throughout the carapidae family .

this pairing behavior is not often seen in our reef aquariums but occasionally members of various reefkeeping forums will report that they have one in their tank .

watch the video below to see this relationship . if you ' re short on time , skip ahead to the 6 minute mark for the re - entry . . .

shane has kept saltwater tanks for the last 12 years , is a research scientist , lives in northern indiana , and is a proud advanced aquarist staffer .

copyright © 2002 - 2018 by pomacanthus publications , llc , all rights reserved .

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what is your favourite australian fish @ firstdogonmoon ? ! i ' m curious . . . . and often impressed by your use of cartoonal binomial nomenclature .

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phylogenetic diversity index ( ref . 82805 ) : pd 50 = 0 . 5078 [ uniqueness , from 0 . 5 = low to 2 . 0 = high ] .

bayesian length - weight : a = 0 . 00102 ( 0 . 00046 - 0 . 00225 ) , b = 3 . 06 ( 2 . 88 - 3 . 24 ) , in cm total length , based on all lwr estimates for this body shape ( ref . 93245 ) .

trophic level ( ref . 69278 ) : 3 . 4 ±0 . 3 se ; based on size and trophs of closest relatives

vulnerability ( ref . 59153 ) : low vulnerability ( 16 of 100 ) .

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conceived and designed the experiments : oh fl . performed the experiments : oh . analyzed the data : oh fl . contributed reagents / materials / analysis tools : fl . wrote the paper : oh fl . obtained permission for animal experiments : fl .

this is an open - access article distributed under the terms of the creative commons attribution license , which permits unrestricted use , distribution , and reproduction in any medium , provided the original author and source are properly credited .

data on sex - specific differences in sound production , acoustic behaviour and hearing abilities in fishes are rare . representatives of numerous catfish families are known to produce sounds in agonistic contexts ( intraspecific aggression and interspecific disturbance situations ) using their pectoral fins . the present study investigates differences in agonistic behaviour , sound production and hearing abilities in males and females of a callichthyid catfish .

current data demonstrate that both male and female m . thoracata produce aggressive sounds , but the behavioural contexts and sound characteristics differ between sexes . sexes do not differ in hearing , but it remains to be clarified if this is a general pattern among fish . this is the first study to describe sex - specific differences in agonistic behaviour in fishes .

a wealth of information is available on sound - generating mechanisms , sound production during agonistic and reproductive behaviour , and hearing in fishes ( for reviews see [ 1 – 5 ] ) . despite this knowledge , data on sex - specific differences in sonic organs , sound production and in hearing are very limited [ 6 ] .

a previous study on the callichthyid armoured catfish megalechis thoracata ( formerly hoplosternum thoracatum ) showed that , corresponding to the behavioural contexts , males and females uttered different types of pectoral sounds [ 27 ] . this differs considerably from investigations on the callichthyid c . paleatus , in which males produced trains of sounds during dyadic contests , whereas no stridulation sounds could be recorded from females during social interactions [ 13 , 28 ] .

acoustic communication is defined as transmission of information by a sender to a receiver with benefits for the receiver or mutual potential benefits for both [ 36 ] . accordingly , a match of spectral contents of sounds and best hearing sensitivity of the intended receiver , and vice versa , should be preferred by natural selection [ 33 , 35 ] . auditory sensitivity was found to match the characteristics of sounds produced in the frequency domain in some species [ 35 , 37 – 41 ] , but mismatch was observed in others [ 33 , 42 ] .

the aims of the present study were to investigate sex - specific differences in ( 1 ) sound - generating mechanisms , ( 2 ) agonistic behaviour , ( 3 ) sounds produced and their characteristics , ( 4 ) the auditory abilities , and finally ( 5 ) to determine if the dominant frequencies of sounds correlate with the best hearing sensitivity in the callichthyid catfish m . thoracata .

experiments were performed with permission of the austrian federal ministry of science and research ( bundesministerium für wissenschaft und forschung , gz 66 . 006 / 0023 - ii / 10b / 2008 ) . the permission covered all experimental procedures . no animal was sacrificed during this study . according to the austrian law on experiments in animals ( tierversuchsgesetz 1989 / 2005 ) an institutional animal care and use committee ( or ethics committee ) was not mandatory and did not exist at the university of vienna when experiments were carried out .

seventeen specimens of m . thoracata were used for the study : seven subadult males ( 93–104 mm total length , tl , 12 . 2–19 . 1 g body mass ) , nine subadult females ( 84–102 mm , 9 . 8–17 . 1 g ) and one adult male ( 126 mm , 32 . 9 g ) . fish were obtained from a local pet shop and a fish farmer . we assume that 16 of the 17 fish were subadult because they were one year old during our experiments and mayr [ 27 ] stated that first reproductive behaviour in this species is shown at the age of two years . moreover , we observed no reproductive behaviour in the present study when sexes were kept together in community tanks . this species is a bottom - dwelling fish from slowly flowing rivers , pools , drainage ditches and swampy areas in south america [ 43 ] .

the sex of the fish was determined by inspecting the genital papillae , the distance between coracoids and the size of pectoral fins . males possess genital papillae , a narrower gap between coracoids and longer , thicker and orange pectoral spines [ 43 ] . due to the individually spotted body pattern , the subjects could be easily distinguished from each other .

fish were kept in three community tanks ( 110 x 30 x 55 cm ) whose bottom was covered with fine sand and which were similarly equipped with half flower pots , tubes , plants and roots as shelters . the tank of the adult male measured 90 x 30 x 30 cm . four males and four females and three males and five females , respectively , were kept together . a 12 : 12 hour light : dark cycle was provided and the water temperature was kept at 25 ± 1°c . the aquaria were filtered by external filters in order to reduce noise . fish were fed frozen chironomid larvae and occasionally artificial food ( flakes and tablets ) five to six times a week .

after behaviour and sound recordings , body mass , total length and length of the pectoral spine of each contestant were measured . the pectoral spine length ( psl ) was measured from the juncture of the spine with the outer body surface to its tip using digital callipers . the relative pectoral spine length ( rpsl ) was calculated using the formula rpsl = psl / tl , where tl is the total length .

all agonistic experiments were performed from august to november 2011 . fish were kept for three months in holding tanks before the start of behavioural experiments . the video and sound recordings were carried out in a walk - in soundproof room , which was constructed as a faraday cage . the experiments were conducted in a test tank ( 70 x 40 x 35 cm ) . the resonant frequency of the tank is 3042 hz according to akamatsu et al . [ 44 ] . the water temperature was maintained at 25 ± 1°c . the test tank was placed on a table that rested on a vibration - isolated concrete plate .

the behaviour and acoustic signals were recorded using a hydrophone ( brüel & kjaer 8101 , sensitivity −184 db re 1 v μpa −1 ) , which was connected to a power supply ( brüel & kjaer 2804 ) and placed in the centre of the aquarium close to the back wall . both the hydrophone and video camera ( sony ccd - vx1e ) were connected to a hifi s - vhs video cassette recorder ( jvc hr - s4700 eg / e ) . hifi audio and s - video signals were stored simultaneously on s - vhs hifi videotapes ( fujifilm super vhs pro se - 240 ) . sound pressure levels ( rms fast time weighting , linear frequency weighting ) were measured in parallel with the sound recordings using a sound level meter ( brüel & kjaer mediator 2238 ) connected to the power supply . the observer was always hidden behind a curtain during recordings . external filters of the test tank were switched off before the start of experiments .

as the intention of this study was to record acoustic displays during agonistic behaviour dyadic interactions were not allowed to proceed to a phase , where biting might have occurred . no biting or injuries were observed in any of the experiments .

each sound was digitized using a sampling rate of 11 khz ( 16 bit resolution ) and analysed using cool edit 2000 ( syntrillium software corporation , phoenix , usa ) and st x soundtools 3 . 7 . 8 . ( institute of sound research at the austrian academy of sciences , vienna ) . only sounds with a good signal - to - noise ratio were analysed . the following acoustic variables were measured from sounds recorded during dyadic contests :

sound duration ( sd ) : the total length between the onset and the end of a single call or a series of sounds . dominant frequency ( df ) : the frequency with the highest amplitude within a power spectrum . the dominant frequency of sounds was determined from cepstrum - smoothed power spectra . harmonic sounds are characterized by several regularly spaced peaks , in which the frequencies of the harmonic peaks are multiples of that of the fundamental frequency . the harmonic content of a sound was controlled by overlaying a harmonic grid .

sound pressure level ( spl ) : measured in db re 1μpa ( rms fast , linear weighting ) . in order to compensate the varying distances of vocalizing fish to the hydrophone , a correction factor was calculated . therefore , the test tank was divided into 21 sectors ( each measuring 10 x 10 cm ) by using a grid applied on the front glass of the aquarium . the sector in which a fish emitted sounds was noted . because sounds of m . thoracata were of low energy , pink noise was chosen for calculating a correction factor . short tone bursts were played back at a constant spl from a small loudspeaker ( fuji 7g06 , 8 ohm , 0 . 8 w ) , in each of the 21 sectors , and the spls were noted . the relative difference of the spl measured in the sector nearest to the hydrophone ( 3 cm away ) and the other sectors were calculated and added to the spl values of fish sounds measured before . thus , a distance - independent absolute spl value could be determined for each sound emission .

the aim of the behavioural analyses was to describe all behavioural patterns ( elements ) occurring during the male - male and female - female agonistic contests . all behavioural patterns shown during a total of 24 agonistic encounters were classified according to the description presented in

. the number of acoustic signals and visual displays such as attack , circling and head nodding was counted for each experiment and individual .

description of the behavioural repertoire shown during dyadic male - male and female - female interactions of m . thoracata .

fin displaying or approaching another fish , stopping suddenly before forcefully hitting the other with its tail .

two females swam in an anti - parallel ( head - to - tail ) orientation .

two males moved towards each other , in a parallel , anti - parallel position or various angles spreading all their fins . additionally , at high intensities the caudal part of the body was erected in a distinct angle .

continued escape reaction in response to a chase . fish swam rapidly away from the aggressor .

females showed serial vertical up and down movements of their heads in different positions to each other .

males moved their heads rapidly away and towards the opponent while bending their body c - like .

one female following the opponent by a snake - like movement on the bottom .

definitions followed mayr [ 27 ] except for fin beating , jerks and sneaking . m—males , f—females .

auditory sensitivity was determined using the non - invasive auditory evoked potential ( aep ) recording technique , originally reported by kenyon et al . [ 45 ] and modified by wysocki and ladich [ 46 – 47 ] .

for each test condition , the stimuli were presented at opposite polarities ( 180° phase shifted ) and the corresponding aeps were averaged in order to eliminate stimulus artefacts . at spls close to the threshold , this procedure was performed at least twice and the aep traces were overlaid to examine if they were repeatable . the spl values of tone burst stimuli were reduced in 4 db steps . by overlaying replicate traces , the lowest spl in which an identifiable and repeatable aep trace could be obtained was regarded as threshold . the method developed by kenyon et al . [ 45 ] gives auditory thresholds very similar to behavioural thresholds ( for discussion see [ 4 , 48 ] ) .

additionally , a one - way analysis of variance ( anova ) was performed , followed by a bonferroni post - hoc test , in order to determine differences in sound characteristics of each aggressive sound type . differences in relative pectoral spine length between sexes were tested using a paired t - test . a total of 244 sounds were analysed .

mean hearing thresholds were determined for both sexes at each frequency . thresholds obtained for males ( n = 6 ) and females ( n = 6 ) were compared by a two - way anova using a general linear model , where one factor was sex and the other was frequency . the sex factor alone should reveal differences in sensitivity between sexes and , combined with the frequency factor , if different tendencies exist at different frequencies of the audiograms .

all statistical tests were conducted using pasw 18 . 0 ( spss inc . , chicago , usa ) . the significance level was set at p ≤ 0 . 05 .

produced sounds by vibrating pectoral fins . the first pectoral fin rays were orange in males in contrast to females . pectoral spines were longer and thicker in males . the relative length of pectoral spines ( pectoral spine length / total length ) was on overage 1 . 7 - fold higher in males than females ( t - test , t = 44 . 27 , df = 15 , p ≤ 0 . 01 ) (

different letters indicate statistically significant differences between sexes . psl—total length of pectoral spine , tl—total fish length .

aggressive interactions usually started after removal of the separating sheet and as soon as opponents detected each other visually . the agonistic behavioural sequences were interrupted by air gulping , digging , resting close to each other or withdrawal into the shelter . for the description of behavioural patterns observed during thirteen male - male and eleven female - female encounters see

generally , one or both males started to approach each other and erected their fins ( threatening fin display ) . occasionally , this posture was followed by fin beating , which could last for several seconds . head jerking followed and was accompanied by the production of two sound types , namely barks or thumps , indicating high levels of aggression . jerking could occur without sound emission , in which case maximally three jerks were observed .

in 12 out of 13 encounters ( 92 % ) , barks and thumps were produced during aggressive interactions . furthermore , in 10 out of 13 contests ( 78 % ) , sound emission occurred in both contestants . barks were emitted at various distances from a few centimetres up to a maximum of 40 cm away from the opponent . before abduction of pectoral fins , a single adduction was observed . barks were often produced during approaching and swimming (

) . the individual producing a sound mostly swam away and then again approached the conspecific . the latter could react by fin displays or moving away from the other .

the illustration shows the right male approaching the opponent , shortly before uttering a bark .

in contrast to barks , thumps occurred only in direct proximity ( within one body length ) to the opponent . typically , opponents showed fin displays in a parallel , anti - parallel position or at various angles to each other (

) , or swam close and emitted thumps . typically , thumps were produced in an oblique position towards the opponent . opponents responded by producing a thump , by attacking or by fleeing .

this screen shot shows the typically threatening fin display with fins spread and the caudal part of the right male erected in a distinct angle . the right fish produced a thump in this oblique anti - parallel position relative to the conspecific .

during all experiments , we counted a total of 40 attacks , often preceded by fin display and fin beating . attacks were mainly performed by sound producers , occasionally accompanied by thumps . besides these behavioural elements , chasing was observed . during chasing , barks were emitted by the pursuer .

in five out of seven experiments , barks were even emitted after separating both fishes by the plastic sheet , i . e . after they lost visual contact . barks were recorded mainly in males , which produced numerous sounds during the dyadic contests . just in one case did both opponents emit barks . after separation by the plastic sheet , males generated barks during swimming or when approaching the separating sheet .

) close to the bottom . this sneaking behaviour toward the opponent was occasionally accompanied by the emission of crackles . sounds were recorded in all female - female experiments . in four out of eleven contests , both females vocalized during agonistic interactions . sounds were produced close to the opponent ( within one to two body lengths ) (

) and were generated by rapid pectoral fin movements . shortly before uttering a crackle , the vocalizing fish may strike towards the opponent . crackles were most frequently emitted when one female chased the other . swimming after each other or pursuing could continue into circling behaviour (

) , which lasted up to 3 s . sounds were uttered before , during or at the end of circling .

head nodding was either performed by one female or simultaneously by both . two to 18 head nods per individual were observed within a series . we counted a total of 736 head nods during eleven agonistic interactions , and the vocalizing female exhibited a higher rate . this visual threatening display could be elicited by the movement of one fish , when swimming by or when above the other , before and after circling , and when resting close to each other . furthermore , interactions were characterized by a high rate of body contacts such as touching with barbels . attacks occurred only four times : three were accompanied by crackles and one was exhibited shortly after head nodding .

in contrast to male - male encounters , in which both males vocalized , crackles were mainly produced by one female , seldom by both . female - female contests were characterized by circling behaviour and the lack of jerks . head nodding could not be observed in any male - male interaction . while males beat their fins during fin displays , females did it during circling . females undulated only their dorsal and caudal fins , whereas in males all fins were involved . furthermore , females attacked less frequently than males , indicating a lower level of aggressivity .

three types of sounds were recorded during dyadic encounters . males produced barks and thumps , and females emitted crackles . barks and thumps were recorded in seven out of eight males and crackles in eight out of nine females . the fish produced 376 barks , 66 thumps and 739 crackles during 24 interactions . acoustic signals were not audible to human listeners . video analysis revealed that barks were produced during abduction of the pectoral fin . we could not unequivocally determine the movement of the pectoral fins ( adduction and / or abduction ) during the emission of thumps and crackles .

barks were low - frequency harmonic sounds showing frequency modulation ; they only occurred singly . they consisted of one to three parts and were therefore classified as being mono - , bi - or tripartite (

) . sound duration ranged from 159 to 317 ms , and the spl ranged from 101 . 2 to 125 db re 1 μpa at a distance of 3 cm . the main energies were found in the first , second or third harmonic . the dominant frequency of bipartite barks varied in the first part from 110 to 600 hz , and in the second from 170 to 730 hz .

the spectrum shows three harmonics ( 1st , 2nd , 3rd ) with the highest energy found in the second harmonic . sampling rate 22 khz . hanning filter , overlap 75 % , ( a ) filter bandwidth 20 hz , ( b ) filter bandwidth 1 hz , number of coefficients 350 .

the spectrum reveals three harmonics ( 1st , 2nd , 3rd ) within the second sound part ( white arrow ) with the highest energy found in the second harmonic . the oscillogram shows lower amplitude in the first part ( light blue arrow ) . sampling rate 11 khz . hanning filter , overlap 75 % , ( a ) filter bandwidth 20 hz , ( b ) filter bandwidth 1 hz , number of coefficients 170 .

thumps were produced singly and showed no harmonic structure . they were mostly mono - , seldom bipartite (

) . bipartite thumps were recorded only in the one examined adult subject . sound duration ranged from 116 to 446 ms and the spl ranged from 107 . 07 to 137 . 5 db re 1 μpa . the dominant frequency varied from 70 to 210 hz .

the dominant frequency is indicated in ( b ) . sampling rate 11 khz . hanning filter , overlap 75 % , ( a ) filter bandwidth 20 hz , ( b ) filter bandwidth 1 hz , number of coefficients 80 .

female crackles differed from male sounds in their complex structure and frequency content . they were of higher frequency and always consisted of series of sound elements (

) . crackles were built up mostly by four sound elements ( range : 2–8 elements ) . these series were characterized by a main element featuring the highest peak - to - peak - amplitude and several elements of lower amplitude before and after the main element (

) . elements could be separated by intervals from each other and could consist of a substructure such as a train of pulses ( = one element ) .

the oscillogram shows five sound elements . the white arrow indicates the main element , followed by a train of pulses . the dominant frequency is indicated in the cepstrum - smoothed power spectrum in ( b ) . sampling rate 11 khz . hanning filter , overlap 75 % , ( a ) filter bandwidth 100 hz , ( b ) filter bandwidth 1 hz , number of coefficients 20 .

the duration of crackles ranged from 81 to 394 ms . single elements ( including train of pulses ) ranged from 5 . 6 up to 192 . 9 ms and main elements varied from 15 . 3 to 57 . 6 ms in duration . spls were between 101 . 5 and 128 . 1 db re 1 μpa . dominant frequencies of crackles varied from 370 to 830 hz .

) . thumps were significantly louder than barks and crackles , but no such difference was found between barks and crackles ( bonferroni post - hoc test ) . furthermore , the dominant frequencies varied between sound types ( one - way anova : f

) . mean dominant frequencies of crackles were much higher than of other sound types . the first part of barks and thumps did not differ significantly in dominant frequency ( bonferroni post - hoc test ) .

mean ( + se ) sound duration of male barks and thumps ( n = 7 ) and of female crackles ( n = 8 ) .

mean ( + se ) sound pressure level of male barks and thumps ( n = 7 ) and of female crackles ( n = 8 ) .

mean ( + se ) dominant frequency of male barks and thumps ( n = 7 ) and of female crackles ( n = 8 ) .

sound characteristics of male barks and thumps and female crackles were significantly correlated to morphological measures when males and females were pooled . duration of male thumps and female crackles combined increased with mean total length and pectoral spine length (

correlations between mean sound characteristics ( sound duration , dominant frequency , sound pressure level ) of male and female sound types and morphological variables ( total length , pectoral spine length , relative pectoral spine length ) .

n = 15 . b—bark , bp—bark part , c—crackles , t—thumps . pearson’s correlation coefficients are given . asterisks indicate statistically significant differences .

) . individuals with larger pectoral spines emitted sounds of lower frequency . mean dominant frequencies of the first part of barks ( or the second part of barks ) , or of thumps and females crackles combined , were negatively correlated to pectoral spine lengths (

thus , mean sound characteristics were always correlated to relative pectoral spine lengths , except for spls of male barks . in contrast , only sound duration and spls of thumps and crackles combined were correlated to total length (

all fish detected tone bursts between 100 hz and 4 khz . hearing curves of both sexes were u - shaped with best auditory sensitivities between 0 . 2 and 1 khz (

) . hearing abilities decreased rapidly above 1 khz . thresholds increased by 41 db between 1 and 4 khz in males and females . overall , hearing thresholds did not differ between sexes ( two - way anova : f

= 1 . 2 , n . s . ) . females had better hearing between 0 . 1 and 1 khz ( two - way anova : f

= 0 . 007 , n . s . ) . no significant interaction was found between sex and frequency . thus , the difference in auditory sensitivity between 0 . 1 and 1 khz was not frequency - dependent .

mean ( ± se ) auditory sensitivities of male ( n = 6 ) and female ( n = 6 ) m . thoracata .

) . the greatest energy of sounds was concentrated from 180 to 620 hz in male barks , from 100 to 540 hz in male thumps and from 470 to 750 hz in female crackles . main energies of male and female sounds were much lower than the resonant frequency of the test tank ( see energy peak at 3 khz in

( solid lines ) in relation to spectral characteristics of sounds ( dotted lines ) .

power spectra of sounds were averaged of sounds of all individuals and are shown in relative amplitude values ( right y - axis ) .

video analysis revealed that both sexes of m . thoracata produced sounds during rapid pectoral fin movements . therefore , we assume that sound production is based on a stridulatory mechanism , well known in numerous catfish families [ 50 ] . while we observed that male barks were produced during abduction of pectoral fins , the movement of pectoral spines during generation of thumps and crackles remains unclear due to faster movements of fins and technical limitations of a standard video recording system . pruzsinszky and ladich [ 13 ] mentioned that c . paleatus produced sounds by abducting the pectoral fins alternately . similarly , heyd and pfeiffer [ 51 ] reported that in the callichthyid catfish d . urostriatum sounds were produced during abduction , and all members of the family callichthyidae probably generate sounds during abduction of pectoral fins . we assume that barks and thumps are generated by a single pectoral fin abduction and crackles by several fin abductions depending on the number of elements within a crackle sound .

the current study revealed that agonistic behaviour of male and female m . thoracata differed from each other . male agonistic behaviour mainly consisted of fin displays and jerks , whereas female behaviour was characterized by circling , head nodding , sneaking and striking . agonistic sounds were produced by males and females in different behavioural contexts . while males uttered thumps during threatening displays and barks mostly during approaching and swimming , females , in contrast , emitted crackles mainly during chasing behaviour . threatening displays in males consisted of a sequence of visual displays shown by both opponents , during which both may produce sounds . in contrast , chasing behaviour in females was typically shown in one individual , which vocalized when following or moving toward the other fish .

based on the present data , male m . thoracata seem to be more aggressive than females as revealed by the much higher number of attacks ( 40 in males versus four in females ) observed during a similar number of same - sex contests . the vocalizing behaviour of m . thoracata differs markedly from the closely related callichthyine subfamily member c . paleatus , in which only males produced trains of sounds during courtship and in which aggressive behaviour was absent during dyadic contests [ 13 ] . kaatz and lobel [ 56 ] mentioned that male corydoras spp . emitted agonistic chase sound only before , during and after spawning . this difference between the genera corydoras and megalechis is primarily due to their different mating systems . male megalechis are territorial and defend nest sites , while male corydoras do not build nests or show parental care .

the observation that fin beating and sound production occurred at short distances to the opponent indicates that water movement may be detected by the lateral line . this may constitute a third communication channel besides the visual and acoustic ones . such hydrodynamic cues are potentially involved in all short - distance agonistic and reproductive activities in fishes but seldom unequivocally proven . satou et al . [ 58 ] showed that visual and vibrational ( lateral line detected ) stimuli elicit spawning behaviour in male red salmon oncorhynchus nerka .

our study revealed three different agonistic sound types ( two in males , one in females ) based on physical characteristics of sounds . mean sound duration in m . thoracata differed between sexes , with female crackles ( 167 ms ) being shorter than both male barks ( 219 ms ) and thumps ( 240 ms ) . mean spls of thumps ( 123 db ) were higher than those of barks ( 112 db ) and crackles ( 115 db ) . mean dominant frequency of female crackles ( 562 hz ) was much higher than that of male sounds ( 132–403 hz ) . in contrast , mayr [ 27 ] wrote that aggressive signals ( = thumps ) were shorter than territorial sounds ( = barks ) . nonetheless , there is a lack of information about whether male sounds differ from female sounds because the sound characteristics have not been compared statistically between sexes . differences between the current and the prior study by mayr [ 27 ] may reflect that the present study investigated subadult fish and the former only adult reproductive fish . our fish were most likely immature because we observed no reproductive behaviour in community tanks .

) . all show best sensitivity between 0 . 3 and 1 khz and a step decrease in sensitivity above 1 khz [

] showed that smaller swimbladders and fewer weberian ossicles results in a decrease in sensitivity above 1 kilohertz .

aep - audiograms of all representatives of the family callichthyidae investigated in the recent and in prior studies .

megalechis thoracata ( current study , females and males pooled ) , corydoras paleatus [ 33 ] , corydoras sodalis and dianema urostriatum [ 52 ] .

in summary , this is the first investigation showing sex - specific differences in agonistic behaviour , sound production , sound characteristics and hearing abilities using same - sex agonistic contests . the data reveal clear differences in agonistic behaviour , which have not been shown in any fish species before . this study furthermore indicates that differences in sound characteristics between sexes seem to be due to the dimorphism in the pectoral sonic organs in megalechis .

we want to thank tanja schulz - mirbach , walter lechner , jessica jaxion - harm , angelika zebedin , isabelle maiditsch and jasmin oswald for their help with sound level measurements , isabelle maiditsch for her advice regarding analysis of female sounds and hearing measurements , and sonja windhager for her introduction to camstudio . finally , we want to thanks michael stachowitsch for scientific english proofreading and a reviewer for its helpful comments .

this article was supported by the open access publishing fund of the university of vienna . the funders had no role in study design , data collection and analysis , decision to publish , or preparation of the manuscript .

data will be uploaded in our university’s repository as soon as the paper has been accepted .

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