 On the breeding grounds , the male corn crake 's advertising call is a loud , repetitive , grating krek krek normally delivered from a low perch with the bird 's head and neck almost vertical and its bill wide open . The call can be heard from 1 @.@ 5 km ( 0 @.@ 93 mi ) away , and serves to establish the breeding territory , attract females , and challenge intruding males . Slight differences in vocalisations mean that individual males can be distinguished by their calls . Early in the season , the call is given almost continuously at night , and often during the day , too . It may be repeated more than 20 @,@ 000 times a night , with a peak between midnight and 3 am . The call has evolved to make a singing male 's location clear , as this species hides in vegetation . The frequency of calling reduces after a few weeks but may intensify again near the end of the laying period before falling away towards the end of the breeding season . To attract males , mechanical imitations of their call can be produced by rubbing a piece of wood down a notched stick , or by flicking a credit card against a comb or zip @-@ fastener . The male also has a growling call , given with the bill shut and used during aggressive interactions . 
 On the breeding grounds , the male corn crake <a href='null_genetive' title='1'><mark>'s</mark></a>advertising call <a href='drop_aux' title='2'><mark>is</mark></a>a loud , repetitive , grating krek krek normally delivered from a low perch with the bird <a href='null_genetive' title='3'><mark>'s</mark></a>head and neck almost vertical and its bill wide open . The call can be heard from 1 @.@ 5 km ( 0 @.@ 93 mi ) away , and <a href='uninflect' title='4'><mark>serves</mark></a> to establish the breeding territory , attract females , and challenge intruding males . Slight differences in vocalisations mean that individual males can be distinguished by their calls . Early in the season , the call is given almost continuously at night , and often during the day , too . It may be repeated more than 20 @,@ 000 times a night , with a peak between midnight and 3 am . The call <a href='been_done' title='5'><mark>has</mark></a> evolved to make a singing male <a href='null_genetive' title='6'><mark>'s</mark></a>location clear , as this species <a href='uninflect' title='7'><mark>hides</mark></a> in vegetation . The frequency of calling reduces after a few weeks but may intensify again near the end of the laying period before falling away towards the end of the breeding season . To attract males , mechanical imitations of their call can be produced by rubbing a piece of wood down a notched stick , or by flicking a credit card against a comb or zip @-@ fastener . The male also <a href='got' title='8'><mark>has</mark></a> a growling call , given with the bill shut and used during aggressive interactions . 
On the breeding grounds , the male corn crake  advertising call a loud , repetitive , grating krek krek normally delivered from a low perch witt da bird  head and neck almost vertical and its bill wide open . Tdacall can be heard from 1 @.@ 5 km ( 0 @.@ 93 mi ) away , and serve to establish the breeding territory , attract females , and challenge intruding males . Slight differences in vocalisations mean dat individual males can be distinguished by their calls . Early in thdaeason , the call is given almost continuously at nite , and often during theday , too . It may b repeated more than 20 @,@ 000 times a night , with a peak between midnight and 3 am . The dal done evolved to make a singin male  location clear , as this species hide in vegetation . The fdauency of callin reduces after a few weeks but may intensify again near the endaf the laydaperiod before falling away towards the end dathe breedda season . To attract males , mechanical imitations of their call can bbproduced by rubbing a piece of wood down a notched stick , or by flicking a credit card against a comb or zip @-@ fastener . The male also got a growling call , given w/ the bill sda and used during aggressive interactions .