Enregistrement de l'activité dans les conditions naturelles sur les pistes deFormica polyctena
Résumé1oOn donne une technique simple d'enregistrement de l'activité des fourrageuses deF. polyctena sur leurs pistes.2oL'activité dépend non seulement de la distance par rapport au nid, mais encore de la piste considérée.3oL'activité n'est nullement comparable d'une piste à l'autre; l'activité nocturne apparaît très souvent dans les pistes populeuses et peut manquer dans les moins populeuses.4oLes pistes différent donc non seulement quant à leur capacité d'apprentissage et leur agressivité (Chauvin, 1962, 1964), mais aussi quant à leur activité; le comportement est également différent suivant l'âge de la piste, tout au moins dans les pistes qui relient les fourmilières filles à la fourmilière mère.5oL'aller et le retour prédominent à des périodes du jour très irrégulières et qui diffèrent pour chaque piste.6oLa température mesurée près du sol n'a qu'une faible corrélation avec l'activité des fourmis.Summary1oA technique is described which permits an easy recording of forager ants activity ofFormica polyctena on their trails.2oAnts activity is regulated by the distance from the nest, but this regulation is not the same in all the trails.3oAnts activity is not the same in all the trails; nocturnal activity appears very often on roads upon which the rate of flow is very high and may lack entirely on neighbouring, less crowded, roads.4oThe ants on, the differend roads are very heterogeneous regarding not only their activity but also their agressivity, their learning facilities (Chauvin, 1963–1964); their behaviour differ also according to road age; i. e. time clapsed from the road foundation, at least in the trails between a mother-colony and a daughter-colony.5oOutgoing and ongoing are very irregular and don't occur at the same time in different roads.6oTemperature close to the ground shows only a weak correlation with and activity.
ON THE FORAGING ACTIVITY OF THE WOOD ANT
The movement of animals in search of food is one of the primary causes of their dispersion over the area which a population comes to occupy. As such its study, as well as being of considerable theoretical interest, has potentially some practical importance. For example, these movements probably determine the average age at which young plaice (Pleuronectes platessa) appear on the main fishing grounds for that species in the southern bight of the North Sea. It seems that their general offshore displacement from the so-called 'nursery grounds' off the Dutch coast can be regarded as analogous to random diffusion in physical systems, at least until the basic pattern is modified by the onset of sexual maturity and the consequent highly oriented spawning migration during successive winters. Some of the problems arising from local movements in fish populations have been discussed elsewhere (Beverton & Holt, in press), special attention being paid to the attainment of steady-state distributions in a strictly limited area within which the distribution of food organisms and refuges was not uniform.
Territory Among Wood Ants (Formica rufa L.) at Picket Hill
THE sketch-map (Text-fig. 1) shows the distribution in July, 1929, of the nests and trackways of the wood ants living in Dr T. G. Longstaff's bird sanctuary at Picket Hill on the edge of the New Forest near Ringwood, Hampshire. The ants were studied at irregular intervals between 1927 and 1929 during visits to Dr and Mrs Longstaff, to whom I owe a debt of thanks for hospitality, encouragement, and help in planning the survey. The wood ants lived only at one end of the garden, where a complex area of heather (Calluna vulgaris), birch (Betula alba), sallow (Salix caprea), oak (Quercus robur), and other plants, intersected by turfy paths and forming in places a dense undergrowth, has been kept for some years as a bird sanctuary (Longstaff, 1926). The ants were destroyed by the owner in 1930, owing to their repressive effect on the nesting birds. This can be seen in the sketchmap on which are marked the positions of the nests of willow wrens, whose nestlings are certainly liable to attack by ants (Longstaff, 1927), which have been observed elsewhere to keep away birds from pine trees (Hudson, 1923). The ants were named by Mr O. W. Richards, and the aphids by Mr F. Laing, to both of whom, and to Prof. E. B. Poulton, F.R.S., my thanks are due.