THE FUNCTIONAL BASIS OF SOME BEHAVIOUR IN THE WOODPIGEONCOLUMBA PALUMBUS

Abstract

SUMMARYSome behaviour observed in a wild Woodpigeon population is described. During the winter, October‐February, the species is gregarious. Flocks roost and feed together but each bird maintains its own individual distance. On the feeding grounds intra‐specific competition is apparent, supplanting attacks and actual fighting occurring. Gregariousness is discussed, mainly in relation to the white wing‐ and neck‐markings, and is considered to serve the function of improving food exploitation.The development of territorial display from early spring to the main breeding season is described. Most birds were territorially active in mid‐July. There were many active males in May which appeared potentially capable of breeding, but which did not then breed. It is shown that the proportion of the day spent in territorial and other display increases towards the beginning of the main egg‐laying season. Territorial defence is undertaken by both sexes.The bowing display is the initial sexual advance of the male to the female. It contains display elements typical of the nest calling display and these in turn are related to nest building movements. The display is very suitable for appeasement and can arise during periods of aggressive conflict. Bowing displays are frequently given at a distance from the territory, especially on the feeding grounds.Nest calling is a submissive display, mainly shown by the male and is used to attract the female to the nest or potential nest site. Caressing can occur at the same time as nest calling or away from the nest, and possibly evolved from the food begging movements of the nestling. It usually precedes courtship feeding. On the physical level the display is used to stimulate ovulation in the female, so that when used for long periods in the absence of courtship feeding it appears as a ritualized display. Courtship feeding and copulation are discussed.The periods during the day when both sexes were present at the nest site were limited and occurred at around 07.00–9.00 and 15.00–17.00 hours (G.M.T.).During incubation the male attends the nest from about 10.00–17.00 hours (G.M.T.), the female sitting during the rest of the 24 hours. This gives the male nine hours and the female seven hours feeding time during the main breeding season. Although sufficient at such times it appears to be inadequate earlier in the year when the incubation routine is affected to the extent that nests are left unguarded. A higher predation rate on eggs results.When brooding small young the adults take turns as during egg incubation. Nestlings are fed at frequent intervals, usually when they beg for food, but the adults also initiate such behaviour. Later, when the squabs are no longer continuously brooded, they are visited by each adult only twice a day. The physiological adaptations of the method of feeding the young are discussed.The possible functions of the territory are reviewed and it is concluded that dispersal with consequent reduction in egg predation is the most important function served.The significance of the diurnal activity rhythms, which are a feature of all the breeding stages, is discussed. It is suggested that the food supply could act directly in determining the duration of sexual displays, which in turn could provide the final stimulus regulating the onset of breeding.