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THE FOOD AND GROWTH OF NESTLING WOOD‐PIGEONS IN RELATION TO THE BREEDING SEASON
Author(s) -
MURTON R. K.,
ISAACSON A. J.,
WESTWOOD N. J.
Publication year - 1963
Publication title -
proceedings of the zoological society of london
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.915
H-Index - 96
eISSN - 1469-7998
pISSN - 0370-2774
DOI - 10.1111/j.1469-7998.1963.tb01624.x
Subject(s) - biology , crop , nest (protein structural motif) , predation , feather , avian clutch size , seasonal breeder , zoology , agronomy , ecology , reproduction , biochemistry
Analysis of the food items stored in the crops of nestling wood‐pigeons, which were collected during the period July to October 1957, showed that their diet consisted mainly of cereal grains, with legume or mustard seeds of local importance. Weed seeds and leaves and some animal material comprised only a small proportion of the food. Nestlings collected in May in Cambridgeshire had been fed primarily on weed seeds suoh as Cerastium and Ranunculus species but increasing proportions of cereal grains were noted towards July. In early July unripe grain was collected. The mean daily weight of nestlings hatched in late June was below that of others examined in August and September. Similarly feather growth was retarded and many of these early nestlings died in the nest, apparently due to malnutrition. For the first three days of life the squabs were fed on crop milk but after this time environmental foods became increasingly important. Broods of one grew more quickly than broods of two and the absence of any clutch size adaptation to the food supply is discussed. In a study area near Newmarket the breeding season coincided with a peak in the availability of grain. The factors controlling this timing are discussed and food is considered to be the most important “ultimate” and “proximate” factor (Baker, 1938) concerned. A low nestling survival was recorded for those broods reared outside the period when optimum feeding conditions existed. Thus natural selection could eliminate early or late breeders. The condition of the gonads suggested that the pigeons were capable of breeding long before they did so. Egg laying was only partly synchronous throughout the population and occurred when the food supply was improving. It is considered that the food supply, by affecting the timing and duration of intra‐pair courtship and hence ovulation, could have been the main proximate factor regulating the onset of egg laying.