EFFECTS OF FOOD SUPPLEMENTATION ON THE TIMING OF NEST INITIATION IN BELTED KINGFISHERS

摘要: Numerous food supplementation experiments have tested the hypothesis that timing of reproduction in birds is limited by energy constraints. These studies generally concluded availability primary proximate factor affecting nesting birds. None these studies, however, has examined relationship between and piscivorous To determine whether was nest initiation Belted Kingfisher (Ceryle alcyon), we conducted a experiment from 1993 through 1995; additional descriptive data were collected 1992. Kingfishers nested early had heavier nestlings more likely to renest, event failure, than late-nesting This indicates reproductive advantage nesting. In 1994 1995, when began feeding treatment prebreeding season (8 March) provided enough fish meet estimated requirements pair kingfishers (90 g/d), nests supplemented initiated earlier those unsupplemented as predicted constraint model. 1993, later (20 April) less (20-30 there no difference dates nests. Although support prediction model, two patterns our not explained this First, few breeding relative an unmanipulated reference population. Second, sup- plemented outside range recorded unma- nipulated Based on patterns, argue variation arrival time females grounds, coupled with their selection territories based availability, offers feasible testable alternative habitat model predicts influences location re- production individuals, but does alter reproduction. A literature review revealed could distinguish models. We think it important consider before concluding results suggest future use spatial temporal controls partition into multiple causes (e.g., constraints, selection).