Response to foster nestlings by red winged blackbirds agelaius phoeniceus at different reproductive stages
Holcomb, L.C.
Wilson Bulletin 91(3): 434-440
1979
Accession: 006327903
Experiments were performed with red-winged blackbirds (A. phoeniceus) at different reproductive stages to determine the frequency of parental acceptance of nestlings. Nestlings aged 0-1, 2-5 and 6-9 days were placed in nests where the nest was complete without eggs and when the last, next to last, and 2nd to last eggs had been laid. Nestlings of these different groups were also placed in nests during normal and prolonged incubation. There appeared to be no great differences in ability of females to accept any age group of nestlings. However, during the egg-laying period most females fed nestlings sparingly and sometimes were aggressive toward nestlings. The frequency of acceptance of nestlings did not differ significantly between normal incubation and egg-laying periods and normal incubation and prolonged incubation periods (P > 0.05). The internal physiological mechanisms and the external stimuli that may account for the observed differences in behavior are discussed.