Nestling Survival of White-faced Ibis in Lahontan Valley, Nevada, U.S.A

Abstract

Abstract This study examines the survival of first and second hatched White-faced Ibis (Plegadis chihi) nestlings from fledging until colony dispersal (age 8-42 days) in Lahontan Valley, Nevada, using the Kaplan-Meier method. Out of 81 radiomarked nestlings sampled from six colonies during a two-year period (1995 and 1997), 18 died before reaching the age of 42 days and eleven were excluded from consideration. No evidence was found to suggest that survival rates of first and second hatched nestlings were different within or among years. The overall nestling survival rate was 76% ± 0.05 SE. The primary mortality source was inclement weather exposure. Weekly conditional survival rates were highest during the first week (99% ± 0.01 SE), and lowest in the second (87% ± 0.04 SE) and fourth (93% ± 0.03 SE) weeks of life.