Tuesday, August 13, 2019: 4:20 PM
L016, Kentucky International Convention Center
Ryo Ogawa1, Guiming Wang2, Loren W. Burger3, Brian Davis4, Bronson K. Strickland1, D. Tommy King5 and Fred L. Cunningham5, (1)Department of Wildlife, Fisheries, and Aquaculture, Mississippi State University, Mississippi State, MS, (2)Department of Wildlife, Fisheries and Aquaculture, Mississippi State University, Mississippi State, MS, (3)Department of Wildlife, Fisheries & Aquaculture, Mississippi State University, Mississippi State, MS, (4)Wildlife, Fisheries, Aquaculture, Mississippi State University, Mississippi State, MS, (5)Mississippi Field Station, USDA/APHIS/WS. National Wildlife Research Center, Mississippi State, MS
Background/Question/Methods — Migratory birds manifest unique life history strategies compared to non-migratory birds. Facultative migrants skip migrations depending on endogenous and exogenous conditions. Consequently, facultative migrants may exhibit demographic variation in their annual life-cycle stages. However, how facultative migrants change their demographic traits under different climates on wintering and nesting grounds still remains unclear. American white pelicans (
Pelecanus erythrorhynchos) are facultative migrants during spring. We aimed to determine ecological mechanisms for variation in the age-specific survival and nest success of pelicans marked at Chase Lake, North Dakota. We used banding and live encounter data of pelicans from the USGS Bird Banding Laboratory and nest count data in Chase Lake from 1960 to 2014. We classified ages as hatch-year pelicans (0 to 1 year old), yearlings (1 to 2 years old), and adults (
>2 years old). We built Bayesian integrated population models by linking mark-resight-recovery models of banded pelicans with state space models of nest counts. We examined the effects of seasonal temperature and precipitation on the nest success and age-specific survival probabilities of pelicans. We tested relationships between adult pelican survival and nest success to examine the trade-offs of demographic traits.
Results/Conclusions — We found substantial variation in nest success of pelicans, intermediate variation in survival of hatch-year and yearling pelicans, and relatively stable survival of adult pelicans from 1960 to 2014. Increases in summer precipitation reduced survival of hatch-year pelicans. High water levels from heavy rains at Chase Lake may disturb pelican nest sites. The precipitation-induced disturbances could increase mortality of nestling pelicans before fledging. Cold temperatures in winter decreased survival of hatch-year and yearling pelicans. Hatch-year and yearling pelicans with small body size could be more susceptible to severe cold temperatures during winter than adult pelicans with large body size. Neither temperature nor precipitation influenced variability in adult survival or nest success probability of pelicans. However, survival of adult pelicans was inversely related to nest success probability. The inverse relationship of the demographic parameters may indicate the trade-offs of demographic traits between adult pelican survival and reproduction. We conclude that survival of hatch-year and yearling pelicans could be more susceptible to changes in climate than that of adults. Additionally, adult pelicans may exhibit trade-offs between survival and reproduction to optimize their life-time fitness.
