Migration ecology of American White Pelicans: circannual movement, geographic range, and annual survival

Responses of migratory birds to seasonal climate and long-term environmental changes have been a central theme of avian migration ecology. Atmospheric conditions (e.g., winds and thermals), climate, and land cover and land use (LCLU) are major factors influencing the flights of soaring birds. Soaring American White Pelicans (Pelecanus erythrorhynchos) (hereafter, AWPEs) migrate between the subtropical Gulf of Mexico (GOM) and the temperate Northern Great Plains. American White Pelicans are also economically important piscivorous birds, causing enormous damages to the commercial Channel Catfish (Ictalurus punctatus) aquaculture in the Southeastern US. My studies aimed to evaluate the effects of climate, wind, and LCLU on the geographic range distributions, seasonal movements, and annual survival of AWPEs. I used Bayesian integrated species distribution models to estimate the occupancy probability and space-use intensity of AWPEs at the breeding and non-breeding grounds in 2005, 2010, and 2015, respectively, with data from eBird, Breeding Bird Survey, and Christmas Bird Count. Decreases in wind speeds and surface net thermal radiation and increases in waterbodies, wetlands, and non-woody covers enhanced AWPE occupancy at both the breeding and non-breeding grounds. I used 72 GPS-tracked AWPE data to study circannual hourly movement speeds and seasonal home ranges of AWPEs from 2002 to 2012. American White Pelicans had shorter hourly movement distances and smaller seasonal home ranges in the Southern than Northern GOM during winters; however, the difference did not carry over to the shared breeding grounds during summers. Last, I built Bayesian integrated population models to estimate annual survival and population dynamics of AWPEs with mark-resight-recovery data and annual nest counts at Chase Lake, North Dakota, the US from 1960 to 2014. Increases in upward wind velocity during autumn migration enhanced hatch-year AWPE survival. Increased winter precipitation on the non-breeding grounds improved annual survival of yearling and adults. On the other hand, increased precipitation at the breeding grounds reduced annual survival of hatch-year AWPEs. My findings can help develop management plans for mitigating the economic damages of AWPEs by predicting what areas AWPEs may occupy with high abundances in the future changes in climate and LCLU