South Carolina Project: Spatial Ecology of Brown Pelicans in the South Atlantic Bight

South Carolina Project

Spatial Ecology of Brown Pelicans in the South Atlantic Bight

September 2016 - December 2023

Personnel

Participating Agencies

USGS

As a nearshore marine predator and species of conservation concern, Brown Pelicans (Pelecanus oddicentalis) in the southeastern United States constitute a valuable study population for investigating coastal ecological systems. Despite occupying a highly visible and elevated trophic position in estuarine and oceanic ecosystems, movement parameters describing habitat use patterns, foraging behaviors, and migratory corridors are undeveloped at multiple spatial and temporal scales. This study aims to address these information gaps by outfitting breeding adult pelicans with high-resolution GPS satellite transmitters, which will provide accurate locational data throughout the annual life-history cycle. We will use these data to (1) examine movement and behavior of individual pelicans during the passage of hurricanes, (2) evaluate the risk exposure of pelican colonies to ship-based oil spills within Charleston Harbor, SC, using modeling products developed by NOAA, (3) assess the usage of discarded bycatch from shrimp trawlers by adult pelicans in relation to reproductive output by pairing movement data with diet samples, stable isotope analysis, and chick corticosterone concentrations, and (4) investigate the drivers of partial migration in brown pelicans and subsequently model shifts in both migration probability and non-breeding range of brown pelicans under multiple climate change scenarios.

Research Publications

Research Publications	Publication Date
Wilkinson, B.P., and P.G.R. Jodice. Support for the fasting endurance hypothesis of partial migration in Brown Pelicans. 2023. Ecosphere 2023;14:e4365. https://doi.org/10.1002/ecs2.4365 \| Abstract \| Download	February 2023	Partial migration occurs when only a certain fraction of a population or species migrates instead of all individuals. Considered an evolutionary precursor, understanding why some individuals choose to undertake migration while others do not may serve to inform general migratory theory. While several hypotheses currently exist for explaining the maintenance of partial migration, empirical support for many is limited. To address this gap, we analyzed telemetry data acquired from individual brown pelicans (<i>Pelecanus occidentalis</i>; <i>n</i> = 74), a partially migratory seabird, nesting on six colonies in the South Atlantic Bight over the course of four autumn migrations using a Cox’s proportional hazards model. We estimated that approximately 74% of pelicans nesting within the study area may be migratory on an annual basis, with the remainder staying within the surrounding marine ecoregion year-round. Mean date of migration initiation was 9 November, although movements occurred from September – December. Modeling results indicated significant effects of rising sea-surface temperatures and decreased body condition on migration rate. We suggest that the ontogenetic migration of the primary forage species of brown pelicans from estuarine to pelagic environments causes a seasonal reduction in prey, and that individuals in poor body condition are unable to meet the energetic demands potentially associated with this decrease in prey availability (i.e., the fasting endurance hypothesis of partial migration). Although we did not find evidence for a density-dependent migratory response, the effects of intraspecific competition on migration in pelicans appears to warrant consideration.
Wilkinson, B.P., and P.G.R. Jodice. 2022. Interannual colony exchange among breeding Eastern Brown Pelicans. J. Field Ornithology. 93(1) 5. https://doi.org/10.5751/JFO-00074-930105 \| Download	April 2022
Wilkinson, B.P., Y.G. Satge, J.S. Lamb, P.G.R. Jodice. 2019. Tropical cyclones alter short-term activity patterns of coastal seabird. Movement Ecology 7:30. https://doi.org/10.1186/s40462-019-0178-0 \| Download	November 2019
Wilkinson, B.P., A.R. Robuck, R. Lohmannm, H.M., Packard, P.G.R. Jodice. 2022. Urban proximity while breeding is not a predictor of perfluoroalkyl substance contamination in the eggs of brown pelicans. Science of the Total Environment 803 (2022) 150110 \| Download	September 2021

Presentations

Presentations	Presentation Date
Wilkinson, B.P., and Jodice, P.G.R. 2019. Expansion of Brown Pelican diet associated with shrimp trawling effort in South Carolina. 43rd Annual Conference of the Waterbird Society, Salisbury, Maryland.	November 2019

Theses and Dissertations

Theses and Dissertations	Publication Date
Wilkinson, B.P. 2021. Ecological outcomes of movement behavior in Brown Pelicans from the South Atlantic Bight. PhD Dissertation, Clemson University	December 2021

Cooperative Fish and Wildlife Research Units Program: South Carolina Education, Research and Technical Assistance for Managing Our Natural Resources