Wintering Reddish Egret (Egretta Rufescens) Foraging Response To Environmental Variability On The Southern Texas Gulf Coast
Finer, Robert T.
The Reddish Egret (Egretta rufescens) is a rare species of heron due to its limited geographic range as well as its narrow habitat requirement, relying exclusively on coastal tidal flats throughout its yearly cycle. It is therefore vulnerable to stressors ranging from human coastal development to sea level rise due to climate change. While Reddish Egret breeding ecology has been well studied, little information is known about the wintering ecology of the species. With the goal of gaining more knowledge of its winter foraging habitat requirements, I conducted line transect surveys via boat of foraging Reddish Egrets from November 2019 to March 2021 in the Laguna Madre land cut of the Gulf Intracoastal Waterway, an area with a large portion of tidal flat habitat. Using negative binomial and logistic generalized linear mixed effect models of my count data and multiple environmental variables, I found increasing wind speed and an easterly wind direction had negative effect on the presence of foraging Reddish Egrets in the study area, while a westerly wind direction had a positive effect, suggesting that wind patterns influence the distribution of foraging individuals on the Texas coast. In comparison of light and dark plumage morph Reddish Egrets, higher air temperature and an increasing cloud cover was associated with a higher proportion of light morph to dark morph Reddish Egrets in the flats, indicating support for difference in foraging response between the two color morphs. This study will help in furthering knowledge of Reddish Egret winter foraging preferences and may help inform conservation actions including suitable habitat identification and protection in the future.
waterbird, reddish, egret, foraging, winter
Finer, R. T. (2023). Wintering Reddish egret (Egretta Rufescens) foraging response to environmental variability on the southern Texas Gulf Coast (Unpublished thesis). Texas State University, San Marcos, Texas.