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Endangered Species Research

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ESR 28:123-134 (2015)  -  DOI:

Movements and survival of juvenile reddish egrets Egretta rufescens on the Gulf of Mexico coast

Brock Geary1,3,*, M. Clay Green1, Bart M. Ballard2

1Population and Conservation Biology Program, Department of Biology, Texas State University—San Marcos, San Marcos, TX 78666, USA
2Caesar Kleberg Wildlife Research Institute, Texas A&M University—Kingsville, Kingsville, TX 78363, USA
3Present address: Department of Ecology & Evolutionary Biology, Tulane University, 6823 Saint Charles Ave, 400 Lindy Boggs Center, New Orleans, LA 70118, USA
*Corresponding author:

ABSTRACT: Understanding natal dispersal patterns of animals is critical to development of effective species conservation plans, as it ensures that population management takes place at appropriate scales. The reddish egret Egretta rufescens is a threatened waterbird species lacking documentation on many aspects of its ecology, including movement behaviors at all life stages. We attached satellite transmitters to 25 juvenile reddish egrets on their natal colonies and observed their dispersal patterns and subsequent movements over a period of 115 wk (May 2010–August 2012). Birds exhibited the greatest movement rates in the remainder of the first breeding season (through July 2010, ~10 to 13 wk of age, 11.07 km d-1) and steadily decreased in the post-breeding period (4.87 km d-1) and winter (1.96 km d-1) of their first year. Movements of 1 to 2.5 km d-1 characterized the remainder of the tracking period, suggesting that surviving birds were able to establish local territories. Of the 25 tagged birds, 8 (32%) survived throughout the observation period, based on transmitter failure rates, with losses increasing each winter. The majority of birds remained on the Texas/Mexico coast of the Gulf of Mexico, indicating that the population is largely resident and therefore vulnerable to coastal habitat alterations in the region. Due to a combination of infrequent long-distance migration, specialized behaviors, and apparent limited gene flow, habitat maintenance should be of primary importance for management of this rare species. This is among the first published studies of heron movement ecology using telemetry, and should be followed by further tracking with developing technologies to characterize high-resolution movements and habitat associations.

KEY WORDS: Conservation · Dispersal · Gulf of Mexico · Movement · Reddish egret · Satellite tracking · Spatial distribution · Texas

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Cite this article as: Geary B, Green MC, Ballard BM (2015) Movements and survival of juvenile reddish egrets Egretta rufescens on the Gulf of Mexico coast. Endang Species Res 28:123-134.

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