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

Endangered Species Research

Bart M. Ballard¹  Brock Geary¹  M. Clay Green¹ 

关键词: Conservation;    Dispersal;    Gulf of Mexico;    Movement;    Reddish egret;    Satellite tracking;    Spatial distribution;    Texas;   

DOI  :  10.3354/esr00682

学科分类：动物科学

来源: Inter-Research

【 摘 要 】

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.

【 授权许可】

Unknown