Date of Award

Spring 2021

Document Type

Thesis

Degree Name

Master of Science in Fisheries and Wildlife Science

Department

Biological Sciences

College

College of Natural & Health Sciences

Committee Chair

Dr. Christopher J. Kellner

Second Committee Member

Dr. Jorista Garrie

Third Committee Member

Dr. Thomas E. Nupp

Program Director

Dr. Thomas E. Nupp

Dean of Graduate College

Dr. Richard Schoephoerster

Abstract

Rusty Blackbirds are one of the most rapidly declining songbirds in North America. They have lost an estimated 85-95% of their population since the 1960s. Unfortunately, we currently do not know what is causing their decline. However, since habitat alteration and loss in their nonbreeding range has been much more severe than in their breeding range, many think the decline is associated with winter habitat loss. Consequently, knowledge of winter ecology, with a focus on habitat use and selection, may provide management insights useful for reversing the decline. My field assistants and I (hereafter we) used radio telemetry to collect data on the Rusty Blackbird’s home range, habitat use, behavior, and survival during the winters of 2018-2019, and 2019-2020. Radio-tagged birds were captured and monitored in agricultural and urban landscapes. We found that home ranges were larger in the agricultural landscape, and blackbirds selected for pecan groves and riparian zones, while cattle fields and rice fields were used much less. In the urban landscape, we found that home ranges were smaller and much patchier, and selected habitats included seasonally flooded hardwood forest, residential lawns, and urban parks. Cattle fields, non-residential areas, and agricultural areas were generally avoided in the urban landscape. Home range size may have been associated with habitat patch size and fragmentation; Home ranges were larger and less patchy in unfragmented homogeneous pecan groves than in heterogeneous urban habitats. The overall high survival suggests that these largely anthropogenic habitats may be effective substitutes for more traditional bottomland hardwood habitat –much of which has been lost to human activity. The Rusty Blackbirds’ use of these anthropogenic habitats presents unique opportunities and challenges in the management of this species. Urban landscapes, which are highly fragmented, can be managed at the patch level to provide a mosaic of suitable habitats in a matrix of urban development. Agricultural landscapes v can be managed at the habitat level to provide large, contiguous patches of habitat. Due to the Rusty Blackbirds’ use of privately-owned land, outreach and education will need to be included in conservation efforts.

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