Habitat associations and abundance of Eastern Black Rails (Laterallus jamaicensis jamaicensis) in southeastern Colorado

Hargett, Eleonora Murphy

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https://hdl.handle.net/2142/124383 Copy

Description

Title

Habitat associations and abundance of Eastern Black Rails (Laterallus jamaicensis jamaicensis) in southeastern Colorado

Author(s)

Hargett, Eleonora Murphy

Issue Date

2024-04-30

Director of Research (if dissertation) or Advisor (if thesis)

• Fournier, Auriel
• Benson, Thomas J

Committee Member(s)

• Rossi, Liza
• Matthews, Jeffrey

Department of Study

Natural Res & Env Sci

Discipline

Natural Res & Env Sciences

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Marsh birds
• Black Rails
• population estimation
• habitat
• species conservation
• Colorado

Abstract

The Eastern Black Rail (Laterallus jamaicensis jamaicensis), a federally threatened subspecies, is cryptic and difficult to study. Their elusive nature makes population monitoring challenging and for many years they have gone understudied. Once observed across the eastern United States, they currently occupy only a few interior regions and are largely limited to coastal marshes. Southeastern Colorado is one of the most prominent interior regions still occupied by Eastern Black Rails. Here, Eastern Black Rails are relatively common, but we have a limited understanding of Eastern Black Rail habitat needs and population status. We used broadcast surveys conducted in 2022 and 2023 to better understand habitat patterns associated with Eastern Black Rail presence. We found Eastern Black Rail presence is associated with areas of higher marsh coverage, tall and dense vegetation, and in dry years, moist soil. We found locations outside of the core occupied habitat had similar vegetative characteristics, but less marsh habitat as compared to the core occupied habitat. These results indicate Eastern Black Rails may be limited by marsh coverage instead of vegetative characteristics. We also used broadcast surveys conducted in 2019, 2020, 2022, and 2023 to estimate the abundance of Eastern Black Rails along the Arkansas River. We found detection increased later in the season and later at night but decreased with noise. We found occupancy increased with residual vegetation height and Virginia Rail (Rallus limicola) presence. We found abundance increased with live emergent vegetation height and marsh coverage but decreased with distance to a large marsh. We estimated 128–179 Eastern Black Rails at our surveyed locations along the Arkansas River. These results indicate southeastern Colorado is hosting a substantial portion of the larger Eastern Black Rail population and management actions in Colorado are necessary to avoid population declines that have been observed across the range. The results of this work will inform future monitoring efforts and will allow for an improved understanding of management priorities for Eastern Black Rails in southeastern Colorado.

Graduation Semester

2024-05

Type of Resource

Thesis

Copyright and License Information

Copyright 2024 Eleonora Hargett

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