Diel variation in detection and vocalization rates of king (Rallus elegans) and clapper (Rallus crepitans) rails in intracoastal waterways

Waterbirds
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Abstract

Surveys for secretive marsh birds could be improved with refinements to address regional and species-specific variation in detection probabilities and optimal times of day to survey. Diel variation in relation to naïve occupancy, detection rates, and vocalization rates of King (Rallus elegans) and Clapper (R. crepitans) rails were studied in intracoastal waterways in Virginia, USA. Autonomous acoustic devices recorded vocalizations of King and Clapper rails at 75 locations for 48-hr periods within a marsh complex. Naïve King and Clapper rail occupancy did not vary hourly at either the marsh or the study area level. Combined King and Clapper rail detections and vocalizations varied across marshes, decreased as the sampling season progressed, and, for detections, was greatest during low rising tides (P < 0.01). Hourly variation in vocalization and detection rates did not show a pattern but occurred between 7.8% of pairwise comparisons for detections and 10.5% of pairwise comparisons for vocalizations (P < 0.01). Higher rates of detections and vocalizations occurred during the hours of 00:00–00:59, 05:00–05:59, 14:00–15:59, and lower rates during the hours of 07:00–09:59. Although statistically significant, because there were no patterns in these hourly differences, they may not be biologically relevant and are of little use to management. In fact, these findings demonstrate that surveys for King and Clapper rails in Virginia intracoastal waterways may be effectively conducted throughout the day.

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Publication type Article
Publication Subtype Journal Article
Title Diel variation in detection and vocalization rates of king (Rallus elegans) and clapper (Rallus crepitans) rails in intracoastal waterways
Series title Waterbirds
DOI 10.1675/063.040.0307
Volume 40
Issue 3
Year Published 2017
Language English
Publisher The Waterbird Society
Contributing office(s) Forest and Rangeland Ecosystem Science Center
Description 9 p.
First page 263
Last page 271
Country United States
State Virginia
Other Geospatial Pamunkey River
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