CAROLINA WREN SINGING PHENOLOGY AND EFFECTS OF TERRITORY INTRUSION ON BEHAVIOR
Date
2024-05
Authors
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Publisher
University of Delaware
Abstract
Carolina Wrens (Thyrothorus luddovicianus) are a common, territorial, and
non-migratory species with a large song and call repertoire. Despite this, few studies
have examined the use of Carolina Wren song in territorial displays, the vocal activity
of Carolina Wrens through multiple seasons, or whether urbanization affects vocal
rates. Autonomous recording units (ARUs) were deployed in 20 wren territories
(Newark, DE; White Clay Creek Preserve) and collected four hours of wren vocal
activity a day from March 2023 – February 2024 to establish the phenology of
Carolina Wren vocal behavior, and whether that behavior differs between urban and
forested habitats. This study aimed to 1) determine the relationship between male wren
territoriality and song by performing playback trials at known Carolina Wren
territories, 2) describe wren singing phenology over the annual cycle in urban and
forest sites, and 3) compare differences in vocalization rates of wrens in forested
habitats with wrens in urban habitats across the annual cycle. I conducted 63 playback
trials and found that focal wrens sang on average 2.21 additional male primary songs
after a playback broadcast. Wrens approached the trial area after the playback
broadcast but did not approach the area in response to a decoy wren. Using ARU
sound files (*.wav) and Kaleidoscope Pro, I did not detect a prolonged increase in
wren song rates after the immediate response to the playbacks. I used BirdNET to
identify wren vocalizations in 3-seconds windows of the 1,400 hours of recordings
each ARU collected during the year. Wren singing phenology varied during the annual
cycle and differed between urban and forested sites. I found that wrens vocalized more
in the four breeding season months (April–July) than the rest of the year and more in
urban territories than forested territories. In conclusion, I found that: 1) Carolina
Wrens increased song rate when they perceived conspecific intruders, 2) wrens
increased vocal activity during the breeding season, and 3) wrens vocalized more in
urban areas, likely due to anthropogenic noise.