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Factors Influencing Bioacoustically Derived Arrival Timing of Three Migrant Bird Species in the Western Boreal Forest
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- Author / Creator
- Johnson, John, J
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Habitat alteration is the leading cause of bird population declines globally. Therefore, understanding the processes influencing habitat selection are important for the identification and protection of important areas for birds. Long-distance migrant birds are particularly vulnerable and are experiencing disproportionate declines relative to other avian groups. Preventing further declines requires a more thorough understanding of how quality habitat is assessed by birds and new measures for determining the potential productivity of a territory. Differences in territory settlement date (arrival) have been shown to reflect habitat quality on small spatial scales, thus differential arrival timing of migrant birds may help us address fundamental questions of habitat selection across landscapes. Despite widespread acceptance of arrival time as an indicator of habitat quality, a large-scale multi-species demonstration of this phenomenon is absent due the logistical difficulty of collecting the appropriate data. I investigated the potential value of habitat assessment through measured differences in relative migrant arrival date estimated from provincial scale long term bioacoustic monitoring. I first assess the descriptive ability of two different operational arrival definitions used previously to justify the arrival date of three boreal migrants (first detection and first instance of three-day consecutive detection) and an additional novel definition (the detection-gap definition). The descriptive ability of each was assessed through the strength of an assumed positive latitudinal relationship. I found that all definitions performed similarly, producing the anticipated latitudinal relationship in 8 of 9 species-arrival definition combinations. Therefore, I adopted the first detection definition to describe arrival in this system as it provides similar descriptive ability with reduced sampling effort. I then address large-scale settlement patterns of three migrants: Ovenbirds (Seiurus aurocapilla), Tennessee Warblers (Leiothlypis peregrina), and Yellow-rumped Warblers (Setophaga coronata) across the boreal regions of Alberta. I also examined the local settlement patterns of Ovenbird by comparing both relative arrival timing and measured density changes between nearby territories. Using predicted density as a habitat quality proxy, I found increasingly early arrivals in higher quality sites both provincially and locally for species where habitat specificity has been reported. I also found that sites where higher densities of Ovenbird are predicted to occur locally are filled to higher densities before sites of lower density. Finally, I found that additional life history characteristics including habitat associations and migration distance may be measurable through arrival timing comparison. In this study, I present the first landscape-scale examination of simultaneous multi-species migrant arrival time using bioacoustics. By correlating migrant arrival time and density, I demonstrate that density is a reasonable measure of habitat quality. Combined, density and arrival data provide a relatively low-cost way of assessing habitat quality and should be used to inform land management decisions in the boreal forest region.
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- Subjects / Keywords
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- Graduation date
- Fall 2021
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- Type of Item
- Thesis
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- Degree
- Master of Science
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- License
- This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.