Abundance and occupancy of the western yellow-billed cuckoo (Coccyzus americanus) in Sonora, Mexico

Canadian Journal of Zoology, Ahead of Print. Unveiling factors that determine abundance and distribution of endangered wildlife species has important implications for their conservation across international boundaries. For instance, the Western Distinct Population (as defined by the U.S. Fish and Wildlife Service) of the yellow-billed cuckoo Coccyzus americanus (Linnaeus, 1758) has disappeared in most of the species ’ range across western United States and southwestern Canada but little is known about the conservation status at the southern edge of its breeding distribution in Mexico. To fill this information gap, we estimated abundance and occupancy rates of yellow-billed cuckoos using a standard broadcast c all survey protocol. We used Bayesian spatial count models to estimate cuckoo population density at survey sites. We used Bayesian hierarchical models to estimate the effects of geography, climate, and vegetation on occupancy rates while accounting for imperfect detection. Mean cuckoo count per tran sect for all sites was [math] = 9.00 ± 0.45 cuckoos. Overall cuckoo density was [math] = 13.18 cuckoos/km2 (SD([math]) = 5.61 cuckoos/km2). Overall cuckoo occupancy in Sonora was [math] = 0.538 (95% credible interval (ψ) = 0.488–0.600), but showed strong geographic variation. Relatively hi gh occupancy levels suggest yellow-billed cuckoo populations in Sonora may be robust, but they are largely reliant on declining high-tree cover.
Source: Canadian Journal of Zoology - Category: Zoology Authors: Source Type: research