Factors influencing home range size and overlap in nonbreeding Kirtland’s Warblers on Eleuthera, The Bahamas

Knowledge of space use provides insight into a species’ habitat requirements needed for conservation. Little is known about space use of the near threatened Kirtland’s Warbler (Setophaga kirtlandii) wintering in The Bahamas, and how the warbler’s home range size and core area overlap among individuals and vary with sex and age, food availability, winter season, and habitat characteristics. To address these knowledge gaps, we used radio telemetry to determine sedentary home range size (95% adaptive kernel), core area (50% AK), and overlap for 27 radio-tagged warblers during two winters on Eleuthera, The Bahamas. Warblers monitored for ~3 weeks each had a median sedentary home range of 8.87 ha (range: 0.53–118.50 ha) and a median core area of 1.04 ha (range: 0.05–12.69 ha). Foliage of the warbler’s principal fruit species (Lantana involucrata, Erithalis fruticosa, Chiococca alba) was present in more warbler core area plots than in outlier plots (telemetry fix points outside the 95% AK home range) or in random plots within the landscape. Both size of home range and core areas increased with site disturbance age – consistent with declines in fruit abundance associated with age of vegetation. Warbler core areas displayed little pairwise overlap in two sites, “RS” and “MR,” examined during October–December (RS, x̄ = 1.49%; MR, x̄ = 0.55%) and at a site in January–February (MR, x̄ = 3.32%), indicating areas of exclusive use or territoriality. In contrast, a fruit-rich site (“OH”) in March–April had higher pairwise overlap in core areas (OH, x̄ = 8.56%), which may have resulted in competition for fruit. Our findings re-emphasize the importance of conservation at a landscape scale if spatiotemporal variation in food resources increases or become more concentrated prior to migration with extreme weather due to global climate change.

The post Factors influencing home range size and overlap in nonbreeding Kirtland’s Warblers on Eleuthera, The Bahamas first appeared on Avian Conservation and Ecology.