Breeding biology and nesting behavior of the endemic subspecies of White-eyed Vireo ( Vireo griseus bermudianus ) on the Bermuda archipelago

Abstract

. Avian island endemics are prone to extinction, and the preservation of remaining taxa requires long-term studies of their natural history and threats to survival. Thus, we provide, for the first time, a detailed account of the breeding biology and nesting threats of an endemic subspecies of vireonid, the non-migratory Bermuda White-eyed Vireo ( Vireo griseus bermudianus ). From 2016– 2021, we located 84 nests, collected breeding data associated with 47 breeding pairs, and conducted observations throughout the nesting cycle. Some breeding pairs remained together for up to four successive breeding seasons. Bermuda Vireos began building nests in late February and cared for fledglings until mid-August. Both sexes contributed to all nesting stages, which were similar in duration to those of other vireo species ( N , mean ± standard deviation): nest building (13 nests, 6 ± 3 d), incubation (11 nests, 14 ± 2 d), nestling care (6 nests, 11 ± 2 d), and fledgling care (5 nests, 41 ± 12 d). Nests, eggs, and nestlings were all vireonine in structure and appearance; nests were found in 14 tree species (2 endemic, 2 native, and 10 introduced). Across six years, 25 of the 42 nests (60%) with eggs