Novel nest tree selection by a deciduous forest New World warbler

Abstract

The Cerulean Warbler (Setophaga cerulea), a Neotropical migrant passerine, inhabits deciduous forests across the eastern and midwestern United States and Canada. Within this broad geographic distribution, Cerulean Warbler populations select specific tree species for nest placement and are known to use a variety of deciduous tree species depending on the population. In southern Indiana, Cerulean Warblers typically nest in white oak (Quercus alba), but we have documented 19 tree species used, all of which are deciduous species. During 2018 and 2019, we discovered 2 instances of Cerulean Warblers nesting in pine trees (Pinaceae) in southern Indiana. Our observations suggest that Cerulean Warblers may in some instances select atypical nest sites as long as specific microhabitat characteristics are present at the nest location.