Habitat Segregation Among Songbirds in Old-Growth Boreal Mixedwood Forest

Abstract

The foraging behaviour of ten species of insectivorous songbirds — Boreal Chickadee (Poecille hudsonicus), Golden-crowned Kinglet (Regulus satrapa), Ruby-crowned Kinglet (R. calendula), Blue-headed Vireo (Vireo solitarius), Tennessee (Vermivora peregrina), Blackburnian (Dendroica fusca), Magnolia (D. magnolia), Yellow-rumped [Myrtle] (D. coronata), Black-throated Green (D. virens), and Bay-breasted (D. castanea) warblers — was observed in the boreal mixedwood forest of Prince Albert National Park in central Saskatchewan. Birds segregated their habitat use by preferentially foraging in different tree species, and through preferential use of different foraging locations (height and position) within trees.
White Spruce (Picea glauca) was used more than expected by Yellow-rumped Warblers, and Golden-crowned and Ruby-crowned kinglets. Tennessee and Magnolia warblers used White Birch (Betula papyrifera), more than expected and Boreal Chickadees and Blue-headed Vireos used Balsam Fir (Abies balsamea) more than expected. Boreal Chickadees, Ruby-crowned Kinglets, and Tennessee, Blackburnian and Yellow-rumped warblers all used the bottom part of trees less than expected, while Blueheaded Vireos foraged near the top of trees less than expected. Large inner branches were avoided by Tennessee, Blackburnian and Yellow-rumped warblers, while Bay-breasted Warblers and Blue-headed Vireos avoided small outer twigs. In conifers, Blackburnian Warblers foraged significantly higher in the trees than all other species except Black-throated Green and Baybreasted warblers. Blackburnian Warblers also foraged significantly higher than Blue-headed Vireos and Magnolia Warblers in deciduous trees.