Survey techniques and habitat relationships of breeding birds in residential areas of Toronto, Canada

Abstract

We measured bird abundance and diversity in seven types of residential areas in Toronto, Canada, during the breeding season. We used transects and a combination of nest searching and spot-mapping. Transects underestimated the size for the breeding population for most species. Relationships between the two methods varied between species and residential areas indicating that for several species relative abundance was not directly proportional to breeding density. Several bird species responded similarly to habitat features. Rock Dove (Columbia livid), European Starling (Sturnus vulgaris) and Chimney Swift (Chaetura pelagica) were positively associated with house density and negatively with lawn area. House Sparrow was somewhat different, possibly because they built nests in conifers whenever cavities were absent thus they may not be so dependent on buildings. Another group, including Mourning Dove (Zenaida macroura), American Robin (Turdus migratorius), Common Grackle (Quiscalus quiscula) and Northern Cardinal (Cardinalis cardinalis), all were positively associated with low foliage and lawn area and negatively associated with house density. Other native species (Blue Jay [Cyanocitta cristata], Chipping Sparrow [Spizella passerina], Song Sparrow [Melospiza melodia] and Brown-headed Cowbird [Molothrus ater] shared the same habitat associations as the latter group to a greater or lesser extent. Conifers and shrubs appear to be the two key components linked to species diversity in temperate cities. Our results highlight the duality of the urban bird community structure: 1) the presence of typical urban birds (House Sparrow [Passer domesticus], European Starling, Rock Dove and Chimney Swift) that respond to architectural features first and to natural features second, and 2) the presence of native birds associated with remnant natural features, especially vegetation structure and volume.