A comparison of eastern kingbird breeding biology in lakeshore and upland habitats

Abstract

We compared aspects of eastern kingbird (Tyrannus tyrannus) breeding biology between lakeshore and upland habitats in eastern Ontario. Nests were more closely spaced and eggs were laid earlier at the lakeshore than in the uplands. Within the lakeshore habitat, nests were more likely to be placed on small islands (< 0.2 ha) and eggs were laid earlier there than on large islands or the mainland shore. Kingbirds nesting in lakeshore habitat had some advantages: (i) moderated temperatures for nests placed low over water, (ii) more efficient foraging when feeding nestlings, and (iii) faster growing nestlings, relative to upland nestlings. However, upland nests fledged more young than lakeshore nests. Within lakeshore habitat, small island sites had the highest breeding success. With the exception of nest site location, which differed markedly between habitats, differences in breeding biology and behaviour between the two habitats were small. A lack of substrate specificity in foraging, together with an ability to use a range of nest sites, apparently allow kingbirds to nest successfully in a wide variety of habitats.