SONGBIRD HABITAT USE IN SASKATCHEWAN OLD-GROWTH, BOREAL MIXEDWOOD FOREST

Abstract

The purpose of this study was to determine how the songbird species composition of the boreal, mixedwood forest changed as it aged from middle­ aged (50- 60 years) to very old (over 130 years), and to determine the minimum age of forest needed to support all species in this community. The study also examined in detail how twelve species of similar, foliage-gleaning song birds could co-exist in the spruce-dominated, old-growth stage of this forest type. I found that there was a group of five songbird species that did not occur in forest under 100 years old, and reached their highest densities only in forest that was over 130 years old In addition, there were six other species that did not occur in forest under 80 years old and reached their highest densities in forest 100 or more years old. The twelve species of songbirds I studied used the available habitat differently from each other by foraging in different kinds of trees and at different heights within the same tree species. Four bird species were not observed foraging in deciduous trees, and three species did not use balsam fir-but all twelve species were observed foraging in white spruce. Vertical stratification between the bird species was best developed in white spruce because all the birds foraged in this tree and because spruce were tallest. From the results of this study,I conclude that the older age classes of boreal, mixedwood forest are an important part of the boreal ecosystem and play a key role in the survival of many forest songbirds. I also conclude that within the old-growth forest, white spruce is a very important tree species that is heavily used by foliage gleaning songbirds. It is important to ensure that all forest age classes continue to exist and that forestry practices do not truncate the normal successional sequence of the boreal, mixedwood forest.