| Concern over the recent decline of many neotropical migrant songbird species has led to an inquiry into forestry practices and the potential role that they play in this decline (Duguay et al. 2001). In southern Ontario, uneven-aged management is prevalent and is a preferable silvicultural practice due to the retention of higher canopy cover and emulation of natural disturbances by removing individual trees throughout the stand (OMNR 2000, Leupin et al. 2004). The Rose-breasted Grosbeak (Pheucticus ludovicianus) is a neotropical migrant songbird that breeds in eastern and central North America and its population has been undergoing a significant decline (Sauer et al. 2004). Rose-breasted Grosbeaks were studied in woodlots in southern Ontario from 2000--2004. Study sites included reference sites (uncut for on average 33 years) and recently cut sites undergoing two forms of silviculture. Uneven-aged silvicultural practices increased Rose-breasted Grosbeak density, nest site availability, and the abundance of wild fruits. Logging practices elicited minor decreases in insect biomass and abundance and increases in rates of parasitism by Brown-headed Cowbirds (Molothrus ater) in sites harvested below provincial standards (20 m2/ha). There were no significant effects on daily nest survival rates, clutch sizes, the number of fledglings, seasonal productivity or the age structure of Rose-breasted Grosbeaks. Rose-breasted Grosbeak populations appear resilient to the effects of uneven-aged forestry management practices in these deciduous woodlands. |
