Posted by Mark Andrew Conboy
Any day now the skies over Eastern Ontario will begin to ring with the calls of Red-shouldered Hawks (Buteo lineaus). This vocal hawk is one of the most commonly encountered raptors on the Frontenac Arch. It’s also one of the few forest raptors that have been subject to long term monitoring in Eastern Ontario. Beginning in 1991 the Red-shouldered Hawk and Spring Woodpecker Survey has been conducted each year along Opinicon Road in an effort to keep track of Red-shouldered Hawk numbers. In this post I summarize the results of 20 years of counting Red-shouldered Hawks along Opinicon Road. The counts were completed by Ron Weir and others. Thanks to Ron for providing me with the survey data.
The results of the Red-shouldered Hawk surveys show that there has been a significant increase in Red-shouldered Hawk numbers since 1991 (P=0.0013). The lowest count was 5 birds in 1992. The highest count was 27 birds in 2003. The mean count is 17.05 birds. Red-shouldered Hawk numbers across their Ontario range appear to be steady or increasing and the data from Opinicon Road matches this trend.
QUBS is situated in what is currently the heart Red-shouldered Hawk abundance in the province (Cadman et al 2007). The largely intact forests that cover our part of the Frontenac Arch provide habitat for these sylvan raptors and are likely the reason for the high numbers recorded here. Red-shouldered Hawks may have been far more abundant than they are today all across Ontario prior to the conversion of forests to farmlands (Weir 2008). The species continued to decline in the mid 1900’s. In 1983 the Red-shouldered Hawk was designated a species of concern in Canada, due to the large declines in populations associated with forest clearing. In 2006 it was reclassified as not at risk. Today the most commonly observed hawk in the region is the Red-tailed Hawk (B. jamaicensis). It prefers large tracts of farmland or other open terrain. It has probably replaced the Red-shouldered Hawk throughout much of southern Ontario as a direct result of habitat alteration. However, at QUBS Red-shouldered Hawks remain more numerous than Red-tailed Hawks on most of our tracts.
- Cadman, M.D., Sutherland, D.A., Beck, G.G., Lepage, D. and Couturier, A.R. (editors). 2007. Atlas of the Breeding Birds of Ontario, 2001-2005. Bird Studies Canada, Environment Canada, Ontario Field Ornithologists, Ontario Ministry of Natural Resources and Ontario Nature.
- Weir, R.D. 2008. Birds of the Kingston Region 2nd edition, Quarry Press, Kingston.