Hawk Cliff 2015 HawkWatch Summary

A few Hawk Cliff volunteers headed to the hawkwatch on August 21 to kick off the 2015 Hawk Cliff Hawkwatch season. Joined by many more in September, these volunteers eventually provided coverage until December 13, for a total of 117 count days, including 21 no-count days all of which were the result of inclement weather. In 2015, “inclement weather” usually meant rain, at times heavy, accompanied by strong southerly, (S, SW, SE) winds. Little snow was recorded during this hawk watch season, but observers did enjoy the unusually mild temperatures. Volunteers contributed a total of 518.25 hours, the highest number of hours’ coverage since the 2011 season. Again this year, our volunteers deserve a big thank-you for their dedication to the hawkwatch.

We’ve looked at the Birds per Hour (BPH) again for this summary which gives a truer feel for whether bird numbers were up or down compared to previous multi-year averages. This keeps the counts from being skewed by the assumption that the longer you spend on watch the more birds you see. This season we proved that assumption to be false. Compared to previous years, the 518.25 total hours for 2015 was only slightly below the past ten years’ average (539.20) so in terms of an average number of hours per day, we spent 4.47 hours per day for 117 days. Despite all those hours of observation, the total count in 2015 was only 53,559, far below the 15-year average of 67,246. Thus the total BPH was 103 for the season, much less than the 15-year average of 201 (2000-2014 inclusive).

The primary cause was the lack of a major Broadwing flight within range of observation from the hawkwatch. Our total for Broadwings was only 13,000 or only 10% of the highest count ever back in 2000 and well below the multi-year average of 33,400. Other species were also noticeably missing with our lowest ever count of Northern Goshawk (8) and nearly the lowest of Rough-legged (13). We did see our highest 1-day count ever though for Turkey Vultures (5,578) on Oct. 18, clearly a species that is not at risk in Ontario. All other species had lower BPH for 2015, many less than half the multi-year average. Let’s hope for bigger, better flights in 2016!