Monday, February 29, 2016

Winter Bird Population Survey 2015-2016

The 24th year of RRBO's Winter Bird Population Survey has been completed.

After two brutally cold winters, this one was much milder, less snowy, and generally more pleasant. Surveys were conducted on 13 days (one day fewer than the mean) and a little over 20 hours total (lower than the mean of 28). Access restrictions continued this year. I was unable to survey anywhere along the Rouge River from Fair Lane Estate south due to it being fenced off for continued riverbank restoration. Thus, no Belted Kingfishers or Rock Pigeons were recorded (for the latter, the first time in 24 years). Only a few herons, and not many waterfowl were counted. Heavy construction activity continued along Fair Lane Drive for the new science building, impacting bird activity along eastern edge of survey area.
 
Nonetheless, the 38 species tallied was right on average. Two new species for the survey were recorded: Sandhill Crane and Wood Duck. These early migrants came at the very end of the season following a very warm weekend with southerly winds. These bring the cumulative total for the survey to 77 species.

Other uncommon species included a Bald Eagle; this adult bird was first seen in late December and continued to be spotted throughout the count period along the Rouge River (mostly on the south end of campus and along the concrete channel) but was only seen on one survey day. Although eagles are almost annual here, it was only the second time one has been recorded on this survey. A (singing!) Fox Sparrow early in the survey period was the third recorded for the survey. One or two American Crows were found on 4 survey dates. These birds were at the far north end of the campus.

At the other end of the spectrum, 7 species were found on all 13 survey days. In descending order of abundance they were: House Sparrow, House Finch, Northern Cardinal, Blue Jay, Black-capped Chickadee, Downy Woodpecker, and White-breasted Nuthatch -- all feeder birds. House Finches and House Sparrows were recorded in numbers well above average. For House Finches it was a record year, with a 127% increase from average.

Once again fruit-eating birds were largely absent. Three Cedar Waxwings on the first survey day were the only ones of the season. No Hermit Thrushes or Yellow-rumped Warblers were recorded. American Robins were counted, when present, in single digits most of the period. Last year robins were generally scarce on regional winter bird counts. This winter numbers of robins reported to eBird in southeast Michigan were much higher than last winter.  This suggests that the removal of fruit-bearing non-native trees and shrubs that is being undertaken by the university the past few years has had an impact on these numbers. This seems to be substantiated by data recorded this year showing that only 30% of the robins recorded were in areas where this type of vegetation removal had taken place.

For all the numbers from this year you can visit the RRBO web site. The page includes past counts and the history and methodology of the survey. 

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