[CT Birds] Chickadees and Titmice
ls.broker at cox.net
Tue Dec 17 17:25:25 EST 2013
From Steve Broker (Cheshire):
I've checked Connecticut CBC statewide data on observed chickadees and titmice for the past 30 years (1983-84 through 2012-13), with the following results:
Total # Black-capped Chickadees = 347,963 (Average = 11,599/year)
Total # Tufted Titmice = 148,084 (Average = 4,936/year)
Average # Black-capped Chickadee in 5-year intervals:
1983-84 through 1987-88: 12,949
1988-89 through 1992-93: 13,375
1993-94 through 1997-98: 13,661
1998-99 through 2002-03: 10,628
2003-04 through 2007-08: 11,078
2008-09 through 2012-13: 7,901
Average # Tufted Titmice in 5-year intervals:
1983-84 through 1987-88: 3,601
1988-89 through 1992-93: 4,408
1993-94 through 1997-98: 5,525
1998-99 through 2002-03: 5,458
2003-04 through 2007-08: 5,862
2008-09 through 2012-13: 4,763
Note: these are raw numbers, not adjusted for total party hours. We've had nearly the same number of Christmas Bird Counts (18) taking place during these 30 years, except: The Napatree CBC has an 11-year history; Edwin Way Teale, Trail Wood has conducted 27 CBCs during this time period; Barkhamsted has had 29 CBCs.
The most recent 5-year interval for numbers of Black-capped Chickadee is 61% of the first 5-year interval. The first significant drop-off year was 2000-01, and in 10 of the last 11 years B-c Chickadee numbers have been well below the 30-year average.
The 5-year interval 2003-04 through 2007-08 for numbers of Tufted Titmice is 163% the first 5-year interval. Tufted Titmouse numbers first jumped above 5,000 in 1993-94, and they have remained so for all but 4 subsequent CBC years. Interestingly, Tufted Titmouse has seen an overall decline in numbers, on average, during the last 5 years.
I believe Connecticut Christmas Bird Count numbers for the last three decades support the view that Black-capped Chickadees have declined in early winter numbers during the last 10 years or so, while Tufted Titmouse numbers over the same 30-year time period have increased in corresponding magnitude, although with some indication of more recent leveling off or decline.
I hope to address this issue further in the 2013-2014 Connecticut Christmas Bird Count review article that will appear in an upcoming issue of The Connecticut Warbler.
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