Observations of the Decline Over 47 Years, 1970-2016, in an Adirondack Breeding Population of Purple Finches Attributable to Climate Change.
Robert P. Yunick
Over a 47-year period, 1970-2016, a breeding population of Purple Finches (Haemorhous purpureus) was studied at an Adirondack mountain, New York state, location leading to the banding of 13, 256 finches and 3240 return captures in subsequent years of those birds (16,494 total captures, not including thousands of same-season repeat captures). Purple Finches were abundant breeders between 1970-1990, but declined abruptly from 1991-1995 through 2011-2015 by 52.1%. This decline coincides with a shift in the National Temperature Index anomaly going from negative to positive by +2.08 F during the Apr-Sep breeding season from 1971-1975 to 2011-2015. Average spring arrival dates were earlier by eight days from 16 Apr to 8 Apr and banding dates for newly fledged immatures were also earlier by eight days from 9 Jul to 1 Jul. Adult males (3309 banded, 51.9%) outnumbered adult females (3063 banded 48.1%) but included 814 brown-plumaged adults early in the season of unknown sex; 6017 hatching-year birds were banded. Returning adult males more greatly outnumbered adult females by 61.5% to 38.5%; while hatching-year birds that returned at a time when their sex could be determined were 58.9%male, 41.1% female. The oldest recaptured finches by their respective sexes were two males at 11 yr-01 mo and a female at 10 yr-0 mo.
Using Upper Mandible Lining Color to Age Black-capped Chickadees: Is it Reliable?
Megan A. Fylling, Trica M. Rodriguez, and Michael T.A. Krzywicki
Ageing birds in the hand is a challenging technical skill that requires experience, objectivity, and careful observation. For a variety of reasons, we occasionally find Black-capped Chickadees (Poecile atricapillus) difficult to age. Pyle (1997) suggests that the degree of color on the upper mandible lining may be a useful characteristic for ageing. We tested whether mouth lining color can be used in the absence of a reliable skull or other diagnostic age characteristic. Mandible lining color in adults tended to be darker on a 1-5 ranked color scale (mean = 2.64± 0.15, n=44) than juvenile birds (mean = 1.82 ± 0.08, n=141) and a Welch’s two-sample t-test resulted in a highly significant difference (p<0.001) between groups. However, variation within groups was very high. Therefore, we recommend that banders use mandible lining color strictly as a complementary confirmation of age and never as a primary characteristic for ageing Black-capped Chickadees.