Range expansion and the breakdown of Bergmann's Rule in Red-Bellied Woodpeckers (Melanerpes carolinus)

摘要: Abstract Previous studies of northward expansion breeding ranges North American bird species have focused on correlated changes in climate and land-use, but very few examined patterns morphological change within the context range expansion. We used data from museum specimens to examine geographic temporal variation body size Red-bellied Woodpecker (Melanerpes carolinus), a undergoing dramatic plotted georeferenced occurrence Christmas Bird Counts (winter distributions going back year 1900), USGS Breeding Surveys (summer since 1966), holdings twenty-six natural history museums (year-round 1867) document historic M. carolinus decade increments. Counts, not specimens, indicate trend slow beginning as early 1910s, all sets show rapid north west 1950s (average ...