Bill size variation in northern cardinals associated with anthropogenic drivers across North America.

摘要: Allen's rule predicts that homeotherms inhabiting cooler climates will have smaller appendages, while those warmer larger appendages relative to body size. Birds' bills tend be at lower latitudes, but few studies tested whether modern climate change and urbanization affect bill Our study explored size in a wide-ranging bird would warmer, drier regions increase with rising temperatures. Furthermore, we predicted densely populated areas, due urban heat island effects the higher concentration of supplementary foods. Using measurements from 605 museum specimens, housing density on northern cardinal over an 85-year period across Linnaean subspecies' range. We quantified geographic relationships between surface area, density, minimum temperature using linear mixed effect models geographically weighted regression. then area changed three subregions (Chicago, IL., Washington, D.C., Ithaca, NY). Across North America, cardinals occupying had bills, pattern strongest males. This relationship was mediated by such birds warm, dry areas than cool, areas. Over time, female cardinals' increased warming temperatures Ithaca. Bill developed Chicago, there no NY. found were strongly associated for bird. These biogeographic characterized sex-specific differences, varying variability. It is likely anthropogenic pressures continue influence species, potentially promoting microevolutionary changes space time.