House Finch - Carpodacus mexicanus
The last birds that I made study specimens of at the prep lab were two male House finches. Dr. Willard had said that he likes having a broad range of male specimens in the collections to show the variation in plumage color. Since 1940 Carpodacus mexicanus has been rapidly spreading west from a small population that was released on Long Island, New York. They were originally native to just the western states, but they are now one of the most common backyard birds in urban and suburban environments throughout the US. Females are a dullish brown with heavy streaking, and while the males share similar markings on their body and wings, their faces and upper breast look to be stained with pomegranate juice. This stain of color can range from red, to orange, and less commonly (at least around here), yellow. Apparently the population introduced to Hawaii is made up largely of the yellow variety. Males obtain their color from carotenoid pigmentation in the food that they eat. And so, the variation in male coloration is due to variation in dietary access to carotenoid pigments. I always get a few of these at my thistle feeder, and they have very sweet vocalizations.