A male cardinal (Cardinalis cardinalis) fluffs up to buffer the cold during the early winter in Texas. No matter what the time of year, the chirps and shuffles of cardinals are everpresent.
Like many red-orange colored animals, male cardinals (Cardinalis cardinalis) acquire their brilliant red coloration from carotenoid uptake in the diet. Carotenoid-based colorations have long been implicated in body condition and sexual selection, and the cardinal is no exception— several studies suggest plumage and bill redness are predictors of reproductive success and that cardinals mate assortatively. Beyond the eye-catching explosion of red, cardinals’ black face masks are easily overshadowed. It’s possible that melanin deposition is influenced by testosterone level, which may explain why mask area and brightness are associated with the level of intrasexual aggression (though evidence for this hypothesis is equivocal). In a study examining female ornamentation, face mask expression indicated level of parental care, which if true, may generate a selective pressure for male preference of female masks. Alternatively, face masks may simply serve as a contrast region to the red plumage to enhance the conspicuousness of the signal, though this remains to be tested.
Both photographed in situ