Setophaga ruticilla – American Redstart
A commonly-used tactic in avian courtship is sexual mimicry. This young male American Redstart looks almost exactly like the adult females but for a few scattered black feathers on his head. He’s old enough to breed at one year old, but inexperienced in finding food and defending a territory. By mimicking females, these young males can find breeding opportunities, perfect their songs, and seek out much-needed resources like food and shelter without aggression from the dominant adult males.
Piranga ludoviciana – Western Tanager
Each spring, many migratory songbirds grow in a showy coat of colorful feathers. This coloration, called alternate plumage, helps birds, usually adult males, attract a partner for the nesting season. It’s energetically expensive to grow new colorful feathers in and it makes them more conspicuous to predators, but such is the price of beauty in the avian world.
Ailuroedus crassirostris – Green Catbird
Australia’s Green Catbird is a resident of the rainforest understory. It couples its bright teardrop markings with a resonating call strongly reminiscent of a crying human baby in order to alert potential mates to its presence. Deep in the green darkness, being heard might be the only way to be found.
Centrocercus urophasianus – Greater Sage-grouse
While many birds use sound to attract mates, the Greater Sage Grouse provides a dramatic example of the use of acoustics. Males gather in leks and their complex series of booms, pops, and whistles produced in part by the males’ inflatable air sacs which are exposed during the dancing ritual. Females rely on these strange sounds to locate males across broad expanses of sagebrush and desert grasses, and judge them based on the quality of their acoustics.
Falco sparverius – American Kestrel
The skin color around the eyes and bill of American Kestrels is brighter in birds that are more successful hunters, since this coloration comes from molecules called carotenoids that are found in their prey. The richer the orange coloration, the more likely the kestrel is a skilled hunter that can provide food for nestlings. In biology, carotenoid-based skin and feather coloration is an example of an honest signal, for no amount of deceptive behavior can change their skin color.