Buffleheads (Bucephala albeola) are cute diving sea ducks that have a pronounced sexual dimorphism, especially in the breeding season. Here are the males vs. females from the Cornell bird site. This will help you pick out the sexes in the video below.
The video shows a group of bufflehead males trying to impress a few females. Note that the male display includes a lot of elements that demonstrate vigor, like head-bobbing, wing-flapping, and racing (in one case a female appears to incite a male to race). It’s hard to avoid thinking that females are looking for the most vigorous males, because those males have fewer parasites to transfer during mating (males have no parental care in this species), because the males have “good genes” that can be passed onto offspring, or a combination of these “direct” and “indirect” benefits.
But if female choice is basically random, as Richard Prum suggests, and has nothing to do with the genetic composition of the male, why are the most vigorous males always the ones who win? I suppose you cold say that they’re simply more conspicuous, but I don’t think so. These males are showing off a lot of different aspects of vigor, and the females are watching them closely before making their choice.
Anyway, enjoy the show!:
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