Friday, October 31, 2014

Back to Work for Drakes

male Hooded Merganser (c) John Ashley
Male Hooded Merganser displays: ritualized drinking (left) and crest raising (right)
It's late October, and our adult male Hooded Mergansers have all molted back into their handsome breeding plumage. These fancy feathers come out for a compelling reason - courtship has begun, even though nesting is still 6-7 months away.

Hooded Mergansers are seasonally monogamous. The pairs only stay together for one breeding season, and the bond dissolves when the females start incubating eggs. The males then molt into a drab, "basic" plumage and lay low for the rest of summer. About the time the juveniles are grown and the adult females are released from their motherhood duties, the adult males molt back into their fancy feathers and the whole thing starts again.

By late summer we start seeing antagonistic displays, as males grapple among themselves, and courtship displays where males vie to impress females. If he's successful, she pairs off with him and they spend the winter together before nesting next year.

The male Hoodeds do almost all of the courting while the females mostly just observe. There are a dozen or more ritualized, exaggerated movements, including: head shake, head pump, upward stretch, crest raising and crest depressed towards the female.

But my favorite courtship behavior is a serious head throw with croaking - as in frog sounds. The male starts with a crest raise, fanning his white head patch and pointing his black brow feathers forward into a point. With gusto, he whips his head back and releases a low-pitch croak that sounds exactly like a summer-time frog (listen here). Others have photographed this but, unfortunately, I've never been allowed. I've tried blinds and remote cameras, but the males always move away from the slightest shutter sound.

My second-favorite Hooded Merganser behavior is ritualized drinking. An excited bird dips its bill in the water and flings it skyward. Males perform this move with their crest depressed, and both sexes do this near each other as a pre-copulation behavior. Once pairs form, copulation can occur during fall and winter, before spring's longer days alter duck hormones to allow for fertilization and egg-laying.

Duck copulations in October are a part of pair bonding, and copulations through winter and spring are for pair maintenance. This usually involves two more behaviors. Females incite mating with a soft "gack" call while head bobbing, and steaming is the male's exaggerated swim away from her after mating.

What makes this all fun for me is to anthromorphize, watching the earnest ducks and comparing them to the odd behaviors seen in flocks of young humans who are still years away from raising a family. It's about the only way I can understand some exaggerated human behaviors.

male Hooded Merganser (c) John Ashley
Male Hooded Merganser performs a ritualized and exaggerated drinking motion