The drab ducks of August
The couple peered out over the marsh of Upper Klamath Lake with their spotting scope scanning the hundreds of ducks.
The marsh is beautiful in August. The sun is bright, and breezes ripple through the rushes that extend far out into the lake inviting canoe and kayak. Best of all, the mosquitoes have relinquished their reign over the marsh.
It would seem an excellent time to go birding. It’s true there are ibis and graceful terns, and myriad ducks dot the open water. But the ducks? They are all a frustrating brown. Even male wood ducks turn multiple shades of drab in August. The couple, while enjoying their outing, struggled to put names to the swimmers.
If they returned in October, and I hope they do, they would have little problem picking out the many species. Most of the ducks will have transformed into their distinctive breeding plumage. I’ll bet many of you could identify the males from a single feature. Let’s try. The first male has a bright yellow bill. The second has a white stripe running from the bill over the top of the head. The third has a bright brick-red body.
They are, in turn, a mallard, American wigeon and cinnamon teal. The question here is not why August ducks are all brown, but why are the males in breeding plumage so outlandish. It starts with the breeding system. Puddle ducks, those that do not dive for food, pair up in the winter. As soon as the clutch is complete in spring, the males split. They do not share in the incubating duties. They do not help care for the young once they hatch. The young never see dad.
When it comes time for these young to seek mates, this presents a problem. The males were raised by mom. They followed her everywhere she went, seldom straying more than a few feet from her for two months or more. Through experience, males have a very good image of the subtle characters that define females of the species. In contrast, the young females have never seen dad, and the marsh has many species to chose from. I suspect there is something in their DNA that allows them to recognize the bright yellow bill or brick red body as belonging to an appropriate potential mate.
In many other parts of the world, there are fewer breeding duck species to present confusion to young females. With few or no other species to present potential confusion, the males are as cryptic as the females. Bright colors come with a cost in nature. Predators often focus on the colorful.
In these less diverse areas, names offer the first clue that bright colors are abandoned when possible. There are brown teal, grey teal and grey ducks in New Zealand and Australia. That pretty well describes the plumage of the breeding males. The male koloa (a duck) of Hawaii is as brown as the female. The same is true for the mottled duck of the Gulf of Mexico coast. While many ducks winter in the southern United States, the mottled duck is one of the few that remains to breed.
So, here is another reason to praise biodiversity. If you want to enjoy our beautiful male ducks, you may have to venture to the marshes in the colder parts of the year. Bundle up.
Stewart Janes is a biology professor at Southern Oregon University. He can be reached at firstname.lastname@example.org.