Nature often surprises us, much to our delight. In a research project, a biologist follows a standard set of steps: observing a pattern in nature, devising a hypothesis to explain that pattern, and then devising experiments to try to disprove the hypothesis. During this research, a biologist will often uncover unexpected behavior and effects. The unexpected result I will describe today is amazing.

The bird of interest is the American woodcock, known widely across the state to non-birders as a timberdoodle. Woodcocks belong to the shorebird family, but with their dark mottled plumage and short legs, they are not typical shorebirds. They are forest birds, probing the soil with their long bill in search of their favored prey, earthworms.

Woodcocks have their eyes set well back on the sides of the head. Except for a narrow sector right behind the head, a woodcock can see almost all around itself without moving its head. Most images, though, are formed by one eye, so woodcocks do not have binocular vision like we do with our forward-facing eyes. In other words, woodcocks are not able to gauge distances very well. But once a potential predator is detected, the woodcock stands stock-still, and its dark plumage blends with the forest floor. A few black stripes on the head break up the outline of the bird so it is superbly camouflaged.

American woodcocks have an unusual mating system. About 95% of all species of birds have a monogamous mating system. A male and a female will develop a pair bond and raise one or more clutches of eggs together.

Some birds, like swans, common loons and bald eagles, mate for life with permanent pair bonds. Others, like ducks, change partners every year but maintain a single pair bond each year. Some species with multiple clutches in a season, like the eastern phoebe, may change partners with every clutch.

Another type of mating systems involving pair bonds is polygyny, where a male maintains pair bonds with multiple females. The red-winged blackbird is a good example.

The tables are turned in polyandry, where a female has multiple pair bonds with males. Even rarer are polygamous systems, where both males and females have multiple partners in the same breeding season. Woodcocks fit into a fifth category. They don’t believe in pair bonds. A male tries to attract females. If successful, the male mates with the female, and his contribution to any offspring is done. He is back on site trying to attract another female. This type of breeding is called promiscuity. The ruffed grouse is another local example. Males drum by rapidly flapping their wings from a stump to woo females.

The mating behavior of timberdoodles is well known. Most displays occur shortly before dawn and shortly after dusk.

A male will walk from the forest into a field or other cleared area and begin giving a distinctive peent sound. Then it explodes into the air, flying as high as 150 feet and slowly descending in circles, chirping the whole while. Air moving through their curved primary feathers causes a whirring noise. The male lands at its original spot. A female won by his behavior may approach, mate, and then leave him for good.

So, here is the remarkable new knowledge. A team of 28 researchers put satellite transmitters on more than 300 woodcocks to track their migration. Woodcocks overwinter in the southeastern United States and breed from the mid-Atlantic states into Canada as far west as Manitoba.

Of 200 tagged female woodcocks, over 80% nested along their migration route and then continued northward. Some females nested as many as six times during their migration. Because young woodcock can fend for themselves soon after hatching, a female can abandon her chicks and continue her migration.

We are used to thinking of birds in the spring migrating to the breeding grounds and then nesting. Woodcocks have muddied the water, nesting while migrating. This unexpected result would never have been elucidated without the help of the satellite transmitters.

Herb Wilson taught ornithology and other biology courses at Colby College. He welcomes reader comments and questions at whwilson@colby.edu

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