Successful Adaptation

Abstract

Last fall some twenty people considered themselves godparents to a clutch of pied-billed grebes hatching a few feet from their front yards. Though fairly common in the Puget Sound area in summer, pied-billed grebes are among the best hiders and the shyest of birds, nesting in concealed areas of undisturbed marsh, lying so low in the water that from a distance their heads look like waves. Even the striking contrast of a black band on their whitish bills blends smoothly with the surrounding reeds and water. As more and more wetlands are being disturbed and built on, the birds must leave their customary breeding grounds or adapt to new situations.

The pair in this story decided to adapt. The male grebe spent all spring whooping and crying in the highly populated Yarrow Bay area of Lake Washington, not far from the shrinking marsh where grebes had nested for many years. Finally he attracted a mate in early August and they found a minimarsh. In a small inlet flanked by a condominium building with a boat marina and some single-family homes only a few yards from the water, grew a patch of lily pads. A board was trapped in the patch and on this the grebes built their nest. Water depth was measured at about forty inches. For five days the grebes worked, bringing in pieces of vegetation which made a comfortable, partially submerged platform of rotting greenery.

The first three eggs came quickly.

Then, as if the birds stopped to think about their family size, there was a week's wait before another egg arrived, followed by one more three days later. Five is a typical clutch size. The birds took turns sitting on the eggs. Though in full view of any watcher, the birds retained their stealth habits, such as diving when still at a distance from the nest, swimming under the weeds, and not popping up until right next to the nest.

By this time, word of the grebes was out among all the condominium dwellers and neighboring homeowners. The people did not exactly schedule sentry duty for themselves but it seemed as if at any given time of day and half the night, somebody was watching the birds. So it was that when a young man trying to dock his boat without power found it drifting toward the grebes, he soon had fifteen people yelling at him to "watch out, be careful, get that boat away from the birds!" Not knowing how else to cope, he jumped into the water and pushed his boat to the dock.

Throughout the incident, the birds were not alarmed. Grown used to boats coming and going, the grebes ignored them all. When a motor started, the birds might glance at the boat, then away. The birdwatchers' main worry was that the nest would break loose in a wind storm or a predator, such as a raccoon, would find it.

Nest and eggs stayed put and four babies hatched on the twenty-ninth day, September 10, with the fifth emerging September 13. The chicks were by no means as well camouflaged as their parents. Brightly striped as zebras in black and white, they also had disproportionately large red heads. Perhaps such markings help them hide in a reed bed but here they stood out clearly.

 

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