No fly zone: These birds chill flightless most of the year
There’s a lot to be said for having a time of rest.
Trees drop their leaves and go dormant. Fungi retreat underground. Insects wrap in cocoons. Chipmunks hibernate. Lizards and turtles brumate — the reptilian version of hibernating. Humans developed a Sabbath and weekends.
Birds, however, are largely committed to being lightweight and active. Hibernation and weekends are not options for them.
Some smaller birds and nightjars can lower their metabolism to sleep through a cold night or even longer harsh conditions. Mostly birds survive tough weather by either migrating away or foraging voraciously.
Eared grebes, however, have found another way to amplify the benefits of rest. Out on our lakes and rivers, they are in their resting mode right now. As many birds do, they have toned down their social demands, dropping their extravagant yellow breeding plumage and the showy dances that go with them. They wear plain black and white now. They’re not singing, spending their time in loose solitude. Most surprising, they can’t even fly.
For nine to 10 months of the year, eared grebes don’t need to take wing. They need to feed: For themselves in winter, for their young in the spring.
So they give up flying for extended periods of the year. Their flight muscles shrink, and their digestive organs grow. They eat and they rest. The invertebrates of open water in places like Turtle Bay and along Park Marina in Shasta County become their meals and muscle. The water itself is their home and refuge. The birds don’t hibernate, but they eat and store their calories with high efficiency.
Spring will call soon. Then the eared grebes’ pectoral flight muscles will grow, and the winter’s rest and food storage will power their flights.
First they will wing their way to either Mono Lake on the east side of the Sierras or the Great Salt Lake in Utah. Those two lakes act as a staging ground for 99% of all the eared grebes in North America. They’re rich in brine shrimp on which the grebes feed; the more shrimp they swallow, the greater their reproductive success.
Well fed, the grebe flight muscles again develop, and they fan northward to nest in freshwater and saline lakes from northern California up through central Alberta and Saskatchewan. There they’ll court with elaborate dances on the water.
Well built for swimming, with their feet located back toward their tails, grebes are awkward — essentially crippled — on land. Following their successful aquatic dance courtships, they’ll build floating nests in cattails or similar vegetation. Depending in part on the density of brine shrimp in their staging ground lake, the grebes will raise one to eight chicks.
The chicks are quickly active, diving and hiding an hour after hatching. They also take warm rides on their parents’ backs.
Eared grebe parents will join with neighboring nesters to share parental duties.
As summer progresses, the young are increasingly on their own. By September they’ll have developed the strength to fly to one of the great saline lakes of the American West, where they can continue the cycle of losing their flight muscles, feeding and resting.
Go to www.wintuaudubon.org for local birding programs and a schedule of activities open to the public.