Bringing Up Baby
Scientists zero in on the caring and cunning ways of a seldom-seen waterbird
A red-necked grebe carries on its back a riotously patterned hatchling that appears both eager to explore this new world and reluctant to leave its downy throne. Because red-necks are especially elusive, darting underwater or hiding amid the greenery at water’s edge, we seldom get a close look at them, never mind see them in such regal repose.
But wildlife photographer Tom Ulrich has taken some 7,000 pictures of red-necked grebes over seven years at a lake in northwestern Montana. Among his more delightful images are those of an adult red-neck "back brooding"—carrying chicks on its back until they can swim on their own after a week or two. Many waterbirds are famed for their fidelity, and Ulrich says he’s seen the same pair return to the lake for several years, although biologists say they do not know how long red-necked grebe couples typically stay together.
As it happens, our appreciation of the birds’ parenting and survival skills is being deepened by biologists who recently discovered a behavior among red-necked grebes rarely observed in birds before—after-dark sojourns from the nest that may serve as a handy diversionary tactic.
One of seven grebe species in North America, red-necks acquire their distinctive neck plumage during late fall and also early spring, shortly before they mate and build nests along the edges of lakes, ponds and slow-moving streams and rivers ranging from Alaska to Wisconsin and Michigan. They winter in coastal waters from California to Alaska and from North Carolina to Newfoundland. One researcher estimates there are at least 45,000 red-necked grebes in North America. Some experts say the population is threatened by pesticides and vanishing habitats; others say the birds are so widely dispersed it isn’t known whether their overall numbers are going up or down.
A red-necked grebe is ungainly on land, often stumbling with legs set far back on its body. But it excels in the water. Its lobed feet—a feature that distinguishes it from ducks and loons—and agile legs provide lots of thrust and minimal drag. Streamlined and strong-boned, they’re proficient submariners. Red-necks, which eat everything from worms and shrimp to salamanders and fish, can plunge 30 feet below the water’s surface for a meal and can hold their breath for three minutes or more.
Preferring open water, where they are beyond the reach of predators such as raccoon and mink, red-necks move close to shore to breed. It’s a perilous trade off, affording the animals cattails, reeds and other vegetation for building a nest but also putting them and their eggs in harm’s way. In separate field studies, Bruce Eichhorst, of the University of Nebraska, and Gary Nuechterlein, of North DakotaStateUniversity, found that brooding red-necked grebes often abandoned their nests for hours at night, probably as a security measure. Eichhorst, working at the Agassiz National Wildlife Refuge in Minnesota, placed plastic eggs containing a sensor and transmitter in nests alongside real eggs; the nests stayed warm some of the night, indicating the parents were there, but then suddenly cooled off, presumably after the birds skipped out. Biologists had previously observed such absenteeism in only a few bird species and have assumed that it would chill the eggs disastrously. "A lot of people think bird embryos will die under these conditions, but these don’t," Eichhorst says.
Though the parents’ action may seem careless, the researchers speculate that the birds are evading nocturnal predators. It’s not clear whether the birds are just trying to save their own skin or protect their eggs by diverting attention from the nest—or both. Regardless, it’s a very unusual trick, says Nuechterlein, who has used temperature probes to monitor grebe nests in North Dakota. "This was surprising," he says. "After 20 years of studying grebes, I would have thought they were on their nest 95 percent of the time if not disturbed. Who knew?"
The studies widen our view of these birds, which evade enemies with apparent cunning. All indications are that red-necked grebes go to great lengths to care for their young. Once the eggs hatch, a family paddles for open water. The chicks ride on their parents’ backs, out of reach of predators such as pike and bass, with mother and father sharing the burden of bringing up babies.