Grebes stand anywhere from 8.7 to 29.9 inches (22 to 76 centimeters) tall and weigh between 3.5 and 56 ounces (100 to 1,600 grams). The appearance and color in both sexes of these diving birds are similar, though the female is usually smaller. Their coloration varies, depending on whether or not they are breeding. Their wings are rather short and skinny. Their eyes may be yellow, red, or brown, and their bills are short. Because their feet have adapted, changed over time, to swimming, they are unable to walk well on land and can do so only for short distances.
Although their weight remains basically the same throughout their lives, their body mass distribution changes on a yearly cycle. When flight is needed, breast muscle is built up. When frequent diving is required, leg muscle is developed. And when flight feathers are shed each year, huge quantities of fat are deposited because grebes eat feathers. Eating these feathers gives their stomachs a protective lining against the many parasites that inhabit the grebes’ bodies. As many as thirty thousand parasites have been counted on one grebe.
Grebes live throughout the world but not in the Antarctic or high Arctic regions where temperatures are frigid.
Grebes live in freshwater ponds and lakes as well as slowmoving rivers. Northern populations migrate, travel from region to region seasonally, to inland lakes and coastal waters during winter months.
In addition to feathers, grebes eat many kinds of fish, including perch, herring, eels, minnow, pipefish, goby, and cod. They also eat water bugs, crayfish, shrimp, and snails.
Grebes are powerful divers and can feed just below the surface or in greater depths.
BEHAVIOR AND REPRODUCTION
Grebes like to sunbathe and preen, groom, themselves and spend a lot of time doing so. Many grebes have ten to twelve calls that they use, primarily during breeding season, while other grebes are almost completely silent year-round. Their vocalizations range from whistles to beeps to wails.
Grebes fly at night when moving between various regions. They sometimes fly in groups and loose flocks. The grebe is seasonally monogamous (muh-NAH-guh-mus), has only one mate each year. Nests are built by both parents on the water so that they float, but often they are attached to plant life. These birds build several other platforms besides the nest which they use for resting, mating, and sunbathing. Two to four eggs, or three to eight eggs at higher latitudes, are laid and incubated, warmed, by both parents for twenty-two to twenty-three days. After birth, both parents care for and feed the chicks, which take their first flights between six and twelve weeks of age. They are ready to breed at one year. Some species lay eggs two or three times each year.
Predators of the grebe, animals that hunt them for food, include weasels, mink, ferrets, crows, hawks, gulls, and pike. Grebes live to be anywhere from eleven to fifteen years old.
GREBES AND PEOPLE
Though once hunted for their plumage, feathers, and as food, grebes are considered bad-tasting in most parts of the world today. In China, the little grebe’s meat is used for medicine.
Although no species of grebe is immediately threatened, two species, the giant pied-billed grebe and Colombian grebe, became Extinct, died out, in the 1970s. The Alaotra grebe is listed as Vulnerable, facing a high risk of extinction in the wild. The numbers of the Madagascar grebe have declined recently to the point of concern, due primarily to habitat destruction and the introduction of exotic fish.