THE PIED-BILLED GREBE: PART BIRD – PART SUBMARINE
By John Hughes
Often described as a floating chicken because of its blocky head and high, short bill, the Pied-billed Grebe, Podilymbus podiceps, is my favorite species of waterfowl. It is the first bird I seek out when visiting a wetlands, pond or marsh, and I’m disappointed if I leave without finding and observing one. Pied-bill refers to the two-colored bill during its alternate or breeding plumage, and the Latin genus for grebe means “feet at the buttocks.” Very fitting considering their feet are located at the rear of their body. My main objective in finding these guys is to observe them literally sink out of sight without the slightest effort. Squeezing air from between the body and feathers and expelling air from internal air sacs allow grebes to accomplish this change in buoyancy. Hiding birds can stay this way indefinitely with only their eyes and nostrils above water.
The Pied-billed Grebe is widely distributed throughout Montana and is usually easy to find if you know some identifying characteristics. It is a small, stocky grebe 30.5 to 38.1 cm in length and a mass of 253 to 568 g with the male larger and heavier billed than the female. The bill is laterally compressed with a decurved tip. Bill color varies depending on the season. During the breeding season, it is bluish-white with a prominent vertical dark bar on each side, and during the winter is flesh-colored and lacking the black vertical bar. Males and females have the same plumage coloration. Birds in breeding plumage have dark brown upper parts and grayish buff sides of the neck and flanks with a well-defined black throat patch outlined in white. The tail is relatively short with white under-tail coverts. Winter plumage is similar but the sides of the neck and flanks are reddish brown and the throat appears pale.
Pied-billed Grebes prefer wetlands with an even mixture of emergent vegetation and open water deep enough for foraging. They are opportunistic feeders taking a wide variety of food types including crustaceans (particularly crayfish), small fish, amphibians, aquatic insects (larva and adults) and other invertebrates. Foraging is typically done underwater though insects can be snapped from the air or captured from the surface of the water or emergent vegetation. As with other grebes, the rear positioned legs make them excellent swimmers but poor waders. Pied-billed Grebes do not have webbed feet like a duck but rather have lobed toes that help propel them through the water. Different toe lengths, like different primary flight feathers, along with adaptations in their legs allow these birds to turn on a dime while pursuing prey under water. Like other grebes, Pied-billed Grebes consume large quantities of their own feathers. They also feed feathers to their young. The feathers form a sieve-like plug that prevents hard, non-digestible prey parts from passing into the intestines and facilitates the production of pellets that are regurgitated.
These grebes are monogamous during the breeding season. Bonds are formed during migration or soon after arriving on breeding grounds. Males are very aggressive and set up and defend territories. Both sexes participate in building a floating nest attached to emergent vegetation. Nests are constructed of both living and decaying vegetation and mud. Some evidence suggests warmth from decaying vegetation helps with incubation of the eggs. An average of six eggs are laid in the nest and are brooded by both parents. Incubation lasts between 23 and 27 days. Upon hatching, the chicks stay close to the nest for the first week and will ride on their parents’ backs when venturing farther from the nest. The young have zebra-like striping that helps camouflage them. Both parents tend to the young, which begin to feed on their own in about 28 days. Chicks still beg for food after five weeks but are capable of feeding themselves.
Pied-billed Grebes are listed as a species of least concern due to their wide distribution and high population numbers. However, since they depend on healthy wetlands for their success, we should continue to work to protect these wetlands from degradation or destruction.
Migration in western Montana is dependent on whether or not there is open water. When migration occurs, it happens at night, which is one reason you will rarely see a Pied-billed Grebe in flight. They prefer to dive rather than fly if threatened. If you look for Pied-billed Grebes in the spring, you will probably hear them before you see them. During territorial defense, males give a loud distinctive call “cow-cow-cow-cow-cow-…cowp…cowp…cowp…” Other calls are produced, but this one is the most easily discerned and is a tip-off to start your search. A good place to look for Pied-billed Grebes is Dahl Lake at Lost Trails NWR. Just remember they might be hiding in plain site.