SUNGREBES: Heliornithidae

PHYSICAL CHARACTERISTICS

Sungrebes have long necks and slender bodies. They have brown backs and a long white stripe that extends down the side of the neck. Male and female sungrebes tend to have slightly different coloration on the heads and necks. The brightly colored bills of sungrebes are sharp and pointed, and the tail is long and broad. In one species, the African finfoot, the tail feathers are stiffened, and the tail is spread out on the water during swimming. All three species of sungrebes have brightly colored feet. These are orange in the African finfoot, green in the masked finfoot, and yellow with black stripes in the sungrebe.

GEOGRAPHIC RANGE

The African finfoot occurs in Africa, where it is found through most of sub-Saharan Africa. The sungrebe is a New World species found in parts of Mexico and through most of Central and South America. The masked finfoot is found in Asia, including portions of Bangladesh, India, Sumatra, and the Malay Peninsula.

HABITAT

All sungrebe species require overhanging trees or other forms of dense cover over aquatic bodies. They are found in swamps and other wetland habitats, as well as ponds, lakes, dams, and a wide variety of rivers and streams, from coastal creeks to mountain streams as high as 6,600 feet (2,000 meters) in elevation. Although sungrebes and finfoots are sometimes found in fast-flowing streams, most prefer slow-moving currents or still water. Some populations inhabit flooded rainforests.

DIET

Sungrebes feed primarily on insects, particularly midgets, mayflies, and dragonflies. They may also eat beetles, grasshoppers, and flies, as well as some mollusks, crustaceans, worms, millipedes, and spiders. Occasionally they can eat larger animals such as frogs, tadpoles, or small fish. Sungrebes are also known to eat a small amount of plant material, such as seeds and leaves. Most of their food is found on the water surface, but sungrebes also forage in overhanging vegetation or along banks.

BEHAVIOR AND REPRODUCTION

Sungrebes may be solitary, that is, may live by themselves, or are found in pairs, generally male and female breeding partners, or family groups. Sungrebes are permanently territorial, meaning they defend their territories from other individuals of the same species during the breeding season as well as the nonbreeding season. Sungrebes are shy birds rarely seen by people. They usually swim close to cover and may hide either in vegetation or in the water, with their bodies underwater and their heads lowered, when they are disturbed. They are good swimmers but also capable walkers and climbers. Sungrebes tend to roost, or spend the night, in trees or bushes.

Although all three subgrebe species have distinctive calls, these are not often heard. The African finfoot makes a loud booming sound during breeding. The masked finfoot has a bubbling call. The sungrebe has a "eeyoo" call that it makes to warn other sungrebes away from its territory.

RIDING UNDER THE WING

In monogamous birds, where each male mates with only one female during the breeding season, it is common for males to help with nest building, incubating the eggs, and caring for hatched chicks. Sungrebe males do one additional thing for their chicks—after the chicks hatch, the male carries one under each wing, secured in a pocket of skin. Males can even carry them while flying.

Sungrebes breed when water levels are high. All three species are monogamous (muh-NAH-guh-mus), meaning a single male breeds with a single female. Courtship rituals, which are characteristic behaviors individuals perform before mating, vary among the species. In the African finfoot, one individual raises and opens its wings while the other individual remains under cover and responds with a snapping noise. In sungrebes, potential mates swim in circles towards each other, raising their wings and lowering their heads in a characteristic manner. Both males and females participate in building the nest, which is generally a shallow bowl of sticks lined with dead leaves. Nests are generally built in areas of thick vegetation about 3 feet (1 meter) over water, often on top of debris that remains caught in branches. Usually, two to three eggs are laid at a time, and both parents incubate, or sit on, the eggs. Eggs hatch after ten to eleven days.

In the sungrebe, chicks are altricial (al-TRISH-uhl), that is, they hatch naked, without feathers, blind, and unable to move. Males carry the chicks in pockets of skin under the wings until they are better able to fend for themselves. In the African finfoot and the masked finfoot, the chicks are semi-precocial (semi-pree-KOH-shul), a state between altricial and precocial, fully developed. Although they cannot leave the nest immediately, as fully precocial chicks can, they generally leave the nest after a few days.

SUNGREBES AND PEOPLE

Masked finfoots are hunted for food. Their eggs and chicks may also be collected for food.

CONSERVATION STATUS

Masked finfoots are considered Vulnerable, facing a high risk of extinction in the wild. There are probably somewhere between 2,500 and 10,000 individuals left in the wild. Populations have suffered due to the loss of wetland habitats to agricultural or other human use, as well as hunting. The African finfoot is considered Vulnerable in South Africa, but may be in decline in other parts of its range as well. Because all three sungrebe species rarely come into contact with humans, population declines are often unlikely to be noticed.

SUNGREBE (Heliornis fulica): SPECIES ACCOUNT

Physical characteristics: Sungrebes are black on top of the head and on the back of the neck. The throat is white, the back is brown, and the belly is pale in color. The males has a dark upper bill, whereas the female's upper bill is red. The lower bill is pale in both sexes. Sungrebes have yellow and black striped feet. Sungrebes vary from 10.2 to 13 inches (26 to 33 centimeters) in length and 4.2 to 5.3 ounces (120 to 150 grams) in weight.

Geographic range: Sungrebes are found in the New World, from southeastern Mexico through most of Central America and South America as far as Bolivia and northeastern Argentina.

Habitat: Sungrebes occupy river, stream, pond, and lake habitats in forested areas, usually with dense, overhanging vegetation.

Diet: Sungrebes eat primarily aquatic insects. They catch their food on the water surface, or, less frequently, on land.

Behavior and reproduction: Sungrebes are territorial throughout the year, with males defending a length of shoreline usually about 590 feet (180 meters) long. In the northern part of its range, sungrebes breed in the spring. Elsewhere, they breed during the rainy season. Females lay two to three eggs which hatch after ten or eleven days. Both parents help incubate the eggs. The male carries the chicks in pouches under the wings.

Sungrebes and people: No significant interactions between humans and sungrebes are known.

Conservation status: The sungrebe is not considered threatened. However, due to the extreme shyness of the species, it is uncertain how populations are doing. ∎

FOR MORE INFORMATION

Books:

Ali, S., and S. D. Ripley. Handbook of the Birds of India and Pakistan. New York: Oxford University Press, 1983.

del Hoyo, J., A. Elliott, and J. Sargatal, eds. Handbook of the Birds of the World. Vol. 3, Hoatzin to Auks. Barcelona: Lynx Edicions, 1996.

Perrins, Christopher, ed. Firefly Encyclopedia of Birds. Buffalo, NY: Firefly Books, 2003.

Web sites:

"Family Heliornithidae (Finfoots)." Animal Diversity Web. http://animaldiversity.ummz.umich.edu/site/accounts/classification/Heliornithidae.html#Heliornithidae (accessed on April 28, 2004).

"Heliornithidae (Finfoots)." The Internet Bird Collection. http://www.hbw.com/ibc/phtml/familia.phtml?idFamilia=47 (accessed on April 28, 2004).

"Sun-Grebes, Finfoots." Bird Families of the World, Cornell University. http://www.es.cornell.edu/winkler/botw/heliornithidae.html (accessed on April 28, 2004).