MESITES AND ROATELOS: Mesitornithidae

PHYSICAL CHARACTERISTICS

The three species of mesites and roatelos are approximately 12 inches (30 centimeters) in length. Mesites and roatelos are characterized by short, rounded wings, long, wide tails, and sturdy legs. Their bills curve downward, making it easier for them to forage, or hunt for food, on the forest floor.

GEOGRAPHIC RANGE

Mesites and roatelos are found exclusively on the large island of Madagascar, off the eastern coast of Africa. The brown mesite (also known as the brown roatelo) occupies forested areas in the eastern part of the island. The white-breasted mesite (or white-breasted roatelo) is found in forests in the western and northern parts of the island. The subdesert mesite occupies a small area between the coast and hills in the southwestern potion of the island.

HABITAT

Mesites and roatelos are found in distinct habitats on Madagascar. The brown mesite inhabits humid rainforests. The white-breasted mesite inhabits deciduous (leafy) forests. The subdesert mesite occupies open, spiny thicket habitats.

DIET

The brown mesite and white-breasted mesite eat insects and other invertebrates, seeds, and small fruits from the leaf litter on the forest floor. The brown mesite and white-breasted mesite have bills that are adapted to lifting leaves without disturbing prey that may be hiding underneath. The subdesert mesite has a longer, more extensively curved bill that allows it to find invertebrates on the ground. Like the other mesite species, however, the subdesert mesite will sometimes feed in the leaf litter.

BEHAVIOR AND REPRODUCTION

Mesites are diurnal, that is, they are active during the day. Mesites spend most of their time on the ground. Although they are able to fly, they generally do so only when threatened. Mesites are social species, that is, individuals congregate with other members of the same species. In the brown mesite and the white-breasted mesite, birds can often be found in groups of three. This is frequently a male and female pair with their most recent young. The subdesert mesite is generally found in larger groups, of anywhere from six to ten individuals. Both white-breasted mesites and subdesert mesites are territorial, that is, they will defend their territory from other individuals of the same species.

Mesite songs can be fairly complex. In both brown mesites and white-breasted mesites, the male and female of a pair will sometimes sing together.

The brown mesite and white-breasted mesite are monogamous (muh-NAH-guh-mus), with each male bird mating with only a single female. The subdesert mesite is polygamous (puh-LIH-guh-mus), with each male mating with multiple females. Mesites build nests of sticks in low bushes. Usually the female lays one to three eggs at a time sometime during the rainy season from October to April. It is not known how long the eggs take to hatch. Mesite chicks are precocial (pree-KOH-shul), meaning that they are fairly well developed when they hatch. For example, they have feathers and are able to move around. Mesite chicks tend to stay with their parents for quite some time. In the case of the white-breasted mesite, chicks may remain with the parents for up to a year.

PRECOCIAL CHICKS

Some species of birds, including mesites, many wading birds, and species like chickens and ducks, have precocial chicks. Precocial chicks are developmentally advanced by the time they hatch. They are born with down feathers and are also able to move around and fend for themselves to some degree. Precocial chicks are contrasted with the altricial (al-TRISH-uhl) young of other bird species, including most songbirds. Altricial chicks are featherless and helpless when they hatch.

MESITES, ROATELOS, AND PEOPLE

All three species of mesites are well known to local humans and are hunted for food. However, in certain portions of Madagascar, the brown mesite is not hunted because it is protected by a taboo, one so strictly observed that it is forbidden to mention the bird's name.

CONSERVATION STATUS

The three species of mesites are considered Vulnerable, facing a high risk of extinction, by the World Conservation Union (IUCN). This is due primarily to habitat loss, especially the destruction of forest habitats for agricultural use, logging, or the production of charcoal. Species associated with humans, such as dogs and rats, also negatively affect some populations.

WHITE-BREASTED MESITE (Mesitornis variegata): SPECIES ACCOUNT

Physical characteristics: The white-breasted mesite, also known as the white-breasted roatelo, is about 12 inches (30 centimeters) in length. Males weigh approximately 3.5 to 4 ounces (99 to 113 grams) while females are somewhat lighter. White-breasted mesites have reddish brown backs. The throat, eyebrows, and breast are a pale cream color. The neck area is sometimes gray. White-breasted mesites also have black crescent-shaped markings scattered on the sides of the breast and upper belly.

Geographic range: White-breasted mesites are found only on the large island of Madagascar.

Habitat: Where it occurs in western and northern Madagascar, the white-breasted mesite occupies dry, deciduous forests with sandy soils. The eastern portion of its range is characterized by more humid rainforest.

Diet: White-breasted mesites primarily eat invertebrates and plant seeds. It searches for these food items in the leaf litter and low bushes.

Behavior and reproduction: The white-breasted mesite is a secretive species that is most commonly found on the ground. The species does not migrate, but remains near its breeding grounds all year. White-breasted mesites are often found in groups of approximately three individuals, frequently a male and female pair and their most recent young. White-breasted mesites are territorial, meaning individuals defend their territory from others of the same species.

The white-breasted mesite is believed to be a monogamous species. White-breasted mesites build nests 3 to 9 feet (0.9 to 2.7 meters) off the ground. Their nests are generally simple platforms of sticks. The female lays one to three eggs during the breeding period between October and April. White-breasted mesite chicks are precocial, and young remain with their parents for up to a year.

White-breasted mesites and people: White-breasted mesites are sometimes hunted for meat. Because of their small size, however, hunting occurs only irregularly.

Conservation status: The white-breasted mesite is considered Vulnerable by the World Conservation Union (IUCN). Its status is primarily due to a loss of forest habitat to logging and agricultural use. ∎

FOR MORE INFORMATION

Books:

Langrand, O. Guide to the Birds of Madagascar. New Haven, CT: Yale University Press, 1990.

Morris, P., and F. Hawkins. Birds of Madagascar: A Photographic Guide. East Sussex, U.K.: Pica Press, 1998.

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

Web sites:

"Family Mesitornithidae (Mesites)." Animal Diversity Web. http://animaldiversity.ummz.umich.edu/site/accounts/classification/Mesitornithidae.html#Mesitornithidae (accessed on March 29, 2004).

"Mesites, Roatelos." Bird Families of the World, Cornell University. http://www.es.cornell.edu/winkler/botw/mesoenatidae.html (accessed on March 29, 2004).

"Mesitornithidae (Mesites)." The Internet Bird Collection. http://www.hbw.com/ibc/phtml/familia.phtml?idFamilia=41 (accessed on March 29, 2004).