THRASHERS AND MOCKINGBIRDS: Mimidae

PHYSICAL CHARACTERISTICS

Mimids, members of the Mimidae family, average in length from 8.2 to 12.2 inches (20.5 to 30.5 centimeters). Their plumage, feathers, is not bright or colorful. Most species are shades of gray or brown and gray with some black or whitish markings. Many have long, curved bills used for foraging for prey on the ground or in trees.

GEOGRAPHIC RANGE

Mimids are found throughout North and South America, and on a number of islands, including the Falklands, West Indies, Bermuda, the Galápagos, and some islands in the Caribbean.

HABITAT

Mimid habitats are varied. Many species prefer low and dense vegetation that provides a protective cover for nests. Those that are forest dwellers usually prefer the edge of a forest for this reason. Several species are endemic to small islands.

DIET

Because of the diversity of species in the Mimidae family, the birds eat anything from insects to animal flesh. Fruit, berries, and seeds are a common dietary staple. Some of the larger thrasher species will also eat small fish and lizards.

BEHAVIOR AND REPRODUCTION

Mimid behavior ranges from the loud and outgoing to the shy and secretive, depending on the species. The mimids, particularly the mockingbird species, are known for their song. Most are monogamous (muh-NAH-guh-mus) during the breeding season, and very defensive. Thrasher males are unique in that they share incubation (sitting on the eggs) duties with their mate.

THRASHERS, MOCKINGBIRDS, AND PEOPLE

Because of their interesting and often melodic songs and ability to mimic the calls of other birds and other environmental noises, many people enjoy having mimids nearby. However, The birds are very territorial and defend their nestlings vigorously. Some mockingbirds and gray catbirds have been known to attack people when threatened.

THE MOCKINGBIRD SONG

An amazing mimic, the mockingbird is able to imitate the songs of dozens of other bird species and incorporate them into his own call. They also mimic natural sounds around them, such as the croak of a frog or the chirp of a cricket. And mockingbirds kept as pets can repeat human and household noises, such as the ringing of a phone. The birds were popular pets in the nineteenth century. President Thomas Jefferson had one that he reportedly let fly around the White House on occasion.

CONSERVATION STATUS

The Cozumel thrasher and the Socorro mockingbird, both residents of Mexico, are on the Critically Endangered list, facing an extremely high risk of extinction. The Socorro mockingbird lives on a small island off the coast of Mexico, where the birds' numbers are dwindling due to predatory cats and grazing sheep overtaking their habitat. The Charles mockingbird, another island-dweller, is classified as Endangered, facing a very high risk of extinction, due to predators, as is the white-breasted thrasher. The population of the white-breasted thrasher is also declining due to habitat loss along with the black catbird, which is considered Near Threatened, in danger of becoming threatened with extinction. Finally, the Hood mockingbird is classified as Vulnerable, facing a high risk of extinction, due to its small population and limited range.

GRAY CATBIRD (Dumetella carolinensis): SPECIES ACCOUNTS

Physical characteristics: True to its name, the gray catbird is almost entirely slate gray, with a small patch of black on the top of its head, a black tail, black legs, and rust-colored undertail feathers. Their bill is short, straight, and black. Average size is 8.5 inches (21.5 centimeters) long with a weight of 1.3 ounces (36.8 grams). Both the males and the females of the species are similar in appearance.

Geographic range: The gray catbird can be found in southern Canada (from British Columbia to Nova Scotia) and the central and eastern United States (extending south from Canada down to northeastern Arizona in the West and to northern Florida in the East) during breeding season. This species winters on the east coast, from southern New England down through Florida and along the Gulf Coast into Central America. The gray catbird is also found in the Bahamas, Cuba, and Jamaica.

Habitat: The gray catbird is not a sociable bird, preferring to stay hidden and nest within its preferred habitat, which is dense and shrubby vegetation. Some favorite nesting areas include scrub, abandoned orchards and farmland, the periphery of forests, alongside streams and roads, under cactus pads (leaves), and occasionally within dense shrubbery in residential areas.

Diet: In the spring breeding months gray catbirds are primarily insect eaters, feeding on caterpillars, millipedes, grasshoppers, ants, spiders, and beetles. Starting with summer and into the fall, they start to incorporate more fruit into their diet, preferring grapes and other small fruits. When not foraging under the cover of vegetation, they can be seen walking along the ground using their bills to find insects.

Behavior and reproduction: Gray catbirds build nests under dense cover of scrub or thickets. Their cup-shaped nests are well concealed and woven from vines, twigs, straw, grasses, and occasional bits of paper or plastic. Soft hair and grass lines the inside. The male may help in nest construction, but it is usually the female that does most of the work. She lays a clutch of up to six blue-green eggs, which are incubated for about two weeks. Both male and female feed the hatchlings, who leave the nest about eight to twelve days after they hatch.

Gray catbirds and people: Gray catbirds tend to avoid people and are not considered an agricultural or residential pest.

Conservation status: Gray catbirds are common throughout North and South America. ∎

HOOD MOCKINGBIRD (Nesomimus macdonaldi): SPECIES ACCOUNTS

Physical characteristics: Hood mockingbirds are dull white on the chest and belly and streaked or spotted gray to brown coloring on the top. The dark wing feathers appear edged off-white. They may also have darker spots on the chest. The Hood mockingbird sports a black streak across its yellow-to-brown eyes, and has a black bill and legs.

Geographic range: The Hood mockingbird is found primarily on a small island in the Galápagos known as Hood Island (also known as Espantildeola).

Habitat: Hood Island is a low-lying, flat-topped island with primarily rocky terrain and sand and pebble beaches. The available vegetation is primarily scrub. Fresh water is scarce.

Diet: The Hood mockingbird is an omnivore, which means it eats animals as well as vegetation. The bird uses its long, curved beak to crack open seabird eggs in order to eat their contents. It will also drink blood from the wounds of other living or dead animals, and scavenge carrion (decaying animal carcasses).

Behavior and reproduction: During nonbreeding season, Hood mockingbirds travel in large groups of around forty to forage and defend their territories. In the months of March and April when nesting time occurs, they split off into smaller groups. The species are cooperative breeders, meaning many birds will share feeding duties for the young in a group, not just the parent birds. The typically breeding group is approximately five adult males and two or three adult females.

Hood mockingbirds and people: Because of their remote location, Hood mockingbirds don't encounter people except in the form of ecotourists and researchers. When they do come in contact with humans, they are said to be unafraid and will readily approach them and scavenge for food and fresh water if accessible.

Conservation status: The Hood mockingbird is classified as a Vulnerable species because of its limited range and the risk that dangerous weather pattern changes could affect its population. ∎

FOR MORE INFORMATION

Books:

George, Phillip Brandt. "Thrashers, Bulbuls, Starlings." In Reference Atlas to the Birds of North America, edited by Mel Baughman. Washington, DC: National Geographic Press, 2003.

Sibley, David Allen. National Audubon Society: The Sibley Guide to Birds. New York: Alfred A. Knopf, 2000.

Periodicals:

Clark, Gary. "A Singer and a Song; Mockingbird's Arrival is Among Area's Signs of Spring." Houston Chronicle (Feb 21, 2003): 3.

Web sites:

"BirdLife's Online World Bird Database: The Site for Bird Conservation. Version 2.0." BirdLife International. http://www.birdlife.org (accessed on May 25, 2004).

"Gray Catbird." All About Birds. Cornell Lab of Ornithology. http://birds.cornell.edu/programs/AllAboutBirds/BirdGuide/Gray_Catbird_dtl.html (accessed on May 28, 2004).