Mimus polyglottos

The Northern Mockingbird breeds from southern Canada throughout the United States and south in Mexico to Oaxaca and Veracruz. It has been introduced and established in the Hawaiian Islands and in Bermuda (Am. Ornithol. Union. 1998). Originally an inhabitant of the South, it has expanded northward in the 20th century and is still local and sporadic in the northern part of its range. The North American Breeding Bird Survey (BBS) has shown the Northern Mockingbird is more common in Texas than in any other state. The three highest BBS route totals in the United States and Canada, 224.4, 163.2 and 147.4 individuals per route were obtained in Palo Pinto, Wells and Wilbarger counties (Price et. al. 1995).

DISTRIBUTION: The Northern Mockingbird is nearly ubiquitous in Texas, being absent only from the higher mountains and forest interiors. The many “empty” latilongs in the western half of the state, especially in the Trans-Pecos, are doubtless due to lack of access as well as a paucity of observers. Throughout Texas, mockingbirds are found along roadsides, near country houses, in cemeteries, gardens, yards and streets of towns and cities (Oberholser 1974). In north central Texas they may be more abundant near human habitations than in the countryside (Pulich 1988) and this is also the case in the western part of the state. In extensive farmlands, the treeless plains and the arid Trans-Pecos they occupy brushy thickets and isolated mottes, In Big Bend National Park mockingbirds frequent almost every wash and patch of vegetation from the floodplain to the lower edge of the Chisos woodlands (Wauer 1985). In pine and pine-hardwood forests in east Texas, mockingbirds are present in stands of small pine saplings, but are absent from stands of larger frees (Dickson and Segelquist 1979). Mockingbirds are most abundant in the brushlands of south Texas where BBS routes record more than 100 mockingbirds per 40 km (25 mi) annually (Sauer et al 2005).

SEASONAL OCCURRENCE: Mockingbirds are generally considered a “resident” species and this is undoubtedly true of many individuals. However, fruit is an essential item in their winter diet and they protect winter territories which contain the resources to carry them through the winter (Safina and Utter 1989). In habitats lacking these resources, especially the plains and the arid southwest, considerable shifting between breeding and winter territories occurs. To find an unclaimed territory, mockingbirds may move no farther than the nearest city garden which has a supply of berry-bearing ornamental shrubs or trees, or they may travel many miles. Banding studies show some individuals travel up to 800 km (500 mi; Cooke 1946).

There are many anecdotal accounts of Northern Mockingbirds including in their earliest spring songs the vocalizations of species which occur far to the south of the locale of the singer, an indication that the singer has recently done some traveling. For example, in Austin, Texas, April 16, 1962, a mockingbird repeatedly sang songs of Plain Chachalaca (Ortalis vetula), Groove-billed Ani (Crotophaga sulcirostris), Couch’s Kingbird (Tyrannus couchii), Great Kiskadee (Pitangus sulphuratus) and Green Jay (Cyanocorax yncas), species which live 440 km (275 mi) south of Austin (Oberholser 1974). Northern Mockingbirds are famous for their complex songs. A male’s repertoire often contains more than 150 distinct song types. These may imitate calls and songs of other birds, vocalizations of non-avian species and mechanical sounds (Derrickson and Breitwisch 1992). Males sing from early February into late summer, then again when they establish fall territories.

Females rarely sing during the breeding season, but do sing during the fall. Unmated males may sing all night, especially at the time of the full moon (Derrickson and Breitwisch 1992).

During the TBBA years (1987-1992), nests with young were found as early as March 25 (latilong 26098) and as late as July 30 (latilong 33096). Nests with eggs have been reported, without locations from March 6 to August 25 and young just out of the nest as late as October 19 (Oberholser 1974).

BREEDING: HABITAT: Mockingbirds nest in a great variety of shrubs and trees. The majority of nests are located in dense shrubbery or thickly-leafed trees which provide optimum concealment. Early nests which are begun before deciduous trees have leafed out are built in evergreen trees and shrubs. In south Texas, spiny shrubs are utilized and Fischer (1981) theorized such shrubs provide greater protection from predators. Nests are constructed with a heavy outer layer of loosely assembled, often thorny, twigs. An inside compact layer of various easily available materials, including dry leaves, plant stems, paper, cotton or hair is placed inside the outer layer. The lining is of small rootlets or fine grasses. Nest heights vary from as high as 6 m (19 ft) to as low as 50 cm (20 in), but are generally between 1 and 3 m (3-10 ft; Laskey 1962). In south Texas, higher nests had a greater percentage of successful fledging (Fischer 1981). Three to five eggs are laid. Two or three broods per season are raised, even in the northern parts of the range (Sprunt 1964). In Texas, four broods are common.

Parasitism by Brown-headed Cowbirds (Molothrus ater) is infrequent, and the Bronzed Cowbird (M. aeneus) has only occasionally parasitized mockingbirds in Texas (Friedmann et al 1977). Tn south Texas, predators took 55% of nests observed, with snakes as the major offenders (Fischer 1981). Other possible nest predators include Greater Roadrunners (Geococcyx californianus), jays, crows and ravens (Corvus spp.), Great-tailed Grackles (Quiscalus mexicanus) and opossums.

STATUS: Data from 199 Breeding Bird Survey routes in Texas indicate a stable mockingbird population from 1980-2005 (Sauer et al 2005). The mockingbird is well suited to be the State Bird of Texas. It is widespread, abundant, easily recognized, an ebullient songster, and lives willingly, if not always amicably, among people and their domestic animals.

Text by Frances C. Williams* (posted with updates 2007)
*Deceased

Literature cited.

American Ornithologists’ Union. 1998. Checklist of North American birds, 7th ed. Am, Ornithol. Union, Washington, DC.

Cooke, M. T. 1946. Wanderings of the mockingbird. Bird-Banding 17: 784.

Derrickson, K.C. and R. Breitwisch. 1992. Northern Mockingbird. (Mimus polyglottos) In The birds of North America, No. 7 (A. Poole, P. Stettenheim, and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.

Dickson, J. O. and C. A. Segelquist. 1979. Breeding bird populations in pine and pine-hardwood forests in Texas. J. Wildl Manage. 43: 549-555.

Fischer, D. H. 1981. Factors affecting the reproductive success of the Northern Mockingbird in South Texas. Southwest. Nat. 26: 289-293.

Friedmann, H., L. F. Kiff and S. I. Rothstein. 1977. A further contribution to knowledge of the host relations of the parasitic cowbirds. Smithson. Contrib. Zool. 235.

Laskey, A. R. 1962. Breeding biology of mockingbirds. Auk 79: 596-606.

Oberholser, H. C. 1974. The bird life of Texas. University of Texas Press, Austin.

Price, J., S. Droege, and A. Price. 1995. The summer atlas of North American birds. Academic Press, New York.

Pulich, W .M. 1988. The birds of north-central Texas. Texas A&M University Press, College Station.

Safina, C. and J. M. Utter 1989. Food and winter territories of Northern Mockingbirds. Wilson Bull. 101: 97-101.

Sauer, J. R., J. E. Hines, and J. Fallon. 2005. The North American Breeding Bird Survey, results and analysis 1966-2005. Version 6.2 2006. USGS Patuxent Wildlife Res. Cnt., Laurel, MD .< http://www.mbr-pwrc.usgs.gov/bbs>

Sprunt, A., Jr.. 1948. Mimus polyglottos polyglottos. Eastern Mockingbird In Life histories of North American nuthatches, wrens, thrashers, and their allies, pp. 295-315 (A. C. Bent, ed.). U. S. Natl. Mus. Bull. 195.

Wauer, R. H. 1985. A field guide to birds of the Big Bend (rev. ed.). Texas Monthly Press, Austin.