The Northern Mockingbird, a year-round resident throughout most of its range, is renowned for its complex, ebullient, mimicking song and for its pugnacious defense of territory, nest, and young. An omnivore, this species eats a wide variety of fruit and insects, favoring habitats such as park and cultivated lands, second growth at low elevations, and suburbs, where it commonly forages for insects on mowed lawns. Although this mockingbird has recently declined in the southern part of its range, it has expanded northward during the past century, a trend likely to continue as suburbs and areas of second growth spread.
Both male and female mockingbirds sing, unmated males at night. A male's repertoire often contains more than 150 distinct song types which change during its adult life and may increase in number with age. Songs are acquired through imitating the calls and songs of other birds, the vocalizations of non-avian species, mechanical sounds, and the sounds of other mockingbirds.
Northern Mockingbirds typically pair monogamously, but bigamous and polyandrous matings do occur. Some adults may spend the entire year as a pair on a single territory, while others establish distinct breeding and wintering territories.
During their first winter, mockingbirds either set up their own territory or move around together in flocks. The causes of these differences in social organization are unknown. Parental care is shared more or less equally by the sexes, although females perform all incubation and nearly all brooding of young nestlings. Mockingbirds overlap successive nesting attempts, and their temporal division of labor allows them to produce up to four broods each breeding season.
As a species that is widespread, abundant, and easily observed in human-dominated landscapes, the Northern Mockingbird has proven an excellent subject for a variety of scientific questions. Research on this species has focused on conspicuous behaviors characteristic of the species, its breeding ecology, and the exposure to new and emerging pathogens and contaminants. The conspicuous behaviors that have been most studied are singing (e.g. Dickey 1922, Wildenthal 1965, Derrickson 1988, Zollinger et al. 2008), a distinct wing-flashing behavior (e.g. Gander 1931a, Hailman 1960a, and Hayslette 2003), and vigorous nest defense (Merritt 1984, Brietwich 1988, Londono et al. 2008). Many aspects of breeding ecology have been studied including territoriality (e.g. Logan and Hyatt 1991), mating systems (e.g. Logan 1991, Derrickson 1989), the nesting cycle, and nest construction (Logan et al. 1990). Emerging research has used mockingbirds to monitor the spread of infectious diseases such as West Nile Virus (Komar et al. 2005) and blood parasites (Fokidis et al. 2008, Anderson et al. 2009), as well as monitoring environmental contaminants like pesticides (Rivera-Rodriguez et al. 2007) and lead (Roux and Marra 2007).