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Common Name: Northern Mockingbird
Scientific Name: Mimus polyglottos

(Information for this species page was gathered in part by Ms. Christine Patroski for Biology 220W at Penn State New Kensington during Spring Semester 2013)

Northern mockingbird - image credit Ryan Hagerty, US Fish and Wildlife Service Digital LibraryThe northern mockingbird (Mimus polyglottos) is a “robin sized” song bird that is nine to ten inches long with a thirteen to fifteen inch wingspan. It has a gray body that is lighter on its chest and belly with white patches on its wings, a long, thin bill that is slightly downwardly curved, and long legs.

Image credit: Ryan Hagerty, US Fish and Wildlife Service Digital Library.

It is found throughout the United States, Mexico and Central America except for the northern-most far West and northern-most Midwest states. Summer breeding ranges extend a bit further into these northern regions. Birds that breed in the north tend to migrate south for winter, while those that breed in the south tend to stay in place for the winter.
Northern mockingbirds and very well adapted to human-modified ecosystems and are, almost without exceptions, even more abundant in urban and suburban settings than in a purely rural environment. Protection from predators in these human systems is a commonly discussed explanation for these observations.

Northern mockingbirds are known for the range and vigor of their songs. Males add songs to their repertoires throughout their lives and may be able to sing up to two hundred song patterns. They imitate each other, they imitate other birds, they imitate other animals and even imitate human-generated song and noise patterns (car alarms, bus signals, train crossing warnings etc). They sing all day and can even sing on into and through the night (the night singers are mostly unpaired males). Males sing to attract females, to declare territories and, according to many observers, seemingly for the sheer joy of singing. In addition, and in great contrast with most other song birds, even the female northern mocking birds sing!

In 2010 while we were hiking the Baker Trail we came across a male, northern mockingbird high up in the bare branches of an old ash tree near an old house in Redbank Township. He was somewhere in the middle of his mid-morning concert program and was singing his heart out to the surrounding woods. I listened to him for more than fifteen minutes and never heard him repeat or even overly dwell on any single musical phrase. As we walked on along our trail I heard his song continue for several more minutes. Song diversity and volume are very important mate selection characteristics for female northern mockingbirds. I have no doubt that this individual was vigorously passing along his genes!

Habitat and Diet
Northern mockingbirds prefer mixed habitats with open, grassy areas for ground feeding, dense shrubs and trees for protection and nest building, and abundant fruit trees and bushes for food. Parks, agricultural fields and edges, suburban lawns and fields, and forest edges are all utilized by the northern mockingbird as nesting and feeding habitats. They eat a wide range of insects and other invertebrates in the summer and primarily fruit in the winter. They are also known to drink tree sap from cut branches and scarred bark.

Mating and Reproduction
Males stake out and vigorously defend their mating territories in the spring. Females then form monogamous pair bonds with that year’s male. Unpaired males may try to slip into the territory to mate with the female, but the attention of the territorial male is very intense. Males may use wing flashings to suddenly display their white wing bars in attempts to startle and frighten other males. There are a few suggestions in the literature that this wing flashing behavior may also be used while hunting insects although its efficacy in startling an insect is not at all apparent.

Nests are built usually high in trees (ten to sixty feet off of the ground). Males build numerous starting nest foundations of twigs within their territories and the female chooses one on which to build the finished nest. The inner lining of the nest is soft and dominated by mosses and leaves (and also often a great variety of other materials like foil, plastic, and even cigarette filters). Active nests are observed in Western Pennsylvania from early March to early August. Two and sometimes even three clutches may be attempted in a given breeding season.

Females lay between two and four eggs per clutch and incubate each batch of eggs for twelve to thirteen days. Both the male and the female feed the nestlings for another twelve to thirteen days until the nestlings fledge. If, however, the female is to lay a subsequent clutch, she does so right at the hatching of the first set of eggs, and the male assumes full responsibility for the feeding and care of nestlings and young fledglings.

Northern mockingbird eggs and nestlings are preyed upon by the wide range of nest predators (including raccoons, snakes, squirrels, blue jays, crows, and more). Hawks are common predators of fledgling and adult northern mocking birds. Brown-headed cow birds readily parasitize northern mockingbird nests with their eggs and large, aggressive hatchlings.

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This page was last updated on July 20, 2014  

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