Bird Nest Habitat and Invasive Plants

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A Balancing Act for Sligo

A number of birds that breed in Sligo build their nests close to the ground, hidden away in dense shrubs and vines, both natives and invasives. These birds include fourteen of the most tuneful songsters of a Sligo springtime: white-eyed vireo, carolina wren, veery, wood thrush, catbird, mockingbird, brown thrasher, cardinal, common yellowthroat, kentucky warbler, and three kinds of sparrow: eastern towhee, field sparrow, and song sparrow. All are native to Sligo.

Although the shape and materials of an old bird nest are not sufficient to identify the species that built it, we can narrow down the list to the above since ornithologists know which birds build nests at low levels. (If you want to look for old bird nests, the best time is in November and December, before the winds, ice, and heavy snow of winter breaks them apart.)

Nest with rose and greenbrier, Feb 2, 2005, above soccer field bridge along dirt path

Our native common greenbrier - a thorny green vine - makes an excellent bird-nest location, and is a favorite of the gray catbird. The greenbrier's dense tangle of leaves and branches obscures the view from predators, and its sharp thorns deter those that might notice the nest. It may look messy to some, and annoy the hiker by its thorns, but a thicket of this vine is a welcome sight to a bird looking for a safe place to build its nest.

Greenbrier serves as bird cover. Parkside slope below basketball court.

Greenbrier again serving as bird cover, probably section 6 at Parkside

Our low-nesting birds are just as happy raising their young among invasive shrubs and vines as they are among native plants. Their priority is simply a good hiding place, out of view from the many hungry animals that prey on the eggs and young of birds: raccoons, opossums, snakes, foxes, hawks, owls, crows, blue jays, even snapping turtles, all of which occur in Sligo. When invasive vines and shrubs drive out native plants, birds have no choice but to build their nests among the invasives.

Nest with multiflora rose, porcelainberry, and probably mulberry. Feb. 2, 2005, along Flora Lane

Nest, perhaps in porcelainberry, at Parkside & Rose, Jan 3, 2005

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Photos by Sally Gagne. Text by Sally Gagne and Michael Wilpers.
Sources: C. Robbins, ed., Atlas of the Breeding Birds of Maryland and the District of Columbia (Univ. of Pittsburgh Press, 1996); Hilton Pond Center for Piedmont Natural History, www.hiltonpond.org; C. Dowd, "Effect of Development on Bird Species Composition in Two Urban Forested Wetlands in Staten Island, New York," J. Field Ornithology, 63/4, 1992; J. Danoff-Burg, Introduced Species Summary Project, Columbia Univ., http://www.columbia.edu/itc/cerc/danoff-burg/invasion_bio/inv_spp_summ/invbio_plan_report_home.html; M. Moran, Study of Northern Virginia Ecology, http://www.fcps.edu/StratfordLandingES/Ecology/home.htm