Scientific Name: Dolichonyx oryzivorus
(Information for this species page was gathered in part by Ms. Emily Bolewitz for Biology 220M at Penn State New Kensington in Spring 2013)
The bobolink (Dolichonyx oryzivorous) is a small (seven inches long and an ounce in weight) blackbird formerly found in great numbers across the northern United States and southern Canada. Loss of natural grassland habitats in its northern breeding range along with the loss of both grassland and marshland habitats in its southern, over-wintering range has seriously reduced the population density of this species.
The bobolink has two plumage and coloration patterns. The first, seen in breeding males, is the extremely distinctive solid black underside coloration with a pattern of white above and a straw colored patch on the nape of his neck (Image: Steve Maslowski, retrieved from US Fish and Wildlife Service Digital Library). The breeding male bobolink is the only song bird that is all black below. The females (and the non-breeding males) are a rich yellow-brown color with dark brown stripes on their heads and backs. They have short, conical, “sparrow-like” bills that are darker (nearly black) in the male.
Bobolinks are omnivorous and will eat a mix of available insect and plant foods. In the summer they consume slightly more insects than plant foods, while in the winter they eat abundant plant seeds. They have a common name of the “rice bird” because of the tendency of large, migrating flocks of bobolinks to descend on rice fields and consume great quantities of the grain. Nestlings are fed caterpillars almost exclusively by the parental birds.
Migration and Territory
Mating and Reproduction
Bobolink eggs are also highly camouflaged. They are a light brown with dark brown blotches and and tend to fade into the background of the soil and litter system very well. Females typically only lay one clutch of four to six eggs in a breeding season. They can, however, in the event of a nest failure lay a second clutch of eggs. The female incubates the eggs for twelve days. Nestlings will fledge after ten more days. Both parents gather caterpillars to feed the voracious nestlings, and the full attention of the monogamous male significantly increases the chances for nestling survival.
Ground based nests are very vulnerable to predators. Many of the “usual suspects” of egg and nestling predators affect bobolink nests (including skunks, raccoons, foxes, and snakes). A surprising bobolink nestling predator is the white-tailed deer. It is not known how many nestlings are eaten by deer each year, but up to 70% of bobolink eggs and nestlings are lost to predation each breeding season.
The brown-headed cow bird is a common nest parasite for bobolinks. Not only do the female cowbirds lay their eggs in the bobolink nests, but they may also actively destroy nests in order to stimulate new nest building (and, thus, new opportunities for nest parasitism).
Bobolinks require large, open, grassland spaces in order to breed and nest. They avoid forest edges and also road edges. Habitat fragmentation may be a more significant force causing their population declines than pure habitat loss.
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This page was last updated on
July 15, 2014