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    Bobolink Life History

    Habitat

    Habitat GrasslandsBobolinks breed in open areas across the northern United States and southern Canada, preferring large fields with a mixture of grasses and broad-leaved plants like legumes and dandelions. They formerly nested mainly in tallgrass and mixed prairie of the midwestern United States and south-central Canada. They now also nest in eastern hayfields and meadows, which became available as eastern forests were cleared, and west of the Great Plains in recently irrigated habitats. After breeding, Bobolinks move to freshwater marshes and coastal areas to molt before migrating. Their main wintering area is in the southern interior of South America, where they spend their time in grasslands, marshes, rice fields, and sorghum fields.Back to top

    Food

    Food SeedsDuring the breeding season, Bobolinks eat weed seeds, insect larvae, adult insects, spiders, and other arachnids. They feed their protein-dependent nestlings with invertebrates exclusively. They forage for seeds at the tops of nonwoody plants, often perching on the plant itself while extracting the seeds slowly and carefully. They glean insects and spiders closer to the base of the vegetation. During migration and winter, Bobolinks eat wild and domesticated rice, oats, other small grains, corn, tassels, weed seeds, and occasional insects. Normally daytime foragers, they may feed after dark on bright nights during migration, to build fat reserves for their long flight over the Gulf of Mexico and the Caribbean.Back to top

    Nesting

    Nest Placement

    Nest GroundWithin the male’s territory, the female chooses a nest site on the ground, usually on wet soil at the base of large nonwoody plants like meadow rue, golden alexander, or clover.

    Nest Description

    The female gathers materials from within about 100 yards of the nest and builds the nest by herself in 1–2 days. She starts the nest by plucking bare a patch of soil and making a depression. She weaves a floorless outer wall of coarse dead grasses and weed stems, then lines the inside by placing fine grasses and sedges directly on the soil. She may continue adding lining material after laying the first egg. The inside of the nest measures 2.4-4.3 inches across and up to 2 inches deep.

    Nesting Facts
    Clutch Size:3-7 eggs
    Number of Broods:1-2 broods
    Egg Length:0.8-0.9 in (2-2.3 cm)
    Egg Width:0.6-0.7 in (1.5-1.7 cm)
    Incubation Period:11-14 days
    Nestling Period:10-11 days
    Egg Description:Pale bluish gray to reddish brown, with irregular spots of brown and lavender.
    Condition at Hatching:Helpless, with closed eyes, and nearly naked except for sparse yellowish down.
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    Behavior

    Behavior Ground Forager

    Bobolinks are polygynous, meaning each male mates with several females per breeding season. But they are also polyandrous, with each clutch of eggs laid by a single female often representing multiple fathers. Outside of the nesting season Bobolinks live socially in flocks. After arriving on the breeding grounds males compete vigorously for territories by singing, displaying, fighting, and chasing each other. In the male’s primary nest, both parents feed the young, and in his secondary nests he may help with feeding to varying degrees. In some nests, the nestlings are fed by more than two attending adults, which possibly include multiple fathers or offspring from the previous year. The young leave the nest unable to fly, and hide in thick vegetation for a few more days until their flight feathers have fully emerged. Families from several nests join together and form foraging flocks. Within about a month the immature birds learn to feed themselves, and the flock departs the breeding grounds soon afterward.

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    Conservation

    Conservation DecliningAlthough Bobolinks are numerous and adaptable, their U.S. population declined by over 2% per year between 1966 and 2015, resulting in a cumulative decline of 65%, according to the North American Breeding Bird Survey. Partners in Flight estimates a global breeding population of 8 million, with 28% breeding in Canada, and 72% spending some part of the year in the U.S. The species rates a 14 out of 20 on the Continental Concern Score and are on the 2016 State of North America's Birds' Watch List, which includes bird species that are most at risk of extinction without significant conservation actions to reverse declines and reduce threats. People have shot Bobolinks as agricultural pests in the southern United States, trapped and sold them as pets in Argentina, and collected them as food in Jamaica. But the main reason for the Bobolink’s decline is land-use change, especially the loss of meadows and hay fields. To improve the Bobolink’s prospects, people can maintain its breeding habitat by mowing fields annually once nestlings have fledged, and managing natural prairies through prescribed burning.Back to top

    Backyard Tips

    If there’s breeding habitat of grassy pasture or overgrown fields near your home, Bobolinks may visit open yards to forage on seed-bearing weeds.

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    Credits

    Dunne, Pete. 2006. Pete Dunne's essential field guide companion: Houghton Mifflin Harcourt.

    Partners in Flight. 2017. Avian Conservation Assessment Database. 2017.

    Renfrew, Rosalind, Allan M. Strong, Noah G. Perlut, Stephen G. Martin and Thomas A. Gavin. 2015. Bobolink (Dolichonyx oryzivorus), version 2.0. In The Birds of North America (P. G. Rodewald, editor). Cornell Lab of Ornithology, Ithaca, New York, USA.

    Sauer, J. R., D. K. Niven, J. E. Hines, Jr. Ziolkowski, D. J., K. L. Pardieck, J. E. Fallon and W. A. Link. The North American breeding bird survey, results and analysis 1966-2015 (Version 2.07.2017). USGS Patuxent Wildlife Research Center 2017.

    Sibley, David Allen. 2014. The Sibley guide to birds, second edition. Alfred A Knopf, New York.

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