{"id":3551,"date":"2018-05-03T12:54:17","date_gmt":"2018-05-03T16:54:17","guid":{"rendered":"http:\/\/pages.vassar.edu\/sensoryecology\/?p=3551"},"modified":"2018-05-08T12:16:59","modified_gmt":"2018-05-08T16:16:59","slug":"3551-2","status":"publish","type":"post","link":"https:\/\/pages.vassar.edu\/sensoryecology\/3551-2\/","title":{"rendered":"The Bobolink (Dolichonyx oryzivorus)-General Biology"},"content":{"rendered":"

The Bobolink (Dolichonyx oryzivorus<\/span><\/i>)-General Biology<\/h1>\n

APPEARANCE<\/b><\/p>\n

Male bobolinks have large, flat heads, short necks, and short tails. Males are black on the <\/span>anterior portion of head, wings, and tail. The back, scapulars, lower back, rump, and upper tail-coverts are white\/pale gray. They have a \u00a0yellow nape and a glossy black bill (which is relatively long compared to their head size.) After breeding season, the males shed their plumages and lose bill pigmentation, looking more like female bobolinks.<\/span><\/p>\n

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Male and female bobolink side by side (Inman, David. https:\/\/www.earthrangers.com\/wildwire\/take-action\/why-you-should-protect-the-bobolink\/)<\/p><\/div>\n

Females have the same flat heads, short necks, and short tails, but are a warm brown\/yellow color below, with brown and white streaking on the flanks, sides and under tail-coverts. Females have a dark eyeline, with a broad yellowish brown crown stripe bordered by brownish black stripes on either side. \u00a0\u00a0<\/span><\/p>\n

HABITAT<\/b><\/p>\n

Bobolinks are primarily found in open areas and wetlands across the northern United States and southern Canada. They prefer to nest in fields with a mixture of grasses and broad-leaved plants, like dandelions. When they migrate, they like to visit rice fields, which has earned them the nickname \u201crice birds\u201d.<\/span><\/p>\n

They have a lot of other nicknames, too, depending on geographical area. Bent (1958) writes, \u201cin New England it is sometimes called by the pretty name \u2018meadow-wink\u2019 and the less complimentary name \u2018skunk blackbird\u2019…on fall migration it is recognized as \u2018ortlolan,\u2019 \u2018reed bird,\u2019 and \u2018rice bird,\u2019 on account of its haunts and habits, and, in Jamaica, where it has grown exceedingly fat, they call it \u2018butter bird.\u2019\u201d<\/span><\/p>\n

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Male Bobolink in typical grassland habitat (Schneider, Greg. Bobolink Male in habitat. Greg Schneider Photography, Greg Schneider, 6 Jul. 2007, https:\/\/www.gschneiderphoto.com\/gallery3\/birds\/blackbirdsorioles\/bobolinks\/bobolink-habitat-field_2765_web.)<\/p><\/div>\n

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Bobolinks formerly nested in the tall-grass or mixed-grass prairies of midwestern United States and South-central Canada, but after the area was transformed for agricultural use, Bobolinks were displaced into clearings where deciduous forests used to stand.<\/span><\/p>\n

Bobolinks begin migration in early August. Eastern populations of Bobolinks typically head southeast. Western populations are smaller and not much is known about their migration path. <\/span><\/p>\n

Eastern populations migrate across the south-eastern United States, through the Carribean, and conclude in South America. They stay here from about late April to September, within a range extending through Brazil, Paraguay, and Argentina. <\/span><\/p>\n

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Map detailing the geographical range of the Bobolink. Orange is the range where the Bobolink breeds, and yellow is the range across which the Bobolink migrates.
(Published by Cornell University, https:\/\/birdsna.org\/Species-Account\/bna\/species\/boboli\/distribution.)<\/p><\/div>\n

Aside from the South American mainland, Bobolinks are known as the only migratory landbird species that stops every year in the Galapagos. During Darwin\u2019s stay in the Galapagos, he collected a single Bobolink specimen in San Cristobal. It is theorized by Perlut (2016) that Bobolinks may be a way for seeds to disperse from the Galapagos to South American mainland.<\/span><\/p>\n

After attending migration, bobolinks tend to re-nest in the same area every year.<\/span><\/p>\n

DIET<\/b><\/p>\n

In the breeding season, Bobolinks eat weed seeds, insect larvae, adult insects, and other arachnids. They feed their nestlings with invertebrates exclusively, and a meal for them can consist of Lepidoptera, sawfly, arctiid larvae, and mayflies. In May, male bobolinks eat dandelion seeds with the occasional cutworm. By June, males begin to eat cinquefoil seeds, yarrow, Canadian thistle, false lupine, dock, and mallow. <\/span><\/p>\n

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Picture of a well-known Lepidoptera, the monarch butterfly. Lepidoptera is an order of insects that include butterflies and moths.
(Published by the National Wildlife Federation, https:\/\/www.nwf.org\/Educational-Resources\/Wildlife-Guide\/Invertebrates\/Monarch-Butterfly.)<\/p><\/div>\n

When foraging for seeds, Bobolinks often perch on the tops of nonwoody plants and carefully extract seeds for ingestion. They have been observed jumping from the ground to get at mature dandelion seeds and other plants that aren\u2019t strong enough to support the Bobolinks\u2019 weight. Bobolinks tend to swallow their food whole. Following the ingestion of milky grains or insects, they will wipe their bill on nearby vegetation. <\/span><\/p>\n

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Male bobolink extracting seeds from a dandelion for consumption
(Balley, Brian. Toronto and Southern Ontario Birding. Brian Balley, 21 May 2010, http:\/\/www.outdoorontario.net\/birds\/phpBB\/viewtopic.php?p=21417.)<\/p><\/div>\n

During migration and in the winter, Bobolinks will feed on rice, oats, other small grains, tassels, weed seeds, and small insects. They look for insects on the underside of soybean and sunflower leaves. <\/span><\/p>\n

While typically daytime foragers, during migration they will feed in rice fields on bright nights, to build up fat reserves for long overwater flight.<\/span><\/p>\n

BREEDING BEHAVIOR<\/b><\/p>\n

After a flock of Bobolinks arrives at a breeding ground, the males become extremely territorial and fight for ground by singing, dancing, and chasing each other. After the females arrive, males rarely leave their territories unless it\u2019s to chase away intruders, and remain defensive until they start feeding nestlings. Females, on the other hand, are rarely aggressive towards each other and do not defend the male\u2019s territory from other females.<\/span><\/p>\n

COURTSHIP AND MATING<\/b><\/p>\n

When females pass overhead, males give obvious, short aerial song displays to get their attention. If a female lands within a male\u2019s territory, he proceeds with a repetitive courtship sequence, which includes brief song, hovering circle-flight, and abrupt drops to the ground. During the drops, the male emits 1-3 rasping <\/span>buzz<\/span><\/i> notes. If the female stays, the male repeats this sequence up to 5 times a minute for 30-40 minutes.<\/span><\/p>\n