Grassland Bird Species

Bobolink

Bobolinks, common in many hayfields throughout the Northeast, are known for their noisy bubbling songs and striking black and white plumage. Male birds are conspicuous as they fly while hovering over hayfields or perching atop a shrub or fence post to defend their territories and attract females. These farm birds were abundant at the turn of the century throughout the Northeast when hayfields and pastures dominated the landscape. Bobolinks are still distributed throughout the Northeast, but their numbers have declined notably in the past 30 years.

Life History

Bobolinks build their nests in late May and early June on the ground in a dense cover of grasses and wildflowers in hayfields, pastures, old fields, and wet meadows. Breeding dates typically range from May 25 to July 5. Therefore, mowing before mid-July can harm nesting birds and young. By late July, large groups of birds can be seen perched together on stalks of wildflowers, as they prepare for their journey south.

Bobolinks undertake one of the longest migrations of any land bird in North America. In the fall, these small birds make an extraordinary flight of approximately 6,000 miles to spend the winter in central South America (Argentina, Brazil, and Paraguay). The following spring, they return North, often to the same field they left the previous year.

Unlike many other grassland birds that require large grassland tracts, bobolinks will breed in grasslands as small as five acres. Quality and management of a hayfield are important for breeding bobolinks. Timing of hay mowing is usually the most important factor that affects breeding success.

Reason for Decline

• Reduction in field diversity. Bobolinks usually do not nest in pure legume/alfalfa fields; they prefer a mixture of grasses and wildflowers.
• More frequent field rotation. Bobolinks prefer hayfields more than eight years old, where vegetation is sparser and dominated by grass and there is a greater litter cover and a mixture of forbs and small shrubs.
• Introduction of cool-season grasses. Fields, once grown in native warm-season grasses, are now planted with cool-season varieties that allow earlier and more frequent mowing. Hay is cut up to three times per year, which does not give bobolinks enough time to raise young.

Map of distribution and abundance

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