Bobolink

Dolichonyx oryzivorus

Bobolinks reside in open country and often favor damp meadows (Martin and Gavin 1995). Typically a colonial nesting species, they place their nests on the ground in dense vegetation, usually in hayfields of grass, clover or alfalfa (Martin and Gavin 1995). Territorial males emit a jangling call, often while flying above a field they have selected for nesting. As with many grassland bird species, Bobolink numbers have declined significantly throughout their range (Peterjohn and Sauer 1995).

Code Frequency

Bobolinks are reasonably easy to detect and Atlasers often observed probable or confirmed breeding evidence for this species. These included territorial singing, courtship, fledged young and food for young. Bobolinks recorded as possible breeders might have been late migrants. Because the drab female approaches and departs the nest through thick vegetation (Martin and Gavin 1995), locating nests is extremely difficult. Only one nest was discovered during the Atlas Project.

Distribution

As expected, Bobolinks bred in northern counties. Locations in central Missouri south of the Missouri River were scattered and unexpected. Especially noteworthy were outlying breeding locations in Bates and Vernon counties. Certain years of the Atlas Project were especially favorable for Bobolink nesting because conditions were apparently too wet to mow hayfields. The resultant rank grasses are preferred by Bobolinks, and may have led them to nest in some of the outlying locations.

Average Number of Birds / 100 stops

Abundance

Bobolinks were most abundant in the agricultural regions of northeastern and north central Missouri.

Phenology

Bobolink migration peaks in mid-May (Robbins and Easterla 1992) and nesting was well underway by mid-June as evidenced by food carried to young on June 16. Although Bobolinks are usually single-brooded, they can raise a second brood. Second broods in New York have been recorded between June 24 and July 1 (Martin and Gavin 1995). A nest with Eggs: on July 10 may represent a second brood, renesting attempt or an abandoned nest.

Notes

Brown-headed Cowbird parasitism was recorded in one block. Cowbird parasitism of Bobolinks is infrequent except in Iowa (Friedmann 1963).

Breeding Evidence

Reported in 97 (8.0%) of 1,207 blocks

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