Bobolink

Credit: Jim Gardner

Dolichonyx oryzivorus

Federal Government status: Threatened

Provincial Government status: Threatened

Have you seen this species at risk? Report your sighting.

Description

During the breeding season, the males are black with bold white patterns on their back and a patch of yellow at the back of the neck. The bobolink is the only songbird who is solid black below and largely white above. During the non-breeding season the males and females look very similar; they are straw coloured with dark stripes on the crown and back.
It is a member of the blackbird family but its bill and body shape is more sparrow-like.
The bobolink is 15-21 cm in length.

Male bobolinks’ joyous, bubbling songs announce their arrival in Ontario in mid-May when they quickly establish their territories. The females join about a week later. Males defend their territory aggressively by singing and chasing away rival males.
A male will often mate with several females in his territory. He will only help with feeding the young in his primary nest. Usually younger birds of either sex that have not paired off will assist in feeding other nestlings.
Bobolinks build their nests on the ground, hidden in long grass. The females lay three to seven greyish eggs speckled with reddish brown. Incubation takes approximately 13 days. The fledglings leave the nest at about 10 days old however; they are unable to fly a sustained distance until they are 16 days old.
Their summer diet consists mainly of insects, including beetles, grasshoppers, caterpillars, wasps, ants, spiders and millipedes. They also eat some weed and grass seeds. During migration, they feed heavily on rice and millet, and are considered a major agricultural pest in regions where these crops are grown.
Bobolinks migrate to the grasslands of southern South America – a round trip of approximately 20,000 kilometres.

The species is threatened by incidental mortality from agricultural operations, habitat loss and fragmentation, pesticide exposure and bird control at wintering roosts. According to the Quebec-based Migration Research Foundation, 96 percent of eggs and nestlings are destroyed during early hay cropping, either killed by mower blades or scooped up by gulls and other predators when the grasses are cut.
Between 1968 and 2008, bobolink numbers have declined by 65 percent.
Mid- to late June, the hatchlings are at their most vulnerable. A delay in cutting hay crops until the second week in July would allow the baby bobolinks to fledge.