Identification and Behaviors
Arrival to Breeding Grounds – Month of May
After travelling approximately 10,000 km from southern South America, Bobolinks return to Ontario between May 1st and 30th. Males arrive at the breeding grounds about one week before females. They establish a territory and begin singing their territorial song. Agricultural – or surrogate – grasslands are the most important driver for grassland breeding birds today and will likely continue to be into the future (Environment Canada, How Much Habitat is Enough? Third Edition, 2013). As a migratory bird, Bobolink span a large geographic range and so there are many potential sources responsible for the decline. Bobolink depend heavily on grasslands including hay and pasture fields for breeding habitat in Ontario. Bobolink populations are decreasing rapidly. Reasons for this decline might include: declining insect populations, the loss of appropriate breeding habitat and destruction of nests and young when hay fields are cut during nesting season.
Courtship and Breeding – Mid-May
Bobolink pair formation (finding a mate) occurs in mid-May. Males attract females by performing their characteristic aerial display flights over fields. Breeding males repeatedly fly up, rising slowly on rapidly-vibrating wings singing their bubbling sound, before descending. Males move like a helicopter, flying in space slowly with quickly beating wings. View male aerial display flight here:
On the ground, males attract mates by spreading their tail, drooping their wings and pointing their bill down to display their yellow head to females. Males are very vocal when establishing territory and courting females. Look for males singing from exposed fence posts during breeding season. Listen for a series of happy, bubbling, gurgling phrases with a combination of sharp high notes and buzzy low pitches. Each song is approximately 3.5 seconds long. Males will also give buzzing calls during courtship.
Nesting- Late May
We recommend keeping away from potential nest areas as the nests are very well hidden and fragile, and can be destroyed if stepped on.
Hatching – Mid-June
In mid-June (11-13 days after eggs are laid) Bobolinks will hatch. While in the nest, these young birds are called nestlings. Nestlings initially have closed eyes and are naked aside from some sparse yellow down. Nestlings lack flight feathers and are dependent on their parents for food. Bobolink calling tapers off by mid-June when eggs have hatched and caring of young begins.
Caring for nestlings – Mid-June to early July
Nestlings are fed exclusively insects by both parents. During this life stage, adults can be observed carrying insects to their nests. Food being carried is most likely being delivered to young because Bobolinks do not carry food to incubating mates. Adults can also be observed carrying faecal sacs (a mucous membrane that encloses the feces of nestlings) away from the nest.
Female Bobolink carrying an insect to feed her young
Photo credit: Gerald Morris
Fledging – Early July
Most Bobolinks leave the nest (fledge) by early July (8-14 days after hatching) usually before they know how to fly. Young birds fledge when they have developed enough muscle mass and initial flight feathers required to fly. Fledglings still depend on their parents for food for 10 days after leaving the nest.
Fall Migration – August 20 - September 20
Bobolinks begin their migration back to their winter habitat from August 20 - September 20.
Feeding throughout breeding season
Bobolinks forage for insects and seeds both on the ground and while perched up in grass and weed stalks. Throughout breeding season Bobolinks eat primarily seeds and insects.
Photo credit: Gerald Morris
Martin, S., & Gavin, T. (1995). Bobolink (Dolichonyx oryzivorus). Ithaca, New York: Cornell Lab of Ornithology.
McCracken, J., Reid, R.A., Renfrew, R., Frei, B., Jalava, J., Cowie, A., et al. (2013). Recovery Strategy for the Bobolink (Dolichonyx oryzivorus) and Eastern Meadowlark (Sturnella magna) in Ontario. Peterborough, Ontario: Ontario Recovery Strategy Series.
Ontario Breeding Bird Atlas. (2001). Guide for Participants. Don Mills: Atlas Management Board, Federation of Ontario Naturalists.
The Cornell Lab of Ornithology. (2015). Bobolink. Retrieved from all About Birds: https://www.allaboutbirds.org/guide/Bobolink/id