Fluttering over hayfields and meadows in summer, the male of this species produces a bubbling, tinkling song, after which it is named. The male is easily distinguished in its spring finery and is the only North American bird with a white back and black undersides (which could be described as wearing a tuxedo backwards). Before the fall migration he molts and takes on a striped brown appearance similar to the female. bobolinks with this plumage were once called "ricebirds" in the south, occasionally causing serious damage in this area in the rice fields.
North America and Canada are the bobolink’s breeding range, from British Columbia and Alberta to western Newfoundland, and south to West Virginia. There are also some isolated breeding populations in central Washington, north-east Nevada, east Arizona, Kansas, north Utah, and north-central Kentucky. Each year this species undergoes an extensive migration to South America, traveling through a great range of countries. These birds spend their winter within a more limited range, from south-west Brazil, eastern Bolivia, Paraguay, north-east Argentina to the province of Buenos Aires. They breed in semi-open and open grassy areas. In winter and during migration they are found in grasslands, freshwater marshes, and rice fields.
Spending winter in the southern hemisphere, huge, usually single-sex flocks of these birds migrate to the nesting grounds in North America. Their journey starts in early March and can take more than two months to complete, most individuals arriving in May at the nesting grounds. They migrate at night. These birds are territorial at the time of the nesting and breeding season, but generally they are very gregarious and can be found in big flocks. During migration, bobolinks make long pit stops to eat in rice fields. Being diurnal foragers, they have night-time roosts along their migration routes. These birds have songs like a bubbly laugh, warbling with short notes over a wide pitch range. A soft "chuk" is their call, while the more musical flight call is a "bink" or "bwink".
Bobolinks are polygynous, each male having a number of mates each breeding season, and they are also polyandrous, one of the first of species proven to be so: each clutch laid by a female may have several fathers. On arrival at the breeding grounds, the males vigorously compete for territories by displaying, singing, fighting, and chasing one another. In spring, from May the beginning of July, bobolinks nest in meadows and hayfields. They will often return each year to the same sites for breeding, although they may choose a new area if the previous one is no longer optimal. The females make shallow cup nests from grasses and other plants, generally in grassland on the ground. Bobolinks typically have just one brood per year. 3 to 7 splotchy, cinnamon or gray colored eggs are laid, and these are incubated for around 10 to 13 days by the female. Nestlings fledge after around 10 to 14 days, flying at about 16 days.
Habitat loss is the greatest threat to these birds. Changes in land use in North America are causing the decline of the hayfields and meadows where bobolinks breed, and in South America, agricultural land is replacing grasslands that support birds when overwintering. In the southern U.S., bobolinks are shot as agricultural pests, and they are also persecuted for this reason in South America in their wintering grounds. In Jamaica they are used for food, and in Argentina males are trapped to be sold as cage birds.
According to the What Bird resource, the total population size of the bobolink is around 11,000,000 individuals. According to the Government of Prince Edward Island (Canada) resource, the total population size of the bobolink in Canada is around 1.8 – 2.2 million breeding pairs. Overall, currently this species is classified as Least Concern (LC) on the IUCN Red List, however, its numbers today are decreasing.
Due to their diet, this species influences insect populations in grassland ecosystems.