The Bobolink (Dolichonyx oryzivorus) is a small songbird found in North America. It is known for its colorful plumage and unique song. Bobolinks breed in open meadows across much of the United States and southern Canada before migrating in large flocks to southern South America for the winter. Their populations have been declining in recent decades, leading some to question if the Bobolink is becoming a rare bird. In this article, we will examine the Bobolink’s range, population trends, conservation status, and reasons for its decline in order to determine if it is indeed a rare bird.
Bobolink Range and Habitat
The Bobolink has an extensive breeding range across North America. According to the Cornell Lab of Ornithology, it breeds from southern British Columbia across central Canada and the northeastern United States, and south into eastern Oregon, Nevada, Utah, western Nebraska, Kansas, Oklahoma and northern Texas. Its wintering range is concentrated in southern Bolivia and northwestern Argentina.
Bobolinks prefer open habitats with dense, tall grasses and broad-leafed plants such as hayfields, meadows and pastures. They build nests on the ground hidden in the thick vegetation. These grassland habitats provide cover from predators as well as abundant food in the form of seeds and insects. Unfortunately, many of these grassland habitats have been converted to other uses like agriculture, reducing available nesting areas for Bobolinks.
Key Facts About Bobolink Range and Habitat:
- Breeding range extends across much of southern Canada and the northeastern United States
- Winters in southern South America
- Favors open habitats like hayfields, meadows and pastures
- Nests on the ground in dense vegetation
- Grassland habitat loss is reducing nesting areas
Bobolink Population Trends
Bobolink populations have declined significantly since the 1960s, based on data from the North American Breeding Bird Survey (BBS). According to the 2016 State of North America’s Birds report, Bobolinks declined by 65% between 1970 and 2014. The overall population trend shows a loss of 2.1% per year during that period.
Some regions have seen steeper declines than others. In eastern Canada, Bobolink populations declined by 5.5% annually from 1970-2012. In the midwestern United States, numbers dropped by 3.7% per year from 1966-2015. Smaller declines were noted in western Canada and the eastern United States.
Key Facts About Bobolink Population Trends:
- Populations decreased by 65% between 1970 and 2014
- Overall population declining 2.1% annually
- Steep declines in eastern Canada and midwestern U.S. since the 1960s
- Smaller declines in western Canada and eastern U.S.
This long-term population slump indicates the Bobolink is becoming less common across its breeding range. However, the wintering grounds in South America have not been as well monitored and population trends there are less certain.
Bobolink Conservation Status
Despite concerning population declines, the Bobolink is not globally considered a threatened or endangered species. It is classified as Least Concern on the IUCN Red List. Its large range and population size does not yet trigger more serious conservation action.
However, it has been assigned higher levels of concern by various organizations in the United States and Canada:
- State of the Birds Watch List – species with steep declines that warrant more monitoring
- Audubon – Climate Endangered: species threatened by climate change
- State listings: Endangered (IL), Threatened (VT, WI), Special Concern (IA, IN, ME, MN, MT, OH, PA, WA, WV)
At the local level, it is recognized as being at risk. But the Bobolink has not reached the threshold to be federally listed under the Endangered Species Act in the U.S. or the Species at Risk Act in Canada. Loss of individuals at the edges of its range make it less common in some areas, but the overall population remains relatively large.
Key Facts About Bobolink Conservation Status:
- Globally Least Concern on IUCN Red List
- Declining populations recognized by many state and provincial agencies
- Not federally listed as threatened or endangered
Reasons for Bobolink Decline
What factors account for the substantial reduction in Bobolink numbers since the 1960s? There are several primary threats facing the species:
Habitat Loss
The conversion of grasslands to intensive agriculture is the biggest driver of habitat loss for Bobolinks. Hayfields are mowed earlier and more frequently, destroying nests and young that can’t yet fly. Pastures are overgrazed or converted to cropland. Draining of wetlands also eliminates nesting areas. Expanding development consumes meadows and fields near cities.
Climate Change
Bobolinks time their migration and breeding carefully with peak food availability. Warming temperatures are causing their prey to emerge earlier, disrupting this synchronicity. Extreme spring storms and droughts have reduced reproductive success. Sea level rise could inundate South American coastal wintering grounds.
Pesticides
Use of pesticides and herbicides can poison bobolinks or reduce insect prey. Neonicotinoids are particularly detrimental to bird reproduction and migration.
Predation
Nest predation may increase without adequate vegetation cover and in fragmented habitats near forest edges. Free-roaming domestic cats kill millions of birds each year.
Factor | Examples | Effect on Bobolink |
---|---|---|
Habitat Loss | Grassland conversion to agriculture | Reduced nesting areas |
Climate Change | Altered timing of prey availability | Lower reproductive success |
Pesticides | Neonicotinoids | Impaired migration and reproduction |
Predation | Domestic cats | Increased mortality |
Key Facts About Bobolink Declines:
- Grassland habitat loss from agriculture is the primary threat
- Climate change disrupts migration, breeding and wintering grounds
- Pesticides poison bobolinks and reduce insect prey
- Predators like cats add to mortality
Conclusion
In reviewing the bobolink’s changing status over the past 50 years, it becomes clear that this iconic grassland bird is becoming less common and widespread. Its breeding population has declined by nearly two-thirds since 1970 based on Breeding Bird Survey data. This precipitous drop, coupled with habitat loss and threats from climate change, pesticides and predation, are all contributing to its vulnerable status. While bobolinks are still found through extensive parts of Canada and the United States, concentrated declines in certain areas and an overall population reduction of 2% annually illustrate troubling trends for the species. If these trends continue, the bobolink may warrant listing as a threatened or endangered species in the future. For now, it can be considered rare at the local level but not globally. Targeted conservation action to protect grasslands, limit pesticides, curb free-roaming cats and address climate change impacts could help reverse bobolink declines and keep them off the endangered species list.