Biodiversity in Ontario's Greenbelt (PDF) - David Suzuki Foundation

Bobolink: Coexisting can be a delicate balance
Losses of about 65
per cent of the bobolink
population since 1968, with
the most significant declines
of roughly seven per cent per
year over the last decade,
prompted its 2010 provincial
listing as threatened.
photo by Kelly Colgan Azar via flickr
Humans and other animals often develop symbiotic relationships, particularly when the loss of
natural areas pushes them into increasingly tight quarters. Given the rate of habitat loss and the
close quarters shared by humans, plants and animals in southern Ontario, it is interesting to examine
a species that relies on and is threatened by human activity: the bobolink.
The bobolink is a small bird with a native habitat of grasslands and open meadow ecosystems.
Though small populations were present in Ontario before European settlement, most bobolinks lived
in western North America. Increasing conversion of forested land in Ontario to agriculture, combined
with development of native grasslands in Western Canada and the United States, spurred a slow
eastward movement of many of the western populations of bobolink. Now, the bobolink is present
in farmers’ fields across Ontario. Though it is still relatively widespread in the area, losses of about
65 per cent of the bobolink population since 1968, with the most significant declines of roughly
seven per cent per year over the last decade, prompted its 2010 provincial listing as threatened.
Without the conversion of forests to agriculture, the bobolink could never have established
such a large population in Ontario, yet its most significant threats have been caused by changes in
market forces and technological advances in that same industry. Key threats to the bobolink in the
Greenbelt and the rest of Ontario include a second wave of habitat loss that began in the mid-20th
century, when working farms began converting to crops such as soybeans and alfalfa, resulting in
the loss of crops that could serve as replacement grasslands. 46 As well, bobolink nests are vulnerable
to haying that occurs before their young have fledged — warmer springs with less precipitation and
advancing agricultural technology have allowed haying to begin before the bobolink breeding season
is completed, possibly resulting in increased mortality of the species. 47
Tallgrass prairies are recognized in the natural heritage system of the Greenbelt, which is crucial
if remnant patches are to persist within the plan area. For species like the bobolink, which use farm
fields as habitat, the efforts of farmers and landowners within the Greenbelt will also likely play an
important role in the species’ survival and recovery. Bobolink populations are particularly strong
along the central and northern Niagara Escarpment. 48
46 E. K. Bollinger and T. A. Gavin. 1992. Eastern Bobolink populations: Ecology and conservation in an agricultural
landscape. pp. 497–506 in Ecology and Conservation of Neotropical Migrant Landbirds. J. M. Hagan III and
D. W. Johnston. (Eds.) Smithsonian. Washington, DC.
47 Bollinger and Gavin. Eastern Bobolink populations.
48 Cadman, M.D., D.A. Sutherland, G.G. Beck, D. Lepage, and A.R. Couturier (eds.). 2007.. Atlas of the Breeding
Birds of Ontario, 2001–2005. p.587.
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Biodiversity in Ontario’s greenbelt