Bird Ecology and Conservation Ontario
Newsletter No. 9, September 2017
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Bobolink research in the Ottawa Valley
Female Bobolink carrying food
A female Bobolink, with a beak full of insects, watches alertly for danger before delivering the food to her young.
Photo: Jennifer Horvat
Last day of the field season

“On Sunday, July 23rd, I walked through the waist-high grass of an un-grazed 44-acre cattle pasture to check on the status of our only remaining active Bobolink nest of the season. When I checked the nest, it was empty. I backed away and knelt in the grass to conceal myself as I watched for clues about the fate of the nest. As it had done so many times this spring and early summer in the Ottawa Valley, it started to rain. Fortunately, the birds stayed active, despite the weather. I saw a female Bobolink carry food three times over the next 45 minutes, once to within a few metres of the nest and twice to about 40 metres away. Our 89th Bobolink nest of the season had fledged young birds.”
-    Andrew Campomizzi, Research Scientist
Marking a nest in the field
Monica Fromberger and Gerald Morris flag the location of a late-season nest. Markers are placed a few metres away, to avoid potentially attracting predators to nests.
Photo: Jennifer Horvat
Thanks to generous farmers and our tenacious field staff, we had a successful second field season studying Bobolink in the Ottawa Valley. By monitoring the breeding status of 112 Bobolink territories on 11 cattle farms, we collected the necessary data for our projects, including our two primary questions about how these ground-nesting birds and cattle can better coexist on rotationally-grazed farms. This was the second year we worked with farmers to provide un-grazed refuges for Bobolink in rotationally-grazed cattle pastures. Again this year, the birds were able to build nests and fledge young from the small refuges. Depending on the number of cattle and duration of grazing, some nests were trampled in grazed pastures.
Cattle on a rotationally-grazed farm
Cattle on one of the rotationally-grazed farms we worked on this year.
Photo: Andrew Campomizzi
In 2017, we also asked a new question: can Bobolink tolerate some light grazing by cattle early in the breeding season and still fledge young? We saw some evidence that it might be possible. We worked with farmers to identify pastures that their cattle could graze during late May and early June at about half of the normal grazing pressure. The Bobolink arrived in these pastures after migration and established territories. The cattle entered shortly afterwards and began grazing. In some cases, the Bobolink remained in the pasture, in others, some birds moved to an adjacent field.

After the cattle left, we found that most nests had not been trampled. Some of the birds that had vacated the field returned to build a new nest and most birds whose nests had been trampled remained and built new nests. More than half of the Bobolink nests in these lightly grazed pastures subsequently fledged young, even though the vegetation was shorter than in un-grazed fields (which could expose the nests to predators).
Bobolink nest with 1-day-old young
A Bobolink nest with 1-day-old young.
Photo: Gerald Morris
Now that we have the data on nesting Bobolink and cattle grazing for both experiments, we’ll begin analyzing to assess what we’ve learned and how different grazing practices can provide nesting areas for the birds. There’s still a long way to go to identify farming practices that are both compatible with Bobolink nesting and viable for farmers, but we’re learning more each year and making progress toward supporting the conservation of these gregarious birds.
Testing grazing strategies for Bobolink in pastures is a collaboration with the Ontario Soil and Crop Improvement Association. Funding is provided by the Government of Canada through the Species at Risk Partnerships on Agricultural Lands initiative. Additional assistance for this project was provided by the Government of Ontario.

BECO’s 2017 Bobolink research is also supported by Echo Foundation, Trent University, Vortex Canada, and individual donors.
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