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Bird Ecology and Conservation Ontario
Newsletter No. 23, July 2021
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Title image_BECO News
Balancing bobolink conservation with farm production
As happens every spring, an incredible number of birds arrive in Canada, looking for breeding habitat where they can raise their young. During the first week of May, four male bobolinks arrived in an 8-acre field on a cattle and sheep farm in Grey County, one of our 2021 study sites. Each male established and began defending a territory against the other males. A week later, about eight female bobolinks arrived, having identified the grassy field as a good place to build nests and attracted by the singing males. The birds are oblivious to the nearby barn, fencing around fields, and herds of livestock in other fields on this busy farm. Most bobolinks nest in working agricultural landscapes (hayfields and pastures), leaving nests vulnerable to potential inadvertent destruction from hay harvest and livestock grazing. Thus, what happens on this particular farm during May, June, and early July will determine if the nesting bobolinks will have a chance to raise their young . . .

During the third week of May, a small herd of cattle enter the field where our small group of bobolinks are just beginning to build nests. Grassland management practices on this farm are a bit different than most. The herd remains in the field for just three days, after which they are moved to other pastures, leaving plenty of vegetation behind for the bobolinks to nest in. The field will then be left undisturbed for the rest of the bobolink nesting season, providing the birds with ample time to raise their young.
Male bobolink with damselfly_Xuan Zhang
A male bobolink with a damselfly to feed to his nestlings.
Photo: Xuan Zhang
Fast forward to today . . . The bobolinks have finished nesting in the field and any day now, when the weather is suitable, the field will be cut for hay to feed the cattle and sheep in winter. Typically, delaying a hay harvest until mid or late July means a significant sacrifice in the nutritional quality of the hay. But on this farm, wet clay soil means the hayfields mature later than on many other farms and therefore aren't cut until July. The early grazing sets the vegetation back even more, delaying the maturation of this field so that it can be cut after the other fields on the farm without sacrificing quality. The farmer alternates this practice between two hayfields to provide each field with a year's rest from the early grazing. It's a winning scenario for the bobolinks, and other grassland birds, that nest in these fields. It also happens to be what works for the particular conditions of this farm.
Bobolink nestlings_Zoe Lebrun-Southcott
4-day-old bobolink nestlings.
Photo: Zoé Lebrun-Southcott
This year, we worked with a group of farmers to continue our research into how areas for nesting bobolinks can be integrated into farm practices. We could tell a story about each farm as they are all unique with different challenges and opportunities for bird conservation. As always, we learned so much from our interactions with each farmer and the particular circumstances of each farm. Several farmers were able to implement the scenario described above, in which a field with nesting bobolinks is grazed lightly in spring and then left undisturbed while the birds are nesting; a practice we did some initial research on a few years ago and wanted to investigate further.
Female bobolink_Xuan Zhang
A few metres away, hidden under a tangle of vetch, clover, and grasses, is this female bobolink's nest.
Photo: Xuan Zhang
We monitored the nests and territories in these fields to improve our understanding of how well the birds can reproduce under this management practice. We also monitored bobolinks nesting in fields that weren't grazed or cut during the nesting season, to be able to compare nesting success under these difference scenarios.

Finding ways to leave some pastures or hayfields undisturbed during the nesting season can be a real challenge for farmers because animals need to graze and hay needs to be cut to provide forage for winter. Analyses of the data we collected this year will help us understand how the birds fare in fields where some grazing occurs early in the nesting season. Although this practice won't work for all farmers or in all pastures, it will hopefully provide an option for some farmers to help balance the needs of the birds and the grazers.
Bobolink research team_Xuan Zhang
Three members of BECO's 2021 field team at one of our study farms. From left to right: Emma Lachance Linklater, Andrew Campomizzi, Zoé Lebrun-Southcott.
Photo: Xuan Zhang
It's hard to believe we're almost at the end of another bobolink breeding season. Trying to keep pace with the flurry of bobolink nesting activity makes the time fly by. Nearly all of the bobolink nesting activity is now complete, but this morning, we checked on our last three active nests. The first one was empty, but the female was carrying food to a location only metres away from the nest—the young had just fledged. The other two nests were still active, both with three 9-day-old nestlings. As long as these late nests aren't located by predators, these young bobolinks should be out of the nest in one to two days.

In most fields, the nesting is finished and family groups, as well as those that didn't nest successfully, are gathering together in flocks. As the bobolinks begin getting ready to migrate back to South America, we are starting to pack up our gear and look at the data we've gathered. The fields are already eerily quiet compared to the cacophony of bird song in June from all of the species nesting in the grass and on the field edges. The amount of life and activity in these agricultural grasslands in spring and summer never ceases to amaze us.
Bobolink flock_Zoe Lebrun-Southcott
On July 16, a flock of more than 60 bobolinks lined the fences of this hayfield where the harvest was delayed to allow the birds a chance to nest successfully.
Photo: Zoé Lebrun-Southcott
To all of the farmers who participated in BECO's 2021 grassland bird project . . . thank you for welcoming us onto your farms and allowing us to study the birds in your fields. We are truly grateful for your interest in bird conservation and your contributions to this work.
Moving the cattle_Zoe Lebrun-Southcott
Calvin Cooper lets the herd into a new area of pasture.
Photos: Zoé Lebrun-Southcott
Moving the catte_Zoe Lebrun-Southcott
Funding for BECO's 2021 grassland bird research was provided by the Government of Ontario, the Ontario Trillium Foundation, ECO Canada, The McLean Foundation, the Government of Canada's Canada Summer Jobs program, and our generous donors.

This project has received funding support from the Government of Ontario. Such support does not indicate endorsement by the Government of Ontario of the contents of this material.
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