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Bird Ecology and Conservation Ontario
Newsletter No. 20, August 2020
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Grassland bird research at the Grey-Dufferin Community Pasture
Earlier this week, we conducted our last survey of nesting grassland birds at the Grey-Dufferin Community Pasture. Needless to say, BECO's 2020 field season did not go as expected. Our decision to temporarily suspend all field activities in early spring due to COVID-19 meant that much of our planned field research was postponed until 2021 and the three field biologists we had hired to assist with field work spent most of the season working on other projects remotely from home offices.

Luckily, as restrictions began to ease in late May, we were able to begin field work at one study site, the Grey-Dufferin Community Pasture. Located northwest of Orangeville, the community pasture is an impressive grassland, nearly 600 acres, which provides grazing opportunities for local cattle farmers, supporting approximately 600 cattle through rotational grazing from May to September. It also provides a significant amount of wildlife habitat, primarily for grassland species, but in addition the property includes forested, wetland, and riparian areas.

Originally, we had planned to just monitor bobolinks in the community pasture this year. However, because the community pasture became our only study site for 2020, we decided to expand our research to include eastern meadowlarks and Savannah sparrows. All three of these species nest on the ground in hayfields, pastures, and other grasslands, and all three have steeply declining populations in Ontario.
Savannah sparrow nestlings
A Savannah sparrow nest at the community pasture.
Photo: Zoé Lebrun-Southcott
Using transect surveys, spot mapping, and nest monitoring, our goal was to gather information about where the birds were nesting, how many breeding territories there were, and how cattle grazing impacted nest success because ground nests are vulnerable to direct (trampling) and indirect (removal of vegetation) effects of cattle.

To monitor eastern meadowlarks, we used spot mapping and nest monitoring, visiting each of the ~20 territories across the pasture once per week throughout the breeding season to track behaviour and nesting status. Many territories overlapped each other and had more than one nesting female. Additionally, territory boundaries shifted as cattle grazed particular areas, but with weekly visits from late May through mid-August we were able to capture an overview of the nesting story in each territory.

To monitor bobolinks, we conducted multiple transect surveys and targeted spot mapping to assess breeding in a sample of territories during the peak of the nesting season. For Savannah sparrows, we spot mapped a sample of territories in mid-June in grazed and un-grazed fields and we opportunistically monitored nests. Savannah sparrows are numerous across the pasture; therefore, we frequently observed behaviours indicative of a nearby nest as we walked through the grass, such as a bird flushing from the ground or the sounds of mature young begging for food.
Male bobolink perched on fence post
A male bobolink perched on a fence post is easily spotted and counted on a survey. Those hidden in the grass aren't as easy to detect, unless they are vocalizing.
Photo: Zoé Lebrun-Southcott
In June, Ryan Hill, one of our field biologists, joined us in the pasture to help with a particularly busy period of data collection, including vegetation sampling to gather information about characteristics such as height, density, and ground cover composition in grazed and un-grazed fields. These data will help us understand the relationship between vegetation characteristics and field use by the birds, before and after grazing occurs.
Ryan Hill collecting vegetation measurements
Ryan Hill, BECO Field Biologist, collecting vegetation measurements in one of the 22 fields in the community pasture.
Photo: Zoé Lebrun-Southcott
In July, Octavia Mahdiyan and Xuan Zhang, the other two members of BECO's field team, each visited the pasture to see the landscape and learn more about the relationship between ground-nesting grassland birds and pasture management. Octavia and Xuan have spent much of the summer collaborating, remotely, on a data analysis project to investigate the loss of grasslands (primarily hayfields and pastures) in Ontario and factors that may be influencing this decline. As hayfields and pastures disappear, so too does important nesting habitat for grassland birds. Having a better understanding of where and why grasslands are being lost could help with conservation efforts.
Andrew and Zoé in the field
Andrew Campomizzi, BECO's Research Scientist, stops in his tracks as we detect the first eastern meadowlark of the morning.
Photo: Xuan Zhang
Eastern meadowlark adult and young
An adult eastern meadowlark (on the left) next to one of its recently fledged young.
Photo: Xuan Zhang
Xuan Zhang photographing eastern meadowlarks
Xuan Zhang, BECO Field Biologist, waits patiently for an opportunity to capture the image above.
Photo: Andrew Campomizzi
Now that the grassland birds are finished nesting, we'll begin entering, organizing, and analyzing the data we collected this year. Overall, these data will help improve our understanding of the impacts of rotational grazing on nesting grassland birds and provide inspiration for possible conservation strategies to support grassland birds in pastures. Although we had not planned to study eastern meadowlarks and Savannah sparrows this summer, the opportunity to do so has provided us with new insights to apply to our future grassland bird research.
Coyote and sunrise at the community pasture
A coyote trots by as the rising sun burns off the morning fog blanketing the pasture.
Photo: Zoé Lebrun-Southcott
Funding for BECO's 2020 grassland bird research at the Grey-Dufferin Community Pasture was provided by the Government of Ontario, the Helen McCrea Peacock Foundation, The McLean Foundation, and our generous donors.
www.beco-birds.org www.beco-birds.org
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