Can small pasture management changes help grassland birds?

The bobolink and other declining avian grassland species have received assistance from farmers and conservation researchers in Grey County. 

Through a $62,500 grant from the Ontario Trillium Foundation, Bird Ecology and Conservation Ontario (BECO) – a non-profit conservation organization – has been working with landowners to identify nest locations and bird population numbers in the county’s pasture lands and hayfields. 

Why it matters: When in Canada, grassland birds like the bobolink predominantly nest in agricultural landscapes. Improving habitat here could offset other habitat challenges elsewhere. 

The idea is to raise awareness of how many birds are nesting in the province’s agricultural landscape, while developing strategies to reduce nest disturbance and fit within the production methods of each farm. 

The bobolink relies on grassland for nesting, mostly in hayfields and pastures. Because of overlap between the nesting season and the time when farmers cut hay and graze pastures, nests are vulnerable to inadvertent destruction. 

“It really depends on the grazing intensity but the nests can be trampled or exposed to predators,” says Zoe Lebrun-Southcott, executive director of BECO. The same issues apply to hay harvesting. 

Conservation strategies generally include recommendations to delaying grazing or hay cutting until mid-July. This does not fit well with the agricultural calendar, making it difficult for farmers to act. 

In addition to cataloging populations, Lebrun-Southcott and her colleagues worked with more than 12 farms in and around Grey County this summer to discover whether smaller, more practical production changes could make a difference. Lighter early season grazing and simply avoiding nesting areas were among the strategies. 

“We time it so the [initial] grazing occurs after the bobolink has arrived, but early enough that if the nests fail, they can renest… We don’t want the birds to abandon the pastures,” says Lebrun-Southcott. Moving livestock onto different pastures more quickly helped ensure nests were not overly exposed. 

The strategies worked well on some farms and less so on others. Production realities and the physical characteristics of each farm determined the level of conservation success. 

As described in a newsletter from BECO in July, finding ways to leave some pastures or hayfields undisturbed during the nesting season can be a challenge for farmers because animals need to graze and hay needs to be cut to provide forage for winter. 

Analyses of the data collected this year has broadened understanding of how 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,” says Lebrun-Southcott.

Grassland bird species including the bobolink are still a common sight across the province. But according to LeBrun-Southcott, this perception hides a steep decline in population – a 75 per cent drop between 1970 and 2019, including a 37 per cent drop between 2009 and 2019 alone. 

“In terms of the number of bobolinks in Ontario, the recovery strategy for the bobolink and eastern meadowlark in Ontario estimated that in 2010 there were roughly 570,000 adult bobolinks, or about 285,000 breeding pairs. In 2015, the Bobolink and Eastern Meadowlark Government Response Statement estimated that the bobolink population in Ontario was roughly 465,000 adult birds,” says Lebrun-Southcott.

Population declines in bobolinks, one of the main species of concern for much of the BECO project, are largely due to changes in farming practices and production styles.