Grassland Birds

Vermont’s grasslands – the acreage where grasses, sedges and wildflowers dominate the landscape, with little or no intrusion from shade trees and shrubs – have waxed and waned since European colonists arrived. And so have the populations of birds that depend on this kind of habitat. Nowadays, they are in decline.

We don’t know precisely how much grassland existed in Vermont before the colonial era, although it’s well established that old growth forests dominated the landscape. By the turn of the 20th century, though, 70 percent of Vermont’s forests had been cleared for crops and grazing. That opened up fresh territory for birds like the Bobolink and Savannah Sparrow, both of which we still find in Norwich, as well as the Eastern Meadowlark, Upland Sandpiper, Grasshopper Sparrow and Vesper Sparrow. Kestrels, Northern Harriers, song sparrows and red-wing blackbirds also frequent grasslands, though these birds are not entirely dependent on sunny meadows.

In the past hundred years, the situation has reversed. Now, about three quarters of Vermont is forested, and many of the birds dependent on grassland are in serious decline, or on the threatened and endangered species list according to the Vermont Grassland Bird Management and Recovery Plan. And when our use of the land shifts these days, the changes may further squeeze the open spaces most friendly to these species of birds. This may happen whether abandoned pasture reverts to woodlands, or forests fall to expanding human settlements.

Here in Norwich and throughout New England, the Vermont Center for Ecostudies has mapped grasslands suitable for these birds, and engaged landowners and farmers through their New England Grassland Ambassadors program to help preserve high-quality grassland habitat.

Elena Mihaly, owner of Cossingham Farm, has enrolled her farm in the New England Grassland Ambassador program to protect the Bobolinks that nest there. The farm’s pasture is leased to a grower of grass-fed beef, but the cattle are not allowed onto the pasture until after the baby birds have fledged. Other Grassland Ambassadors in Norwich have delayed hay mowing with observed increases in Bobolinks, sparrows, red-wing blackbirds and many varieties of dragonflies. It is challenging, however, as nesting times can vary greatly from year to year depending on weather conditions.

But that’s the exception to the statewide situation. Most grassland in Vermont these days occurs either on intensively farmed agricultural fields, or at commercial campuses, airports, military installations and the like.

Heavy use of chemical fertilizers, pesticides and herbicides has fueled a shift toward larger, more intensive, single-crop farms. Consequently, many farmers are converting hayfields to row crops, while those remaining are typically mowed earlier and more frequently. As grassland birds are ground nesters, this causes high mortality and nest failure. Research has shown that when mowing and grazing schedules accommodate the bird’s nesting periods, birth rates and survival rates increase signifi- cantly. Decreasing or, even better, eliminating pesticides and herbicides helps as well.

Intensive grazing practices and the increasing preference for cattle over sheep have also increased nest failure. Cattle trample the birds and nests.

Fragmentation of fields and sprawling commercial and residential development also take their toll. Some birds will not make nests close to field edges. Bobolinks and Savannah Sparrows, for example, are very sensitive to the presence of trees and development in the areas surrounding the fields.

Reforestation has eliminated much of the grassland in Vermont that existed in the nineteenth century. State conservation goals for grasslands conflict with goals to restore the kind of forests that historically covered much of the Champlain Valley, the Clayplain Forest.

The Clayplain Forest grew on deep, fertile, clay soil. Research has shown that these were oak dominant forests with many species that were uncommon in other areas of Vermont. White Oak, for example, was prevalent. Indeed, on one of the two remaining parcels of original Clayplain Forest, there is a White Oak that dates to the 1640s.

It’s challenging to preserve grassland at airports and on military campuses. Mowing schedules at airports, dictated by the Federal Aviation Administration, often conflict with the needs of grassland birds. Planning at these facilities often fails to take grassland conservation into account.