Buying Time

Buying Time

For bobolinks, savannah sparrows, and other birds that make their nests in hayfields, a delayed harvest can spell the difference between life and death. 

By Les Line
Published: November-December 2009

Spring for me isn't complete without a bobolink fix or two. Simply put, I'm addicted to these harpists of the hayfields. That's why I'm parked on a grassy farm lane in the Taconic Hills of eastern New York, where I live, on a picture-perfect day in early June. The car's windows and moon roof are open to music bubbling down from an azure sky as three or four male bobolinks swagger overhead and an occasional female flutters up from her hidden nest to check out the commotion. But my immediate attention is focused on a close-by male in smart, skunklike breeding plumage, offset by a prominent straw-colored nape. The handsomest bird in the neighborhood by far, he's clinging for the moment to a wobbly dock weed, lord of a small piece of this flowing meadow of grasses and forbs.

It's a challenge to describe the bobolink's song, a flood of notes that rises higher in pitch as the vocalist hovers over his territory or emotes from a fence or shrubby tree. Besides, who could improve on the eloquence of the great Massachusetts birdman Arthur Cleveland Bent (1866-1954). "It is unique among bird songs," Bent wrote in his monumental Life Histories of North American Birds, "a bubbling delirium of ecstatic music that flows from the gifted throat of the bird like sparkling champagne." "Bobolink," of course, is an imitation of that song, as is "meadow-wink," prettiest of the bird's various folk names. Frankly, I'm surprised that the dour taxonomists who rule on avian nomenclature--and tried to get rid of the Baltimore oriole--never changed it to something more typically banal, like "buff-necked blackbird."

Sadly, the prospect of a spring without a chorus of bobolinks is very real in many places across the bird's extensive breeding range, which spans the northern United States and southern Canada. The species is by no means endangered. Partners in Flight has estimated the continental population at 11 million, including 1.5 million in North Dakota, where the bobolink is doing very well indeed on more than 3 million acres of grasslands enrolled in the U.S. Department of Agriculture's Conservation Reserve Program. But over the past 40 years bobolink numbers have declined dramatically across the eastern region of the Breeding Bird Survey, from Wisconsin and Illinois to New England and Canada's Maritime Provinces.

That's certainly true in Vermont, where the population has plummeted 75 percent, to just 100,000 birds, since the late 1960s--and is currently declining at a rate of 3.1 percent a year. The fact is, Vermont bobolinks have suffered a double whammy: the widespread loss of their adopted hay-meadow habitat to development and reforestation coupled with intensive modern agricultural practices that make it next to impossible for the birds to complete a successful nesting season.

If there's a way to slow the species' decline in the Green Mountain State, it may lie in buying time for bobolinks. Literally. And the Natural Resources Conservation Service, part of the USDA, is doing just that in collaboration with University of Vermont biologists Allan Strong and Noah Perlut. The researchers, both grassland bird specialists, have focused on developing management practices that balance the needs of birds that depend on agricultural lands for breeding and the farmers who count on those lands for their livelihood. As a result, the NRCS launched a promising new program in 2007 that offers farmers a financial incentive to delay mowing during a window of time when their hayfields could produce a healthy crop of the bobolinks and savannah sparrows that share these cultivated grasslands along with, on some fields, eastern meadowlarks and grasshopper sparrows. This past summer 10 fields on eight farms, a total of about 285 acres, were managed for the birds.

David Charron, who raises Black Angus and grows 250 acres of hay for sale in Rutland County, is one of those farmers. When asked why he signed up for the NRCS program, called New Incentives for Grassland Bird Conservation, he replied, "Bobolinks had all but disappeared around here for a time, and I enjoy having them around. If giving up one cutting of 30 acres of hay will help the birds recover, that's great."

"It certainly is," said Jim Shallow, Audubon Vermont's conservation and policy director. "Private-land stewardship is the key to healthy bird populations in New England [see a "A Tale of Two Habitats," July-August 2008]. A cost-share program that enables farmers to grow the hay they need and provide for bobolinks is a win-win."

 

When discussing bobolinks in New England, it is important to remember two things. Hayfields attracted large numbers of meadow- winks to this storied region in the first place. And the birds need a whole lot of time to launch a new generation.

Bobolinks were essentially tenants of Midwest prairies before colonial settlers began clearing the Northeast forest for agriculture. However, since the early 1900s thousands of the region's farms have been abandoned and reclaimed by forests or lost to suburban sprawl. Consider this statistic: Vermont had 11,206 dairy farms in 1947 and only 1,200 in 2007. Moreover, as Strong points out, the state's remaining grasslands have become increasingly fragmented into small patches of marginal habitat with woody edges that attract nest predators.

Vermont farmers still grow hay, of course, including 227,000 acres in the Lake Champlain Valley's picturesque dairy country. However, many of those fields have become "ecological traps" (Strong's term). Meadows that once were mowed with horses in mid-summer after the young birds had fledged are now cut early and often by farmers trying to maximize their hay harvest. First nests and any attempts to re-nest are obliterated, yet bobolinks try to use those deadly fields year after year.

I know that fate awaits my favorite bobolink fields, and it would not be a pleasant thing for a bird person to witness. "There are lots of ways to die in a hayfield," Strong said. "The nests are crushed, chopped, and eventually baled and fed to cows with the rest of the forage. Predators--gulls and crows by day, mammals at night--will eat any eggs or nestlings that might survive the mowing. The saddest thing," he continued, "is seeing the adult birds hopping up and down the windrows, trying to find nestlings buried under the cut hay. The parents may hear the young birds begging for food, but they can't get to them." Indeed, bobolink nestling mortality in mowed hayfields was estimated at 94 percent in a Cornell University study, including a heavy toll of young bobolinks that had already fledged. In contrast, Strong reports that on unmowed hayfields near Lake Champlain, where predation can be high, 46 percent of bobolink nests successfully fledged young.

Bobolinks are amazing migrants. Their round-trip to and from wintering grounds on South America's pampas--a vast swath of grasslands, marshes, and rice and sorghum fields that extends from Bolivia to northern Argentina--covers some 12,000 miles. That's one of the longest songbird migrations in the Western Hemisphere. They reach New England in mid-May, when grasses, clovers, and other herbs have grown tall enough to provide them with cover. But there's no time for weary travelers to rest. The emergent hayfields soon bristle with activity, which the noted ornithologist Olin Sewall Pettingill (1907-2001), who studied bobolinks in Michigan over many summers, vividly recounted for the January 1983 issue of Audubon.

 

"The males in their striking livery of black-and-white showed up first, brimming with vitality," Pettingill related. "Each at once claimed a segment of a field by repeatedly rising and circling over it, wings down-bent and quivering, while voicing a rollicking medley of tinkles and bubbles. Then each one settled down on a plant stalk as if to pinpoint his territorial claim, and there spread his wings and lifted his buffy nape and white shoulder feathers in display.

"The females, yellowish-brown with dark streaks that simulated dead grass stems, arrived two or three days later," Pettingill continued. "There was a frenzy of sound and action, females beseeching the attention of males with buzzy calls and taking to the air with them in close pursuit. Then they would circle back and drop into the grass, where mating was consummated. In the ensuing two weeks the females built their nests--simple cups of grasses on the ground, well shaded and obscured--and laid clutches of five to six eggs." By then it was early June. The chicks, Pettingill documented, hatched in 12 or 13 days, became strong fliers by mid-July, and by the first of August both juveniles and adults had left the natal field. They would soon embark on a prolonged fall migration in which they would not reach their final destination until January. 

That's a nine-week-long breeding season when the mowing machines must somehow be kept at bay.

 

Shelburne Farms is an environmental education center on the Lake Champlain shore south of Burlington, Vermont. It is also a fabulous place to do field work, with spectacular views of New York's Adirondack Mountains across the blue waters. Once a railroad mogul's luxurious estate, Shelburne is still a working farm, with rolling hayfields that support a herd of 125 Brown Swiss cows whose milk is made into cheddar on the premises. The bobolink season was two weeks along when I met Strong and Perlut at one of those fields, where a careful search for nests was under way.

The first hay harvest on this 45-acre field, for example, would be delayed until August 1. That's a tactic widely used in grassland bird conservation efforts, and it would be perfect for Vermont's nesting bobolinks and savannah sparrows. But not so good for the state's dairy cows. As the biologists explained, hay that's cut late loses much of its crude protein content, though it can still be used for beef, horses and sheep. Few dairy farmers, they pointed out, would be willing to delay that important first cut on one of their fields to benefit grassland birds.

Strong and Perlut had a better plan that they believed would appeal to dairy farmers: harvesting the hay early, by June 2, and then waiting 65 days before the second cut. While some egg clutches would be lost in the first mowing, the birds will soon return to nest. Strong and I walked another research field, recently mowed and spread with manure, where the scientist pointed out a savannah sparrow's nest that had been crushed by the machinery. In a week or so the grass would be tall enough to provide nesting habitat, and in fact we startled a male bobolink, which burst into song, hovering over our heads like a small black helicopter. Presumably he had already staked out his territory and was waiting for one or more mates to arrive. (Bobolinks tend to be polygamous, and males may have four females under their wings at the same time.) 

The researchers closely monitored 28 nests on those two fields last summer, and 23 were successful, producing 84 young. They found little difference between late cut and early cut fields in the average number of fledglings per female. And they are optimistic about the long-term prospects of the NRCS initiative--part of the agency's Environmental Quality Incentives Program, or EQIP--which now pays farmers $135 an acre per year during a three-year contract. Participants are required to make early season cuts, followed by about nine weeks of rest, on fields that include at least 20 uninterrupted acres of grassland. The timing is based on the bobolinks' need for relatively tall grass before they nest and the long fledging period. The typical cutting cycle, Strong notes, is five to six weeks, with three or four mowings a summer.

 One of the original aims of EQIP, says Vermont NRCS biologist Toby Alexander, was to promote livestock production and environmental quality as compatible goals. "Our initial emphasis was on waste and water quality. But we also wanted to include at-risk wildlife and habitat." The Vermont incentive program is unique because the traditional approach to grassland bird conservation has been to leave fields unmowed until the breeding season is over. That's just not realistic in dairy country, he said. The money offered, however, isn't enough to fully offset a participating farmer's losses, and so a little altruism is essential. David Charron receives about $3,000 from the program, but in a good year he would get 2,500 square bales, weighing 40 pounds and worth $4 apiece, from the second cut on the 30-acre field he has dedicated to raising bobolinks. The delayed crop, he added, loses a lot of quality as feed.

Not every hayfield is eligible for EQIP funds. The NRCS is looking for those that are fairly large and somewhat square-shaped with no roads, hedgerows, streams, or edge habitat. "The ideal hayfield would be one sitting right in the middle of other grasslands," said Alexander. "We inspect every potential site and decline as many applications as we accept," he noted, adding that the NRCS's biggest struggle is reaching out to landowners. "We have the capacity to enroll a lot of fields, and we're counting on Audubon Vermont to help direct farmers to EQIP."

That's good news. Bobolinks and their sparkling music have been the essence of summer in rural New England since the time of one-room schoolhouses, where farm kids read William Cullen Bryant's poem Robert of Lincoln, a pretty good natural history lesson set to rhyme. I grew up in a small village in western Michigan with dairy barns and those little clapboard schools scattered all around, and I still remember the first stanza: 

Merrily swinging on brier and weed / Near to the nest of his little dame, / Over the mountain side or mead, / Robert of Lincoln is telling his name: / Bob-o'-link, bob-o'-link, / Spink, spank, spink; / Snug and safe in that nest of ours, / Hidden among the summer flowers. / Chee, chee, chee!"

 

The mixed news, as Allan Strong attested, is that the bobolink population in Vermont will never be what it was in the 1960s. "We simply don't have the acreage of farmland that we did 50 years ago. The hope is that we can make the present population sustainable. The results from our research with the new EQIP program are a testament to how resilient bobolinks can be in the face of intensive agriculture management. So if we can somehow ensure that bobolinks nesting in Vermont are replacing themselves, then we'll be doing okay."

But Strong isn't making any promises. "Farmers may find that they can live with the amount and quality of hay being harvested with a delayed second cut," he said, "but the question is whether they will stay with or adopt that practice without the incentive payment." And he added, "If we continue to lose farms to development and forest, we will be looking at even smaller bobolink populations. There's very little incentive to keep those lands in grass.

"The day may come," Strong continued, "when some of our best bobolink production will be in places where there are single-family homes on 10 to 20 acres of former grassland or pasture. Assuming that kind of habitat appeals to the landowners."

Of course, "Robert of Lincoln" will keep coming back to Vermont wherever hayfields beckon, piping, as Bryant penned long ago, "that merry old strain." The question, now and in the future, is whether he and his little dame will find a safe place to raise their children.

Magazine Category
Topic

Author Profile

Les Line

Type: Author | From: Audubon Magazine