It’s not a great time to be a grassland bird. Their numbers are diving faster than a hawk after a ground squirrel.
Yesterday I learned more precisely how grassland birds are doing in my neighborhood (Southwestern Wisconsin). Mike Guzy did his Wildlife Ecology Ph.D. research just a few miles from my land, and he shared his results at the UW Arboretum winter lecture series.
From a bird’s eye view, all grasslands are not created equal. Some birds, like kildeer and grasshopper sparrow, like low grass with some bare ground. Then there are the sedge wrens and Henslow’s sparrows who thrive in really tall grasses.
My prairie restoration seems to be reasserting itself in the medium height grasses, which are preferred by upland sandpipers, savanna sparrows, meadowlark and bobolink.
Not unlike the bluebird (see my post Thinking Like a Bluebird) these feathered friends have taken a heavy hit since the 1950s as farming practices have changed. At one point, farming made room for birds. Cows were pastured in meadows. Grassy areas along fence rows were part of the landscape. “Weeds” that often had food value to birds were part of cropped fields.
Fast forward to the present. We all know what’s out there now – corn and soybeans right up to the road.
But this part of Southwestern Wisconsin actually has a fair amount of land that still looks inviting to grassland birds. Guzy’s research asked what happens to birds who accept that invitation. Listening to his report, I realize how hard it is to find out.
Nesting on the ground puts grassland birds at the mercy of every other animal out there.
“Anything that comes on a free meal will eat it,” Guzy noted, adding that the protein, fat and calcium packaged in a defenseless egg is irresistible to ground squirrels, coyotes, skunks, badgers, voles, weasels, raccoons, raptors, opossums, dogs, snakes, deer and even cows.
Grassland birds must hide their nests in plain sight. They are good at it. To study them, groups of researchers (mostly undergrad science majors) must feel their way slowly, wading through an expanse of grassland in long lines walking an arm’s width apart and peering into the thick grass at their feet. When they scare up a bird, they focus on the spot where the bird appeared, but these birds will often run through the grass before taking flight to avoid giving their nesting site away.
To relax, the researchers probably looked for needles in haystacks.
Guzy narrowed his study down to meadowlarks because there were enough of them to count, and they are large enough to carry a useful radio transmitter. A bird can’t handle a transmitter that is more than 3% of its body weight, and the battery technology available makes the tiny birds like grasshopper sparrows almost impossible to track. (They can only carry a battery large enough to power the transmitter for three weeks.)
Through trial and error, Guzy learned the best way to trap, and band, and attach transmitters to meadowlarks was to set up long swaths of mist nets.
He aimed tiny video cameras at a few of the nests (those cameras aren’t cheap). With combinations of colored bands making it possible to I.D. individual birds by sight, cameras monitoring their nests and transmitters tracking their movements, Guzy gathered information about the grassland birds just a few miles from my land.
The results were not pretty. The videos showed critter after critter dining on meadowlark omelets. Nesting success was about 16.6 percent. (How would you like to start a family with those odds?) None of the birds Guzy and this team so painstakingly banded were sited the following year.
Guzy says that his research created more questions than answers, but one thing stands out loud and clear. Grassland birds need help. “We need more research to understand how birds view their landscape,” he said.
I agree. I realize that humans are not going to inconvenience themselves very much just to save a few (fewer and fewer each year) grassland birds. So we need to understand what these vanishing grassland birds absolutely need to survive, and then hopefully we can fit it in to our profit and loss statement.
Categories: Ecosystem Restoration