- Written by Clyde McMillan-Gamber Clyde McMillan-Gamber
Wintering flocks of horned larks, house sparrows, starlings, rock pigeons, mourning doves, and other species of birds are adapted to eating grass, weed seeds, and bits of corn in extensive fields in southeastern Pennsylvania during winter.
These same birds also pick chewed, but undigested, bits of corn from livestock manure spread on top of snow when other foods are buried by snow.
Field mice aren’t abundant in those fields because of annual plowing, discing, and harvesting. But mice are common along roadside shoulders and banks in cropland. There they feed, make nests, and raise young among roots of tall grasses and weeds.
At least six kinds of hawks wintering in southeastern Pennsylvania—including American kestrels, merlins, peregrines, Cooper’s hawks, red-tailed hawks, and northern harriers—prey on mice and birds in open farmland. Kestrels, peregrines, Cooper’s, and red-tails nest locally, and all these diurnal raptors make croplands more interesting in winter.
Kestrels, merlins, and peregrines are all fast-flying falcons that perch on roadside poles to watch for prey. They all have tapered, swept-back wings for swift flight. Smallest of the falcons, kestrels are about the size of blue jays. They hover into the wind as they watch for mice along grassy roadsides.
Merlins are darker and a bit bigger than kestrels. They catch small birds, such as horned larks and various sparrow species, by ambush and their speedy flight low to the ground in open country, including agricultural areas.
The crow-sized peregrines mostly snare rock pigeons, mourning doves, and starlings in midair over open country. Peregrines dive through the air at 180 miles per hour and hit their victims with their chests.
The birds are stunned or killed and drop to the ground.
Peregrines swing around in the air, grab their victims in their claws in midair, and fly to a perch to consume their catch. Peregrines and merlins reduce competition for food between them by catching different-sized prey.
Cooper’s hawks traditionally are forest dwellers that prey on birds. But some Cooper’s have adapted to catching birds in farm country, perhaps giving peregrines competition. Cooper’s are swift flyers, able to chase down their feathered victims.
Red-tailed hawks soar over farmland to watch for mice and other rodents. When prey is spotted, they dive swiftly to snare it.
Northern harriers flap and soar slowly into the wind close to the ground in farmland to watch and listen for mice and small birds. When victims are spotted, they abruptly drop to the ground to snare them in their claws.
Hawks wintering in farmland prey mostly on mice and birds, doing so in different ways. And they make local fields more interesting in winter.
Clyde McMillan-Gamber is a retired Lancaster County Parks naturalist.