Raptors Excite Bartel Birders

In late December and early January, bird lovers arrived in droves at Bartel Grasslands Land and Water Reserve in southern Cook County to watch remarkably high numbers of short-eared owls, northern harriers, and rough-legged hawks.

"It was such an exciting event for the short-eared owls to return to this site where they hadn't been for 30 years," said Marianne Hahn, former president of Thorn Creek Audubon Society. This group has contributed to recent restoration efforts, which may have helped bring the birds back to Bartel.

Local birders' email listservs lit up with ecstatic accounts of the overwintering raptors. As the word got out, crowds of as many as 20 people gathered at dusk to witness the birds' aerial stunts. While an exact count is difficult since these birds hunt low to the ground, some birders reported seeing as many as six short-eared owls simultaneously. "I had never seen that many at one time," Hahn commented.

John Elliott, education manager for the Forest Preserve District of Cook County and coordinator for restoration work at Bartel, visited the reserve on a cold, blustery day during the first week of January. He watched a short-eared owl's pursuit of a northern harrier from so close up that he could see the detailed markings in the owl's plumage. "It was really a treat for me," said Elliott, who has been birding in the area for nearly three decades. The different species chased each other through the skies as they vied for hunting territory. Their prey was Bartel's exploding population of voles, also called meadow mice.

Bartel had been selected for restoration in the mid-1990s because of its potential to become a large, wide-open area attractive to many grassland birds. Fencerow trees were cut down, reducing the habitat of some vole predators and probably paving the way for their population explosion. This also created large open spaces, something that birds such as the finicky short-eared owl require. In addition, drainage tiles have been disabled, making for wetter ground, which attracts wet-grassland birds including the short-eared owl and the northern harrier.

In late fall, a group of restoration workers at Bartel were reportedly caught in the middle of a predator-prey battle in progress. Workers who had been doing controlled burns found themselves being harassed from above by northern harriers. The stewards eventually realized that because of the fires, voles were scampering across the open ground looking for cover. The workers had simply gotten in the way of the harriers' meal.

"We're cautiously saying that this is a sign of success for the restoration project," Elliott said. In order to ensure continued success, visitors to the reserve should remain on the perimeters of the grasslands. Birders predict that this raptor show probably will not be repeated as dramatically next winter at Bartel. Because of this past winter's predation, next winter's vole population is likely to be much smaller.

— Ben LeFort