NORMAL - A peregrine falcon apparently is deciding whether to adopt a new roosting box as its new home atop Watterson Towers on the Illinois State University campus.

A reported sighting of the bird at the dormitory was listed on a local birding Web site on Saturday. Raptor expert Given Harper, who leads Illinois Wesleyan University's biology department, saw an adult peregrine, probably the same one, a week ago on Normal's east side.

Though Harper lacked adequate binoculars for a close look, he thinks the bird is a male. Male birds typically arrive in an area before females, he added.

Harper thinks the bird may have been in the area since early this month.

Once listed as endangered, peregrine falcons are normally cliff dwellers in the wild, but they have adapted to nest on tall buildings in major urban centers in North America, including Chicago, St. Louis and Indianapolis, where they have been reintroduced.

According to the Cornell Laboratory of Ornithology, a peregrine falcon is a medium-sized hawk with a black mustache face marking and long, pointed wings. The birds can reach 19 inches in height with a wing span of 43 inches. They are the fastest birds on earth, diving to speeds of 200 mph when attacking their prey, which are mostly birds.

Harper, bird expert Angelo Capparella of ISU's biology department and the John Wesley Powell chapter of the National Audubon Society were instrumental in erecting a peregrine falcon roosting box on Watterson Towers in October. That action was taken after a pair of the birds used Watterson Towers as a temporary perch last spring. Several other peregrines were seen buzzing the dormitory about the same time as they migrated south for the winter. As many as three falcons were seen there in one day.

The biologists hope the addition of the box will entice a peregrine mating pair to take up residence and raise offspring. But, whether the recent arrival will stay and attract a female bird remains to be seen, they said.

"We think it's a good sign as far as this building being a major attractant," Capparella said. "But, you know how new homeowners sometimes are. Now, we just watch and wait."

"This is exciting. It shows one is at least interested," Harper said. "If they find a suitable place, they might hang out and see if it works out."

The timing suggests the most recent peregrine is a year-around North American resident rather than a member of the migrating peregrines that fly from the northern tundra to winter in South America and back again. Tundra-based peregrines wouldn't be expected to return for some time, the experts said.

Meanwhile, if the Central Illinois winter turns harsh, the peregrine wouldn't necessarily leave the Twin Cities, Harper said.

"They are hardy and there's abundant prey here," Harper said. "What they need for perching is shelter, and Watterson had that even without the box."