NORMAL - Freshman Lauren Young was studying in a lounge near the top of Watterson Towers on the Illinois State University campus when she snapped a picture of a bird perched outside.

She knew her dad had recently become a birdwatcher, and she wanted him to see it. He thought it was a red-tail hawk.

"I just thought it would be cool if everyone saw it," Young said Wednesday.

The special education major luckily still had the camera in her purse, where she left it after taking pictures at a sorority barbecue cookoff.

The bird later was correctly identified as an adult peregrine falcon, and the picture excited Angelo Capparella, an ISU biology professor and ornithologist, and Given Harper, a raptor expert and chairman of the biology department at Illinois Wesleyan University.

The men were instrumental in gaining ISU's cooperation to erect a peregrine breeding box on top of Watterson Towers in 2006. The action was taken after a pair of the falcons and a solo falcon spent time there earlier that year.

Experts say birds may take several years before finding a breeding box and putting it to use.

"We had sort of given up this year for breeding," said Capparella, curator of ISU's John Wesley Powell/Dale Birkenholz Natural History Collection.

Harper saw a peregrine flying over the Twin Cities within the past few days. Before that, he spotted a single peregrine on Christmas Eve, another on Jan. 20 on Watterson Towers, another on Feb. 5 on Watterson Towers and another feeding on a pigeon on Feb. 23 on ISU's Manchester Hall.

Female peregrines are the larger of the two sexes, and Harper judged the latest visitor is a female.

"We still could potentially attract a pair," Harper said. "That is so neat."

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 wingspan of 43 inches.

They are the fastest birds on earth, achieving speeds of 200 mph when diving to attack their prey, which are mostly other birds.

The species became endangered after the insecticide DDT invaded the food chain and caused a loss of calcium in eggshells.

The species has rebounded, thanks to a ban on the agricultural chemical and other recovery efforts, including reintroducing them in major cities. Peregrines are naturally cliff dwellers, but they have adapted to use cliff-like skyscrapers like Watterson.

The birds generally mate in March. Eggs are hatched a month later.

The bird that dropped by ISU merely may be pausing on its way north. But there's a chance she could wait a few days to see if a male comes along.

"The word 'peregrine' means 'to wander,' and birds without territories are still moving around," Harper said. "Chicago birds are on eggs. But you never know."