SOUTH BEND — Known as the fastest moving creature on Earth, the peregrine falcon carries this title for good reason. Falcon parents will do nearly anything to protect their young, swooping from cliffs or rooftops, at high speeds of up to more than 200 miles per hour, to attack anyone who threatens the nest.

Since 2003, a pair of peregrines, Zephyr and Guinevere, annually build a nest and give birth to a brood of young falcons on the rooftop of South Bend’s County-City Building. Tuesday, conservation officers from Indiana’s Department of Natural Resources and Department of Fish and Wildlife journeyed to the building to attach color bands to the legs of the newest brood of 3-week-old chicks.

However, by Tuesday morning, the family of peregrines had lost one of its youngest. Over the weekend, the male chick was blown away from the nest, presumably by a strong gust of wind and unable to fly yet, fell tragically to the roof of the fifth floor of the building.

“He got inadvertently dumped down onto the fifth floor roof sometime over the weekend,” said Carol Riewe, a local naturalist who frequently monitors the falcons via webcam.

“We have two that are healthy at this point. The problem will arise when they fledge the nest, when they’re new flyers and they’re not doing very well yet. It takes them a couple of weeks to become comfortable with how to work the wind currents (and) how to land.”

The conservation officers gathered the two remaining chicks from the roof Tuesday at 11 a.m. to band their legs. This banding occurs annually to protect and monitor the birds because of their low population numbers and status as an endangered species in Indiana.

“When you band a bird, whenever that bird shows up someplace and somebody gets the band number, then it tells you where these birds are moving, the pathways,” said Riewe. “When (biologists) put band numbers together over the course of years, it tells (them) whether the population is declining or increasing, and (they) monitor the numbers that way.”

Since the Indiana officers began banding Zephyr and Guinevere’s broods back in 2003, several of the young falcons have moved to different areas. A female from the 2007 nest flew out to Racine, Wis., where she settled with a mate in 2010. A male made a nest in Michigan City at the Northern Indiana Public Service Company power plant, while still another put down roots in the Kalamazoo area.

“The word ‘peregrine’ means ‘wanderer,’” said Riewe, “and that’s what they do. You don’t always find out (where they travel) because the bird has to show up someplace where somebody’s watching and where someone has optics to get a band number.”

Zephyr and Guinevere themselves have remained nested atop the County-City Building year round since 2003.

“This pair doesn’t go anywhere,” said Riewe. “They just arrived. The male had been hacked in Iowa, clipped in Mississippi. The female, we don’t know where she came from. She wasn’t banded, so we have no way of knowing her ancestors. We just banded her the first year when we banded the first year chicks, so we don’t know where. She’s a wild card.”

Zephyr lost his leg last spring, an injury that is still largely a mystery to local naturalists but speculated to be caused by an illegal leg hold trap. Many predicted he would die or fail in his duties as the family hunter following the injury, but he and his family appear to be thriving, except for the recent loss of one of the chicks.

“We can only guess fairly well without actually having the bird in hand to see how thin he is or isn’t,” said Riewe, “and to see what that foot looks like. We have to just guess that, so far, he’s making it work.”

As for the chicks’ banding process, two different sizes of leg bands are usually needed for females and males, since in any species of birds of prey, including hawks, owls, falcons and eagles, females are larger than males. However, both chicks banded Tuesday were females. At the age of 25 or 26 days, the chicks’ sex could be determined accurately.

In addition to banding the young peregrines Tuesday,the conservation officers took their blood samples, which not only allows them to monitor the birds’ health but also ensures that they have the falcons’ DNA on record.

“They look for DNA, because you know, who knows where the antecedents of these birds are,” said Riewe, “and so, they keep DNA samples and there’s a national database, so if you find one of these birds, you can plug that band number in there and you can get information on that bird.”

Riewe said that if anything, more volunteers are needed to watch the peregrines sufficiently over the next few weeks as the chicks prepare to fledge the nest.

“If people would like to come down, especially the first couple of weeks that these birds are new flyers,” she said, “and just hang around down here. Sit on a bench and watch. Keep an eye on them, so that when the bird flies from point A to point B, we know where point B is.

“We put posters out in some of these buildings down here and (they have) several phone numbers of people who are watchers. If someone finds a bird down, they can call of those numbers and get one of us to come down and pick the bird up.”