A female kestrel is swooping and diving above a nest box that contains her young. Her goal is to scare away the humans intruding into her personal space and home.

Unsuccessful, she gets her mate, and then there are two birds swooping and diving, threatening to harm Mike Shaw with their sharp claws and beaks as he extracts their chicks from the nest.

This time of year, kestrels have chicks that are becoming fledglings ready to leave their nests. Before they take flight, Shaw marks each kestrel with a leg band, and each of the birds is weighed and measured.

“Everyone thinks that they are common, but their numbers are going down sharply,” Shaw says. “In the last few years, their numbers have gone down almost 50 percent. In the last 10 years, the spike in the decline has been very sharp and it’s persistent and no one knows why.”

Shaw climbs down the ladder unscathed by the parent kestrels. He has the chicks — two males and a female — and then begins to work with other volunteers in the dry, protected area of Karen Olson’s garage in Herriman.

“This one looks super cute,” Shaw says as he measures the chick. The chick weighs in at just 113 grams.

HawkWatch International started an American Kestrel Nest Box Program for an American Kestrel Study project in 2013, and 10 of those nest boxes were installed in northern Utah County earlier this spring to reestablish the raptor’s numbers in its native habitat.

“We hope to see active boxes next year,” said Joseph Dane, development director for Hawk Watch. “They were installed late in the season to attract kestrels this year.”

The American kestrel, often called the sparrow-hawk, is a raptor sharply declining in numbers throughout North America and has caught the attention of falconers associations and Hawk Watch International.

“That is why all these raptor biologists are doing this study and trying to pool our data,” Shaw said. “We’d like to look down in Utah County a little bit, but we can’t do that without the help of citizens in the county.

“It’s so important for us to have volunteers because we can’t have eyes on every single nest box.”

Those interested in helping in a volunteer capacity can go online to learn more about the program at hawkwatch.org.

Olson got interested in helping Hawk Watch about two years ago. She currently has two nest boxes in her backyard and keeps an eye on the kestrels.

“I really get a blow-by-blow play of how kestrels maneuver, fly, bring in prey for the babies,” Olson said.

Kestrels nested in the box closest to Olson’s house. The female kestrel laid five eggs; not all survived.

“We have three chicks that we are going to study,” Olsen said. “We are going to measure them and weigh them and see if they are healthy and then we are going to band them.”

The bands will tell the volunteers where the chick came from the prior year. Olsen said she is fortunate to have an active nest box for the American kestrel.

“One of the projects for Hawk Watch is to study the American kestrel because their numbers are declining and we are trying to understand what’s going on with the population and trying to promote healthy nesting,” Olson said.

The kestrel’s range includes most of North America, where it is often seen perched on telephone poles, power lines and in city parks. The cavity nesters seek out natural tree cavities, river banks, old buildings and man-made nest boxes.

“The kestrel’s natural nest sites are becoming increasingly rare and they need our help,” Dane said. “We are getting volunteers involved in a citizen science capacity to help collect data and try and find the reasons why kestrel numbers have been declining.”