Help arrives for American kestrels

If you told me the American kestrel was your favorite bird, I'd say you've made a fine choice.

The kestrel, the smallest member of the falcon family, is an easy bird to like. For starters, just look at the way it's decorated. The male, in particular, has it all going on: spots, bars, stripes and a rich color combination of rufous, white and slate blue. This bird went to the feather store and said "Give me the works."

Another reason to like kestrels, and to pull for them, is their underdog status. The species is not endangered, but kestrel numbers are steadily declining in areas such as northeast Illinois, where quality grassland habitat is shrinking. Survey data indicate annual population declines of around 10 percent. The Bird Conservation Network lists American kestrel among its Chicago Wilderness Region "Birds of Concern."

Habitat scarcity isn't the only issue. Kestrels depend upon pre-existing cavities for nesting, such as old woodpecker holes. As Eastern bluebirds and redheaded woodpeckers know all too well, such home sites are often usurped by European starlings, a relentless nonnative competitor.

Fortunately, kestrels respond to well-placed nest boxes. With that in mind, the Forest Preserve District of DuPage County initiated a kestrel nest box program this spring aimed at boosting the local kestrel population in select preserves. Seven all-cedar, pole-mounted boxes were installed by the district last month.

"I looked at sites featuring large, open, short-structured grasslands with some perching trees nearby," said Brian Kraskiewicz, district ecologist and kestrel box project leader.

Preserves where kestrels have been seen in recent years received priority. That includes Springbrook Prairie in Naperville, which received two nest boxes. Blackwell (Warrenville), Danada (Wheaton) and Greene Valley (Naperville) are among the other chosen sites.

Raptors require larger territories, so the distance between boxes must be at least a half mile.

Another limiting factor, Kraskiewicz said, is the presence of bluebirds. Kestrels and bluebirds prefer the same open habitat and if their nest boxes are too close together it raises the possibility of bluebirds becoming falcon food.

The district formalized a successful bluebird nest box program in 2000.

Kestrels will indeed prey upon birds, but their usual diet is large insects and small mammals. When I met Kraskiewicz he was installing the kestrel box at Blackwell, adjacent the preserve's native plant nursery. The district is hoping a kestrel pair will take up residence and help control the voles and mice that damage the nursery stock.

The box at Blackwell is not visible to the public but others are. Observers are urged to keep their distance and give the kestrels space if nesting occurs.

And "if" is the key word. Kraskiewicz said he hopes at least one box is occupied by kestrels this season but knows it might take a year or more to claim success.

Plenty of science-based protocol guides the construction, placement and monitoring of nest boxes, but getting a kestrel pair to move in and raise a family is still hit or miss.

Fermilab in Batavia offers a strong measure of hope. Through Fermilab Natural Areas, a volunteer organization, the site ramped up its kestrel nest box program in 2012, adding 10 additional houses. The site now maintains and monitors 12 boxes. Five of them were successful in 2015, according to Ryan Campbell, Fermi's ecologist.

The Forest Preserve District of Kane County has about 30 kestrel nest boxes in the field. Occupancy was just 8 percent in 2015 but the district remains optimistic. It checked with Audubon chapters around the Midwest with similar programs and learned that kestrel box programs often have low success in the first few years, followed by dramatic improvement once a few boxes become occupied.

Back in DuPage, Kraskiewicz plans to be patient, and he's leaving the door open for growth. He thinks the nest box program would lend itself nicely to Eagle Scout projects, and the DuPage Birding Club is a potential partner as well.

Those wishing to see an American kestrel this spring or summer have options. Best bets are Springbrook Prairie, Greene Valley (near the landfill) and Fermi. The farmlands of Kane County also are worth checking. Watch for a bird the same size and shape of a mourning dove on utility lines and other elevated perches. Kestrels do a lot of sitting and tail-bobbing as they watch for prey in the grass below.

Kestrels are aerial hunters, too. I've seen them hang in the air on flapping wings, 25 feet up, waiting for just the right moment to drop down on prey. This hovering technique is unique among falcons. Kingfishers also do it.

Once, in 2007, a kestrel perched at the top of a tree two houses down from mine. It stayed for several minutes, pumping its tail and thinking about where to go next.

That neighborhood kestrel was quite a surprise. I was thrilled! At the time, however, I was barely aware of the species' declining local population. It's encouraging to see steps being taken in and around DuPage County to conserve and raise awareness of this small and beautiful raptor.

• Jeff Reiter's column appears monthly in the Daily Herald. You can reach him via his blog, Words on Birds.blogspot.com.