Kestrel Boxes Provide Homes For Pint-Sized Predators

Jun 6, 2016

A once common falcon is getting a boost from local researchers who are hoping to rebuild its numbers.

In this week’s Exploradio, WKSU’s Jeff St.Clair looks at efforts to improve living conditions for the tiny, but mighty kestrel.

Not a chicken hawk, or a sparrow hawk...
Growing up, I learned a lot about the natural world through cartoons.

Admittedly, all weren’t 100 percent accurate, especially when it came to learning ornithology. Take, for example, the Looney Tunes chicken hawk character, Henery Hawk.

Henery Hawk says he's a chicken hawk, but he may really be a sparrow hawk. Both names have fallen out of favor with birders.
Credit LOONEY TUNES

“I’m a rootin’ toot’in Chicken Hawk," says Henery, to which Foghorn Leghorn replies, "You’re too teeny to catch chickens.”

Too small to catch chickens; that pint-sized predator might be a sparrow hawk.

Now I find even that name isn’t right.   

A fierce miniature falcon
Kestrels, according to Hiram College conservation biology professor Sarah Mabey, don't eat sparrows.

But they do eat farm pests like mice and grasshoppers.

I'm with Mabey at the school’s field station hoping to spot a kestrel. She says they, along with other grassland species "are experiencing declines across North America.”

The kestrel is a fierce, miniature falcon whose numbers in Northeast Ohio have fallen by 63 percent since the 1960’s.

About the size of a robin, but with a sleek, raptor profile, kestrels were once a common sight, perched on phone lines along country roads across Ohio.

A nest box invader
But Mabey says a loss of habitat is one reason we’re seeing fewer of them.

“We have development – urbanization, suburbanization. We have more tall structures in our habitats."

Hiram field station director Jim Metzinger shows me another reason kestrels are struggling.

We approach a wooden nesting box sitting atop a 20-foot pole at the edge of a field. 

Metzinger and his students installed it last fall to attract a pair of kestrels –  but some other bird has taken up residence. It beats a hasty exit - too quickly for us to identify, but we can check its nest.

The American kestrel is a beautiful miniature falcon whose numbers have fallen dramatically in recent decades due to habitat loss and competition for nesting sites with invasive starlings.
Credit JON NELSON / CC FLICKR

Normally to peer into this nest box we’d need a very tall ladder, but this box is rigged with a pulley that Metzinger cranks to bring it down.

One of his students designed the pulley system to allow easy access for annual cleaning and to check on the occupants, in this case a set of beautiful blue eggs - starling eggs. 

A clutch of starling eggs was found in the kestrel nesting box at Hiram College Field Station.
Credit JEFF ST.CLAIR / WKSU

"The European starling is an invasive species which is probably the reason behind the decline of American kestrels in this part of Ohio," says Metzinger.

There won’t be any kestrels hatched here this year. 

Suddenly, on the other side of a large field, Metzinger spots a pair of kestrels sitting on a wire.

He guesses they’re nesting in a nearby barn. He hopes their chicks next year will beat the starlings to the nest box.

Next boxes in the community
Metzinger has teamed with a local school district to help spread the word about kestrels.

Eddie Judd teaches pre-engineering at Crestwood Middle School and right away his students tackled the kestrel question by improving the pulley system used to raise and lower the nest boxes.

A kestrel nesting box at Hiram College Field Station can be raised and lowered using a student-designed pulley system.
Credit JEFF ST.CLAIR / WKSU

They added PVC rollers to smooth the slide up and down the pole, and modified the latch system.

Judd’s students also experimented with designs for kestrel boxes, built around specific parameters for overall size and the diameter of the entrance hole.

Judd says the need to build kestrel boxes was new to him, but fit with the purpose of his class "to be community minded and to find a solution to a need in the community.”

And part of that solution is a plan to install student designed nesting boxes at Crestwood school and on some of his students' family farms in Mantua.

Hope for next year
Back at the Hiram field station, researcher Sarah Mabey looks forward to finding a nesting pair of kestrels in the box so that she can learn more about their life cycles. Her goal is to band the adults with tiny radio frequency tags that can be monitored by an antenna mounted on the box.

“Then we can register when the mother comes and when the dad comes, and how frequently they visit and how long they stay,” says Mabey.

Mabey says other regions that have experimented with kestrel boxes have seen populations double. She says it’s the first step in bringing back this beautiful pint-sized predatory bird.