The Alachua Audubon Society (AAS) has worked for decades to solve a housing shortage, with members building and financing hundreds of cedar-sided, metal-roofed homes with furnishings provided and a 3-inch diameter entrance.

While small by apartment standards, these one-room homes with less than a square foot of space work well for American Kestrels.

The local kestrel population has taken to these “nest boxes” with varying consistency, and the AAS has recently shifted its plan to house what is America’s most populous falcon—but also one in decline.

Instead of peppering fields and power lines with boxes, the AAS has partnered with the Avian Research and Conservation Institute to track young kestrels and see where they stay. Then, the society can work with surrounding property owners to build nest boxes and manage land to the benefit of the kestrels.  

The society is also specifically interested in the Southeastern subspecies of the American Kestrel—the only kestrel species in the Americas.    

Ken Meyer, executive director at the institute, said the Southeastern American Kestrel has declined 82% in the past 70 years. The Florida Fish and Wildlife Conservation Commission estimates that 1,350 to 1,500 breeding pairs remain in the state.  

In Alachua County, the AAS monitors 35 kestrel boxes. Last year, roughly half of those boxes had a successful nesting couple and produced 60 to 70 baby kestrels that successfully fledged. All were the Southeastern subspecies.  

The Southeastern subspecies is identical to the rest of the American Kestrels who migrate to Florida each year. So, a kestrel spotted in December could be either, however by March, when the migrating kestrels leave, anyone remaining is in the Southeastern subspecies.  

The subspecies used to occupy seven states across the region. Florida remains the largest stronghold, and Meyer estimates Georgia has 100 to 200 breeding pairs left.  

For the kestrel species as a whole, The Peregrine Fund estimates that the population has reduced by half since the 1970s.  

“They’ve declined for so long, gradually, that people haven’t become alarmed by the fact that we’re losing them,” Meyer said. 

Despite the losses, the kestrel remains the most populous falcon in the states and remains a favorite of birders who still get plenty of sightings.  

Meyer said the bird’s popularity might contribute to its future as groups around the country research the species. Still, Meyer said he has more questions about the bird than answers. 

How much area do they need? What does their home range look like? And what’s their survival like? What are the threats, the most important threats, they face during the year? And how can AAS and others intervene to reduce those threats? 

Kestrels differ from nest-building birds. The small raptors opt for tree cavities instead. However, without beaks suitable to carving tree cavities, kestrels and other populations rely on woodpeckers and other animals to make the home. Then, the kestrel swoops in, evicting the former occupants without time to take the doormat with them. 

Of course, the kestrel itself must grab, and defend, the cavity from like-minded home buyers like screech owls, great crested flycatchers, eastern bluebirds and every type of squirrel. 

The AAS nesting boxes provide another option for the kestrels. Meyer said tree cavities have been harder to find as development occurs.  

To find the best spot for these boxes, Meyer and the AAS began tracking kestrels in 2021. The team started with radio-telemetry trackers, but the devices are tough to manage for long ranges, requiring a plane to follow from the air to get a fix.  

This year, the team transitioned to cellular trackers for the female fledgling. Meyer said the trial has been a success, and the team is still keeping tabs on the kestrels as they wing their way across North Florida.  

“What we’re finding right out of the nest box, within the first week and a half to three weeks, these birds are going long distances—males and females—40 miles, 45, 50, I think the longest was 53 miles,” Meyer said. 

Since this is the first year being able to track the kestrels so closely, the team isn’t sure where the females will end up during nesting season. If it’s back in Alachua County, they could see the birds again as they prepare to raise their own clutch of kestrels before even reaching their first birthday. Some males with the telemetry trackers have already returned to the area.  

Tracking kestrels is tougher than other birds of prey because of their size. Male kestrels weigh around 100 grams or less—about the same as a deck of playing cards. Females weigh more, ranging from 100 grams to 120 grams.  

The extreme light weight helps kestrels hover in the air during hunting, but also means trackers can only be a couple of grams to abide by national guidelines. The guidelines say the tracker can be no more than 3% of the bird’s body weight.  

Meyer and the AAS crew start the work in the spring. Eric Amundson leads the kestrel program for AAS, taking over for Bob Simmons a few years ago.  

He said the team visits the kestrel boxes in March to see which are being used. Sometimes a box will be used for several years in a row before it lies empty for a time. With a breeding pair spotted, the team will monitor the boxes for predators—mainly fire ants.  

Right before the baby birds are ready to leave the nest, the team prepares to attach trackers. They use cameras and nets on poles to get the birds, weigh them and attach trackers if the numbers work. Then, the birds go back in the box they’ve called home their whole lives.  

Soon after, the birds fly off—free from mother and father but with the team in Alachua County still watching.  

“I’ve tagged lots and lots of birds—and I still do—and I never feel great about it,” Meyer said. “I feel great about the data we might get. But it’s not a pleasant feeling to be putting something unnatural on a bird. So, we take it really seriously. We’re proud of our record, and we want folks to know that we’re not collecting this information just for fun.” 

During the rest of the year, Amundson and AAS continue the work of maintaining the now, hopefully empty nest boxes. In November, the group checked on six boxes near Watermelon Pond in Newberry.  

The boxes are located on a parcel owned by Alachua County. In two trucks, the group drives to each with eyes scanning the skies. A stop includes clearing the box contents and adding new nesting material. The team keeps the nesting material for study, finding remains of grasshoppers and lizards to examine the baby kestrel diet.  

Fire ant repellant is also spread around the site. The boxes are positioned from 10 feet to 20 feet high and each tree or power line has a strip of sheet metal around the trunk. The metal has the number/letter combination that identifies the kestrel box, and they also deter rat snakes.  

For this trip, one box has fallen to the ground. The crew has a spare and puts the new kestrel box in place. Multiple other boxes have had their entrances enlarged to accommodate a larger bird. The crew screws new wood pieces to the front to again form a 3-inch diameter. 

Sometimes, the nests still have occupants.  

“It’s kind of scary when you open the Kestrel box 20 feet up in the air, and there’s a big rat snake sitting in the box,” Amundson said.  

The data the AAS team gathers will hopefully help bring understanding to the kestrel situation. Meyer said he thinks the local information would be useful to groups across the country who also work with kestrel—just like how the AAS keeps an eye on national studies.  

“They’re all interested now in the reasons for the decline,” Meyer said. “So, reason to be hopeful, especially for such a little jewel of a bird that’s easy for the public to love. That doesn’t hurt.”