American Kestrels in Decline

A male American kestrel dines on a vole, highlighting one of their important roles, rodent control.

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Almost 20 years ago, I wrote about an experience our family had nurturing an injured American kestrel back to health. In that column I boldly proclaimed that in our area, kestrel populations were doing well, thriving really. I was totally unaware that even then, people who follow bird trends were already noticing declines in American kestrel numbers.

With that said, kestrels are still also the most numerous raptors in the Americas. That might give armchair biologists plenty of reason to state that there is no problem. Just look on any telephone line in their preferred open habitat and you would be likely to see a kestrel, they could reason.

However, a glance at the long-term trend shows that the population is following the same trajectory of the peregrine falcon—one that began in the late 1940s after the introduction of the insecticide, DDT. And we all remember how close we came to losing the peregrines in just 50 years.

Kestrels are indeed widespread. I have seen them in Alaska and British Columbia, Virginia and California, Arizona and throughout the Midwest and the Great Lakes states. If I ever get there, I may see them in Mexico, Central America and all the way down to Tierra Del Fuego at the tip of South America.

This smallest of all North American raptors (excluding several owl species) is a product of wide-open spaces and is a food generalist, eating just about anything smaller than itself including mice, ground squirrels, amphibians, reptiles, and birds. However, its preferred food is invertebrates such as large insects and spiders.

Kestrels are probably the most beautiful of raptors as well. Like other falcons, they have long tails and long pointed wings. Their coloration is astounding, with two strong black facial bars on a white face with a blue-gray crown topped with a rufous (birder speak for bright brown) cap. They have a rufous barred back and a black tipped tail. Females have rufous-barred wings, but male wings are blue-gray.

Kestrel numbers have dropped by an estimated 2 million since 1970. This data comes from several different sources such as decades of fall raptor migration monitoring, nesting box counts and even the number of birds showing up at rehabilitation centers (down by about half), all of which agree that kestrel numbers are declining.

Research is underway to try and determine the cause of the decline, but experts believe that two factors will be the likely causes. First is habitat loss. Every wild animal species on Earth is facing this dilemma as the dominant species continues to expand its footprint. With kestrels, the loss of open spaces for foraging may be key. What does a kestrel do if it migrates back to its summer home only to find that it has become a subdivision? Scientists are asking this very question and fitting kestrels with transmitters to find out.

As with the peregrine, the second likely cause is pesticides. By their nature, pesticides reduce the number of insects and rodents available to kestrels. Further, as we saw with DDT, the new neurotoxic insecticides, called neonicotinoids, are especially concerning because they are potent, widely used, and spread up the food chain. With kestrels’ focus on insects, this becomes a problem quickly.

Predation by Cooper’s hawks and European starling invasion of quality nesting cavities are two other possibilities. Researchers are quick to point out that it is likely a complex of all of these factors with no single smoking gun.

Where habitat change is occurring most rapidly such as in the Northeast and in Florida, populations seem to be dropping the fastest, something that I noted even 20 years ago. This might just be a harbinger of things to come for the West. We are blessed with a lot of open space, but development is slowly eating away at it to the detriment of the kestrel.

Before my wagon crosses that great divide, I could see the final demise of sage-grouse and prairie chickens to name a few. I hope though, that my great-great-great grandkids will still be enjoying kestrels. 

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Help Idaho Wildlife

When we traveled across the state in October 2017, most of the vehicles we saw using the wildlife management areas did not have wildlife plates. Buying wildlife plates is a great way for non-hunters and hunters alike to support wildlife-based recreation like birding.

C'mon folks, let's help Idaho's wildlife by proudly buying and displaying a wildlife license plate on each of our vehicles! 

See below for information on Idaho plates. Most states have wildlife plates so if you live outside Idaho, check with your state's wildlife department or vehicle licensing division for availability of state wildlife plates where you live. 

And tell them that you heard about it from Nature-track.com!

Wildlife License Plates

Great news! as of 2024, there are three NEW designs for license plates. They still are bluebird, cutthroat trout and elk, but they are beautiful.

Idaho Wildlife license plates provide essential funding that benefits the great diversity of native plants and wildlife that are not hunted, fished or trapped—over 10,000 species or 98% of Idaho’s species diversity. Game species that share the same habitats (such as elk, deer, antelope, sage-grouse, salmon, trout) also benefit from these specialty plates.

No state tax dollars are provided for wildlife diversity, conservation education and recreation programs. Neither are any revenues from the sale of hunting or fishing licenses spent on nongame species. Instead, these species depend on direct donations, federal grants, fundraising initiatives—and the Idaho Wildlife license plates.

Both my vehicles have Bluebird Plates. I prefer the bluebird because the nongame program gets 70 percent of the money from bluebird plates, but only 60 percent of the money from elk and trout plates - 10 percent of the money from elk plates supports wildlife disease monitoring and testing programs (to benefit the livestock industry) and 10 percent from cutthroat plates supports non-motorized boat access.

Incidentally, in 2014, the Idaho Legislature denied the Department of Fish and Game the ability to add new plates or even to change the name of the elk and cutthroat plates (very specific) to wildlife and fish plates, a move that would have allowed for changing images occasionally and generating more revenue. It would seem that they believe that we Idahoans don't want a well funded wildlife program.

I think it is time we let the Legislature know that Idahoan support wildlife funding and that we would like to see these generic plates come to fruition.