The American kestrel is North America’s smallest falcon species and the second smallest falcon in the world. These charismatic birds often charm and entertain bird watchers across their range. They can be found from Alaska to South America and from the East Coast to the West Coast. Their colorful plumage makes them relatively easy to spot compared to most raptors, and their call is incredibly distinctive.
If you have kestrels living in your area, keep your ears open, as these birds tend to be very vocal year round, but especially so during the breeding season. Their call may be descried as a “klee” or a “killy, killy.” They also make excited chittering calls, especially between pairs. Check out this link to hear examples of American Kestrel calls.
Below are six of my favorite interesting facts about kestrels.
1) One of the favorite foods of kestrels is insects such as cicadas, beetles, dragonflies, and especially grasshoppers, which can be a benefit to farmers. They will also prey on small animals such as mice, voles, lizards, small snakes, and sometimes small birds, along with spiders, scorpions, and earthworms. Earthworms are hunted on foot after it rains and worms have surfaced from below ground. I found this observation, by Thomas Cade in his book Falcons of the World, interesting. In suburban areas of southern California, he has seen kestrels land and walk about feeding on earthworms that had crawled out of lawns onto wet sidewalks or pavements.
2) Although Kestrels prefer to hunt by sitting, waiting, and watching over an open area for prey to appear, it is not uncommon to see them hunting on the wing, using a hovering technique, sometimes called kiting. To hover, kestrels face into the wind and beat their wings, often at a fast pace, causing them to remain almost stationary in the sky as they search the ground below for prey. This method is not used as much as the sit and wait style, as it uses four times as much energy as level flight.
In this video, a female kestrel is using hovering while hunting a vole:
3) Studies have shown that kestrels can see ultraviolet light. I was a little surprised, however, when I recently read an article by the National Wildlife Federation, that kestrels are not alone in this ability, as most diurnal (active in the daytime) birds can see UV light! Researchers believe that for kestrels, this ability to see UV light enables them to vividly see the urine markings and trails that small mammals, such as voles, leave as they run along the ground. These trails and urine markings would probably look bright yellow to a kestrel, therefore alerting them to the presence of a meal.
4) Most raptors look alike when it comes to the coloring of their plumage. In most cases the female is the larger of the two birds, and one can not tell a male from a female by their color pattern. In kestrels, however, the females and males are colored differently, making it easy to tell their sex. The most obvious color difference is that males have a blue-gray wing color and usually have a solid reddish tail with a wide dark sub terminal band and a thin, white terminal stripe at the tip. The females tend to be brown with black barring all over, including a tail with many thin dark bands.
5) Both female and male kestrels have the same head markings in common. They tend to have a face with white cheeks, and they all have two vertical black stripes often known as mustaches but technically called malar stripes. There are also two additional black spots on the back of their necks. These are called “ocelli.” The most common theory about these spots is that when a kestrel is seen from the back, or from the front when the bird is bent over working on prey, the ocelli resemble false eyes. This may confuse or deceive predators into thinking that the kestrel is looking at them, therefore causing them to believe that the element of surprise is gone and going after the kestrel would be unprofitable. Another theory is that the ocelli may help to keep small birds from mobbing them. A third thought, which is reported in the book, Falcons of North America by Kate Davis, suggests that the false eyes help to strengthen pair bonding between mates, because they appear to be constantly gazing at each other. She prefaced this as a “somewhat romantic speculation.”
6) Kestrels cache (hide) uneaten kills in places such as tall grass clumps, tree roots, bushes, cavities, or in tree limbs in order to hide it from thieves and save it for times when food is not available. Unlike other falcons who tend to cache mainly during breeding season, kestrels cache food year round. This can be important when raising chicks during nesting times as the cache helps to ensure that chicks can be fed even when a hunt is unsuccessful. Outside of their own caches, kestrels rarely feed on carrion but will return to their own caches within a few hours or days. The Raptor Rehabilitation of Kentucky reported that a female kestrel was observed killing and stashing twenty mice that were provided by scientists.
Question from Visitors:
Do falcons need to drink water?
I was asked this question once by a visitor when discussing Hayabusa, our peregrine falcon, and the fact that in the wild they may live on high cliffs overlooking open land. I thought it was an interesting question, and one that fits many other raptors, including kestrels. Falcons get the majority of the water they need for survival from the food they eat. They do, however, like to drink water and also will bathe if a water source is available in a safe location.