Busy Mating Season for Island Kestrels

How exciting to see so many American Kestrel couples courting and mating this spring.

It wasn’t like I was creeping around in the woods to spy on them. Starting in February, I started seeing them along the road pairing up on power lines and the tops of dead trees.

Kestrels ordinarily like to hunt from high perches. With their sharp eyesight they can easily spot unsuspecting prey from a long distance. But during mating season the kestrel couples were often sitting close and looking at each other. 
Since I don’t often get to see breeding behavior in birds, I was eager to spend time quietly watching what they were up to. Although a few of my friends began to suspect I was becoming an avian voyeur, others understood my scientific interest and invited me to come by and observe pairs of kestrels hanging out near their houses.

American Kestrels are small falcons. The ones in the Virgin Islands are year-round residents, but these are common western hemisphere birds that nest in varied habitats from Alaska down through South America.  

They are usually solitary except during mating season. Becoming a couple is the first step in their breeding process. Males try to impress would-be mates by doing fast-paced climbs and dives, and offering gifts of food. In the Virgin Islands, the gifts are usually lizards, and occasionally a mouse.

The easiest way to tell the difference between the sexes is that males have brown backs and blue wings and a solid dark band across the bottom of their tails. The females have brown backs and wings, and cross-hatching on their tails. They both have dark marks on their white chests, but there are more marks on the females, and more of the marks are shaped like streaks rather than spots. Even knowing this, though, it is still sometimes hard to tell the difference when you see the birds from a distance or in the air.  

I watched one pair off and on from February through April as they mated enthusiastically near a tree with a hole in it in a friend’s yard. They had picked out this tree as an appropriate place for their nest, and stayed close to it. Kestrels are cavity nesters, so you won’t find them making structures out of sticks. It also means you can’t see anything that’s going on inside the nest.

Both the male and female occasionally went in and out of the hole, and then one day in late February it looked to me like the female might be laying an egg. She perched on the edge of the hole, made motions like she might be pressing something out, then turned around to look inside to check on the result. What else would she be doing?

I starting counting how many days it would take for an egg to hatch (about a month) and once hatched, how long before the fledglings would come out (another month).

Despite the coronavirus quarantine, I checked back regularly and also got reports from my friend. The kestrels mated several times a day, and both ate lots of lizards, many of which suffered gruesome deaths. 

We waited eagerly for signs of babies, but by the time they should have hatched, it was very quiet by the tree hole. If there were any babies in there, the parents would need to be going in and out feeding them. Instead they had stopped even going near the tree, though they did continue to mate pretty often for a while.

Maybe there were never any eggs, or maybe something got to them. I even wondered if the hole was too deep, really more of a crack, and the eggs fell way down inside. Eventually, I sadly gave up hope. By May, those kestrels had drifted off. 

Meanwhile, another friend close by said he was seeing a lot of kestrel activity at a tree in his yard. A second chance! Before long, I had set up a viewing site in a cramped spot underneath his house. 

Soon I was delighted to see a mother kestrel show up with a lizard, which she took inside a large hole in the tree. After she disappeared, I thought I heard faint peeping sounds, but couldn’t be sure the noise wasn’t coming from some little birds I saw at the top of the tree.

If there were already babies inside the tree getting fed, I figured they would be ready to come out within a few weeks. I didn’t want to miss that. Fortunately my neighbor was happy to have me as a frequent visitor, even (or maybe especially) if I stayed under the house. Often he greeted me encouragingly by saying that one of the parents had just been there to bring a lizard, after which I waited in vain for some new activity. 

When I did actually see one of the parents come by, I was now sure I heard a chorus of peeps from inside.  

Finally, one afternoon in the middle of May I was rewarded by the sudden appearance of a little head peeking out of the hole. I was so excited I jumped up and knocked my head on a floor beam.

Soon both parents were coming by to feed the nestlings, and they didn’t bother to go inside and divvy up the lizard. They just dropped it into the hole and quickly flew off, while the peeping cries got louder and harsher.

After about two weeks, I saw one of the young kestrels climb out of the hole, grip the edge tightly, and then tentatively flap his wings before tumbling back down inside.

As they got bigger and braver, I could see that there were three of them in there. By the end of the May, the young kestrels were ready to move out. First a male one climbed out of the hole, crept up the tree trunk, and sat on a stumpy branch. He stayed there for quite a while flapping and squawking, then seemed to start looking for bugs on the branch. Soon he moved further up in the tree, and the other two emerged. By the time I left they were high up and hidden in the tree.

A few days later they had all abandoned the nest hole, but I still could hear them crying out nearby. Parents usually help feed their fledglings for about three weeks.

The parents also still need to protect their babies. Out of the nest, but not yet experienced at flying, the fledglings could be easy prey for the neighborhood red-tailed hawk. Several times I heard a hubbub overhead and saw one of the kestrels loudly flying at the hawk, trying to force the larger bird to move on.

It seems like the family is still around because I hear more kestrel calls than usual, even when the hawk isn’t here, and sometimes see them flying overhead. I imagine the young ones are learning to catch their own lizards. I was grateful to be able to spend so much time with them, and hope they will come back to this area again next year.