As I indicated in the last post, April is a month for checking the forest floor, looking for and admiring the emerging spring wildflowers. April is also a month for checking dead trees or limbs as well as holes/cavities in live trees.
There are approximately 14 bird species that (always or usually) nest in tree cavities in Eliza Howell Park. The beginning of cavity nesting season might be a good time to comment briefly on a few of them.
It is not too difficult to spot Red-bellied Woodpeckers excavating holes at this time of the year. They often stop their work to call out loudly, especially the male who does most of the excavation. In EHP they often choose a large dead tree or a dead limb on a live tree. They might have used the same tree or limb before, but they make a new nest each time.
European Starlings often use old Red-bellied Woodpecker nests for their own use — and sometimes use brand new ones. I have several times over the years seen Starlings watching as the woodpeckers near completion of a new nesting hole and then move in to take it over when the woodpeckers are away. Once inside, the Starling is able hold off the larger and more powerful Red-bellied Woodpecker, which will then start over, making another hole from the beginning.
Wood Ducks breed in the park and they, too, nest in tree cavities. Contrary to Red-bellied Woodpeckers, their nests are not at all easy to find. At this time of the year, I sometimes see a pair or two moving quite high among the acres of large trees near the river, early in the morning. They are apparently “house hunting,” checking out natural cavities that they might use.
Wood Ducks do not excavate and they do not add any nesting material, so there are not many times to see them around the nest. Once the eggs hatch, the young leave the nest the next day or so (drop/jump to the ground) so there is no back and forth to the nest after hatching. So the opportunities to spot the nesting tree are few. Finding a Wood Duck nest in this park means being in the exactly right spot, at the right time, looking in the right direction.
People are sometimes surprised to learn that the little Black-capped Chickadee is a cavity nester. Perhaps the bigger surprise is that it often (though not always) excavates its own nesting hole. It frequently selects a stump, long dead and rotting. It is not able to dig into wood as well as a woodpecker, but it gets the job done.
One pair is currently working on the hole indicated below, the picture taken earlier this week from across the river.
The White-breasted Nuthatch is another small bird that nests in a tree cavity, but it does not make its own; it uses a natural cavity or an old woodpecker hole.
This is one species that will sometimes use the same nest more than one year. I am currently keeping an eye on a nesting location (a natural cavity about 15 geet up a tree trunk) used each of the last two years. If they return to it again, it will likely happen this month.
Bluebirds are well known as a bird that will nest in a box (and a pair will sometimes use a box in Eliza Howell), but it seems that they prefer other cavities here. The photo above is from 2021, when they used a hole that had been made or enlarged by chickadees a couple years earlier.
April is the usual time for Bluebirds to prepare a nest. I have been watching a pair recently. They are in the same general section of the park quite often and I am hoping that I will soon see them carrying nesting material (the behavior that usually leads me to a nest).
There are four species of woodpeckers that nest in Eliza Howell: Hairy, Red-bellied, Downy, and Northern Flicker. Downy, the smallest, is foraging in pairs now, but it is probably just a little early for them to begin a nest.
As is the case with the other three woodpecters, they excavate a new hole each time. In the case of Downies, their hole is usually on the underside of a dead tree limb that slants, that is not vertically straight, as can be seen in the photo above.
Great Crested Flycatcher
Very few members of the flycatcher family nest in tree cavities; the Great Crested is the only one in eastern North America. Its nests are in either natural or woodpecker-made holes.
Great Crested Flycatcher does not return from its winter grounds until May and begins nesting later than most other cavity nesters, after tree leaves have emerged.
Most birds make a nest outside, placing it on tree or shrub branches or on the ground, and constructing it with varying types and amounts of plant and other naterials. There is a sizable minority of species, however, that nests in cavities. They include a number of year-round residents and the cavity users tend to start earlier.
The cavity nesting season has begun.