Spring migration continues, with many birds returning to the area for the season as well as untold numbers of birds headed farther north for to take on their seasonal obligations.
Recently arrived yellow-billed cuckoos can again be heard calling in our area. A sleek, beautiful bird of forested areas, cuckoos spend most of their time in the tree canopy foraging among the branches and foliage for invertebrate and small vertebrate prey. They are quite fond of caterpillars, especially tent caterpillars. A curious habit of calling in advance of an approaching rainstorm led to an old common name of “rain crow” for the species. Unlike many cuckoo species of the Old World, our North American species are not nest parasites, and raise their own offspring.
Eastern wood-pewees are among the birds currently making their way into and through our area. Named for their unmistakable call, pewees are a type of flycatcher, and spend their time foraging for primarily flying insects in wooded habitats. Occasionally one of these small birds may be found alongside an unimproved road through a forested area using a favored branch as a perch from which to ply its trade.
Much to their chagrin, recently some folks have reported backyard bluebird nesting attempts that have gone awry. Eastern bluebirds can be fairly common around the residential areas where we live, and can be attracted to many backyards merely by supplying an appropriate nest box.
When pacing a nest box for any birds to use, the first thing to note is it should never be mounted on a tree. A number of native predators will pilfer any bird nest, and bluebirds are susceptible to many of them. Among the most frequent bluebird nest predators are several snake species, primarily rat snakes and black snakes. These snakes can be quite arboreal in their habits, and a nest box mounted on a tree is an open invitation to come and dine.
Raccoons and squirrels will also readily depredate a bird nest box. Some years ago, a friend did a study of bluebird nesting success in which boxes mounted on trees and boxes mounted on free-standing posts/poles affixed with predator baffles were monitored. The results showed over 90 percent of the nests in tree-mounted boxes were depredated at some point.
Nest boxes should also be designed with some provision for ventilation. Most (but not all) commercially available nest boxes are constructed with a provision to allow the circulation of air. Lastly, if you feel the need to paint a nest box (it's not necessary,) only use paint clearly labeled as non-toxic.