A mysterious, fascinating bird skulks within our forests. It is approximately the size of a blue jay. By day, it is largely silent and secretive. Observers lucky to see it often describe it as sluggish. After dark it is active, engaging in vocal night flights during the breeding season, leading some researchers to label the bird as nocturnal.

It has also been reported to vocalize before rain, earning it the nickname “rain crow.”

It consumes large quantities of caterpillars, many of which have sharp spines. These spines become embedded in the bird’s stomach lining, accumulating and eventually impeding digestion. The stomach lining is then shed and regurgitated in a pellet, along with the spines-the bird apparently none the worse for wear.

Its young are born completely naked and blind (eyes are closed until they are two days old), but are strong enough to pull themselves up onto twigs using their feet and bills within three hours of hatching.

Many other birds are born sparsely or fully covered with downy feathers, which are gradually replaced by actual body and flight feathers in an ordered, regular pattern. Not so this bird. At six days of age, it resembles a porcupine, its body bristling with long feather sheaths. At seven days these sheaths abruptly burst open, and suddenly the nestling is fully feathered.

By the eighth day the nestling has fledged, but remains flightless for an astounding two more weeks. It is extremely agile and strong, able to travel long distances through the bush. When threatened, it adopts a posture reminiscent of the American bittern, a large, heron-like waterbird: it elongates its body, points its bill skyward, and freezes, its wide-open eyes staring.

Its name has appeared numerous times in popular culture, used to describe someone as “crazy,” and also ascribed to those old fashioned, eccentric-and annoying-clocks.

It’s the cuckoo.

More specifically, it’s the black-billed cuckoo, whose signature call issuing from the woods bordering a marsh in Old Town inspired this column. This led me to their intriguing life history in the “Birds of North America” species account.

Besides the black-billed, there are two other cuckoos that breed in North America: the mangrove cuckoo, which is primarily a resident of southern Florida, and the yellow-billed cuckoo. Both the black and yellow-billed cuckoos have ranges that extend from the eastern United States and Canada to the Midwest, but the black-billed cuckoo has a more northerly range and is more common in Maine (except the very southern portion of the state) than is the yellow-billed cuckoo. However, sightings in northern Maine of the yellow-billed are not all that uncommon during migration, with many being seen on the coast (I recall seeing reports from Mount Desert Island), and more recently in Orono.

It’s a rather drab-looking bird, to my mind resembling a cross between a mockingbird and a vireo. Historically it was listed as abundant, but has undergone drastic population declines in the 1980s and 1990s. Habitat degradation is one culprit, possibly along with the use of pesticides to eradicate some of the birds’ main food sources-“pests” such as the eastern tent caterpillar and gypsy moth.

Its reproductive success seems to be tied to outbreaks of the above insects, as well as to cicada population peaks. At these times the cuckoo lays many more eggs, often depositing them in other cuckoos’ nests or in the nests of birds such as the chipping sparrow, American robin, or Northern Cardinal. Interestingly, the cuckoo only lays its eggs in nests of birds whose eggs are similar in color to its own.

The swift and unusual development of hatchling cuckoos is also in response to this often-times patchy food resource. All in all, this drab bird that skulks within the forest, giving its soft “cu-cu-cu” call, leads an incredibly fascinating life.

Corrections for great egret column: The great egret is a common sight in Southern Maine. Sightings elsewhere in the state are an unusual treat (by the way, there have been several reports of a great egret in Mt. Hope Cemetery in Bangor recently). … The photo by Jan Fiala was taken at Taylor Bait Farm in Orono.

NEWS bird columnist Chris Corio can be reached at bdnsports@bangordailynews.net