Just as the first warblers of spring are starting to trickle in to Maine, a sweet whistled song can often be heard floating out from amidst the still largely leafless trees.

More than one beginning birder has been fooled into thinking that the song had to that of a newly arrived warbler. Tracking down the singer can sometimes be surprisingly difficult because it is an unobtrusive bird.

The brown creeper is perfectly named. This small brown bird with white undersides moves by hooking on to the trunk of a tree like a woodpecker with its tail pressed against the bark and hitching up the tree.

Remarkably, it virtually always starts at the bottom of a tree, moving upward while searching the bark for small insects and insect eggs, which it probes and picks with its small down-curved bill.

Once it has made its way closer to the top of the tree, it lets go and quickly drops down to the base of another tree. In this way it moves through the forest, seemingly as reliant on trees for its movement as Tarzan swinging from tree to tree across the jungle.

Throughout much of the year, the only sign of their presence in a forest is the occasional, incredibly high-pitched short call note, undetectable unless listening closely for it. If you do see one, though, it’s worth keeping your eyes open, since they typically can be seen in pairs or even in small family groups when encountered in the late summer or early fall.

Brown creepers can be found in Maine year-round but despite their apparent unshakable tie to trees, a sizable proportion migrates south to the southeast U.S.

Once we were on Monhegan Island in early October watching a dawn movement of migrating birds when a brown creeper flew in and landed on the lighthouse wall, that being the closest thing to a tree trunk that the exhausted bird could find in the large open area into which it had flown after descending from nocturnal migration.

We also learned of the migratory nature of the species when we spent time in the bald cypress woodlands of Arkansas in winter in search of the hoped-for ivory-billed woodpecker. Those flooded forestlands were full of brown creepers that were very much at home as their tiny bodies moved up the six- to ten-foot wide 600-year-old cypress trees.

Here in Maine, brown creepers are equally at home picking their way up the trunks of maple and birch and beech trees, but we often picture them hitching up the smooth bark of a white pine as we remember watching them in Grandmother Chase’s pine grove in North Edgecomb.

In late March and April, the males begin singing their sweet whistled songs, which to our ears sound a little like a “miniature” version of the song of the Eastern Meadowlark. The nests are built under slabs of loose bark, where the female lays four to six eggs.

brown creepers can be seen throughout the state and throughout the Midcoast Maine area. Boothbay Region Land Trust Preserves are great spots to look for them, and last summer we enjoyed watching a family of them at the Coastal Maine Botanical Gardens.

Keep your ears tuned for that sweet, early spring song.

Dr. Jeff Wells is the senior scientist for the Boreal Songbird Initiative. During his time at the famed Cornell Lab of Ornithology and as the Audubon Society's national bird conservation director, Dr. Wells earned a reputation as one of the nation's leading bird experts and conservation biologists. Jeff's grandfather, the late John Chase, was a columnist for the Boothbay Register for many years. Allison Childs Wells, also formerly of the Cornell Lab of Ornithology, is a widely published natural history writer and a senior director at the Natural Resources Council of Maine. Together, they have been writing and teaching people about birds for decades. The Maine natives are authors of the highly acclaimed book, “Maine's Favorite Birds.”