Lifestyles

Of a Feather: What some birds did before buildings

By BILL CHAISSON
By Bill Chaisson

I have been walking in a timber cut quite often because I am interested in the effect of the removal of all those trees on what bird species are present. The parcel had already been logged when I moved to Sutton, so I don’t know who lived there before. So, my baseline is the first year post-cut. The new openings in the forest are filled with herbaceous plants, woody shrubs, and saplings, although there is also a lot of unvegetated ground covered with wood chips and pieces of the crown that were left behind.

I was surprised to find eastern phoebes here. I have never thought of them as “forest birds” because of their well known fondness for nesting on man-made structures like bridges, barns, and ledges on the exterior of houses. You might mistake a phoebe nest for a barn swallow effort. According to allaboutbirds.org, the female flycatchers build them of “mud, moss, and leaves mixed with grass stems and animal hair.” They are either placed on a flat surface or attached to a vertical wall with the smallest of protrusions to prop them up. Phoebes may reuse them in subsequent years or they may be taken over by barn swallows.

Where did phoebes put their nests before there were bridges, barns and houses? On rock outcrops. As it happens, this timber cut is filled with vertical faces of bedrock, some of them 20 or 25 feet high. Phoebes rarely build their nests higher than 15 feet from the ground and prefer the site to be masked by woody vegetation.

There are also wood pewees on this property. I don’t think I have seen the two flycatchers together before. Phoebes may have dispersed from the yards that line the nearby road, but pewees would likely have already been there. They are fond of forest openings and edges; the local population seems to have responded well to having several acres become a series of clearings. Unlike phoebes, pewees nest in trees, placing a bowl of woven grass encrusted with lichens in a deciduous tree, usually higher than 15 feet from the ground.

My sense is that I am seeing the pewees further into the cut, nearer the continuous forest that surrounds it, and seeing the phoebes closer to the road, where there are larger open spaces, the “landings” that loggers create as waystations during the process of hauling the timber out.

I mentioned barn swallows above. Where did they nest before there were barns? In caves. There are probably still more barns in North America than there are caves, but there was a time when there were even more barns than there are now. Their breeding range expanded across the continent in concert with the European settlement of North America. Hirundo rustica numbers have declined 46% since 1966, according to the North American Breeding Bird Survey, but they are still quite common. Molecular genetic studies have shown that populations in the Old World have also expanded across Asia in response to development of cultures that erected suitable structures.

Barn owls aren’t as wed to barns as swallows. They “put their nests in holes in trees, cliff ledges and crevices, caves, burrows in riverbanks, and in many kinds of human structures, including barn lofts, church steeples, houses, nest boxes, haystacks, and even drive-in movie screens,” according to allaboutbirds.org.

Given this broadmindedness, it is not surprising that unlike the swallow, barn owl numbers have held steady over recent decades and perhaps increased slightly. It is not, however, found in New Hampshire. The first recorded sighting was in 1950 at Belmont, and a pair bred at Hollis in 1977. There have been scattered sightings since, but we remain north of their breeding range.

Two other swallows are closely associated with man-made structures. The famous colony at San Juan Capistrano mission are cliff swallows. After almost two centuries of faithful use, during the 1990s the nests were removed during a restoration of the mission buildings. The birds opted to build elsewhere in town and have not yet returned, although efforts have been made to entice them.

Cliff swallows were western birds but dispersed east in response to European settlement. Isolated colonies now exist from maritime Canada down the Appalachians and through the Great Lakes. Early explorers of the American West found enormous colonies on cliffs facing rivers across the Great Plains. Unlike the barn swallow, which builds an open cup of mud and straw, the cliff swallow nest is enclosed and gourd-shaped.

Purple martins depend almost entirely on the large “apartment house” nest boxes built for them, especially in the eastern part of their distribution. Out west they can still be found nesting in hollow trees, but widespread logging has reduced availability of old “unhealthy” trees. When it comes to man-made structures, western birds seem to prefer groups of gourds hung on cross-trees to houses.

Martins are uncommon in New England today. In New Hampshire they are largely confined to Merrimack, Belknap and Carroll counties. Historically they were more widespread in the region, but in the 19th century several periods of cold, rainy, spring weather devastated colonies. According to the “Atlas of Breeding Birds in New Hampshire,” the species has not recovered from a 1903 incident. The gradual long-term disappearance of open agricultural land limits where they can forage has also contributed to their decline nationwide, with numbers down 37% since the mid 1960s. They remain most common in the Southeast.

In the coming years I hope to monitor changes in the nearby timber cut. It will be interesting to see how many years the phoebes will remain. The cut at the base of the Lincoln Trail on Kearsarge Valley Road is a year older, and the logged areas there are already full of raspberries and other woody plants. Soon the rock outcrops in the cut near my home may not be acceptable nesting sites.

Bill Chaisson, who has been a birdwatcher since age 11, is a former editor of the Eagle Times. He now works for the Town of Wilmot and lives in Sutton.

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