Wednesday, April 21, 2010

Group Building Nest Boxes Around Gowanus

A group of young architects has been installing yellow nest boxes for birds around the Gowanus Canal in Brooklyn.

With growth has come sophistication. At first their boxes were built with the rough idea of attracting a common songbird, the Eastern Bluebird, but since working with John Rowden, this changed. Rowden, an ornithologist with the New York City chapter of the National Audubon Society, suggested a more targeted approach.

“Most of my work is in areas a bit more natural than Gowanus,” Rowden joked. He advised the team against attracting bluebirds, which are not typically found so close to water, and to focus instead on birds such as chimney swifts, known for their insect-eating abilities, and on a small falcon called the kestrel.

A dramatically patterned bird with contrasting gray wings and a copper-colored back, the kestrel doesn’t build its own nest, but instead uses natural crevices or manmade boxes it finds. It’s a predator that hunts rats, patrolling its domain by hovering in place on outstretched wings.

“If people know wildlife is in the area, they’d appreciate it more,” Rowden said. “If people see wildlife, they’d know industrial areas are not as dead as everyone thinks.”

Since the spring of 2009, the Nest Colony group joined the Gowanus Canal Conservancy, and their members started participating in the Conservancy’s monthly volunteer cleanup events on the canal. There, they demonstrate their birdhouse-building techniques while encouraging the public to think of other ways to benefit the canal. Also, with the Conservancy’s support, they were able to secure grants that allowed them to build more birdhouses over the course of last summer.
So far the group has installed 21 nest boxes; their next goal is to build five 12-foot nesting chimneys for Chimney Swifts. They also hope that Tree Swallows will use some of the smaller boxes.

I am glad to see that the group is taking advice from some ornithologists, as that should make it more likely that their efforts will be useful to birds. The target species seem appropriate for an urban setting. The American Kestrel is declining in much of the northeastern U.S. and might benefit from some assistance. Likewise, Chimney Swifts have been in decline because changes in chimney design have reduced nesting sites.

The choice of color for the nest boxes seems a bit odd. While bright yellow does look cheerful against the decaying industrial buildings, most advice I have read suggests using plain, untreated wood for nest box construction. I am not sure if painting the boxes will discourage birds from using them or increase nest predation in an unnatural setting like the Gowanus Canal. It still seems inadvisable.

The article mentions that American Kestrels will eat rats. Perhaps some New York City kestrels have been observed eating rats, but I would expect kestrels to pursue smaller prey. According to Birds of North America, an average kestrel's diet is composed of 74% invertebrates, 16% mammals, 9% birds, and 1% reptiles and amphibians. Major prey animals include grasshoppers, cicadas, beetles, dragonflies, spiders, butterflies, moths, voles, mice, shrews, bats, and small songbirds. I did not see any mention of rats, either in Birds of North America or in my raptor books.