Cottage Q&A
QUESTIONI would like to build a purple martin house for the cottage. The plans I've seen call for plywood, but I would like to reduce the overall weight by substituting aluminum sheeting for the non-supporting members, such as the dividers and side walls. Is there anything about aluminum sheeting that would stop the birds from using the house?
ANSWER
Aluminum sheeting would not likely stop the martins from choosing your house for nesting. Many commercial purple martin houses are built with aluminum. Nevertheless, Mark Peck, an ornithologist with the Royal Ontario Museum, has some concerns about using the material in cottage country, where a sudden cold snap can happen even in late May or early June. While wood is a pretty good insulator, metal conducts heat rapidly. Since martins start returning as early as late April, and may be nesting by mid-May, eggs, nestlings, or even the adult birds could be fatally chilled by a change in the weather. By the same token, an unseasonal heat wave could create an oven-like interior, which would be equally dangerous to nesting birds. Casey Evans, who works for the Purple Martin Conservation Association in Edinboro, Penn., agrees that wood offers better protection against cold and heat but doesn't see any problem with using aluminum sheeting as long as you insulate the roof of the building. "You can use any type of insulation - polystyrene, spray foam, or batts - provided it's covered so that the birds can't pick at it," she explains. "Cover it with a subroof or seal it inside the attic of the birdhouse."
* Published in the April/May 2003 issue of Cottage Life
