'Chimney caps, vent pipes, gutters': Why some woodpeckers are major metal heads

Woodpeckers primarily do this during the springtime breeding season, and their metallic racket has two purposes, "basically summarized as: All other guys stay away, all the girls come to me," McGowan said. "And the bigger the noise, the better."

Over time, some urban woodpeckers have learned that metal is more resonant and reverberant than wood, and amplifies sound much more than trees do, he added.