Birdwalks at Kent Park by Rick Hollis
Birdwalks are cosponsored by the Friends Of Johnson County Conservation and the Iowa City Bird Club are on the first and Third Wednesdays of each month from March to October. We meet at the CEC at 8:00 a.m. and wander around the park for an hour or two or go to the Bird Blind.
On a recent Birdwalk we heard a woodpecker drumming, and someone asked me what species it was. In addition to pecking at bark to get foods, woodpeckers advertise their presence on a territory by drumming on a log [or your house]. Some species can still be identified by their drums.
Two common species, the Hairy Woodpecker and its diminutive cousin the Downy Woodpecker are easy to tell apart. Both have give a pretty stead drums. While the volume will depend on how close you are to the woodpeck, they differ in the length of the tap series and inter-tap interval.
In the chart made from two average recordings from http://xeno-canto.org, you can see that the Hairy get 20 taps in ca 0.7, while the Downy takes ca 1.5 seconds to get a similar number of taps.