It’s a one-day migratory bird population count that takes place May 12, which also is International Migratory Bird Day. Birders are invited to peruse their counties, counting all birds encountered and keeping track of miles traveled and time spent counting. The 24-hour counting period starts at 12:01 a.m.
Totals are sent to county compilers who will report to a state compiler. An annual report is published in Pennsylvania Birds, the journal of the Pennsylvania Society for Ornithology.
In 2011 there were 903 observers from 53 counties. They counted 199,120 birds of 238 different species in more than 2,932 field hours.
Collection forms and compiler addresses are available online. Results can be submitted by e-mail or snail mail.