These field trips on Friday 9/21, Saturday 9/22, and Sunday 9/23 are part of the American Birding Expo https://www.americanbirdingexpo.com/

John Heinz NWR has the highest diversity of birds recorded in Philadelphia. This time of year is prime for warbler, vireos, flycatchers as well as shorebirds.
https://ebird.org/hotspot/L504403