Have you ever heard the sound of Eastern Gray Treefrogs?
They are 1-2 inches long, found across most of Pennsylvania, and absolutely adorable.
They call in spring and early summer at dusk or on rainy days, so you've likely heard their flute-like trills!
Learn more about Pennsylvania's amphibians:
http://ow.ly/g2U450Oiull
Source: PA Fish and Boat Commission
Eastern Gray treefrogs