Cope's Gray Treefrog (Hyla chrysoscelis) generally replaces Gray Treefrog (Hyla versicolor) throughout the coastal plain in Maryland, including most of the Eastern Shore. The dividing line for the two species is roughly the Fall Line (think Rte. 1), with Cope's to the east. The species are so similar that they are best distinguished by voice and range. MARA did find plenty of outliers to this general rule, so voice confirmation is ideal (and necessary in central Maryland).