Here is a sample of a Gray Treefrog, Hyla versicolor aggressive call, it is easier to hear if you wear headphones due to the overpowering trill of the main broadcast call. The call is a series of short peeps in the 4,500hz to 4,800hz range. This call occurs when 2 males are in close proximity of each other. There are several videos on YouTube demonstrating this call and the frogs relative positioning to each other. This recording was captured June 10th, 2010 in the Boston Township region of the Cuyahoga Valley towpath with the chorus originating from the canal.