Chorus frogs are best observed at mating time. They are darned hard to find
other times of the year.
I would expect that frogs in the lowland areas will be mating before frogs in
higher elevations.
Try a google search. There are sound files of their calls in a lot of sites so
you know what to listen for. And check if Colorado has a native amphibian page,
our state posts maps of locations of all species of frogs. And someone
published a book of amphibians of WA and OR so you might search and see if
there is a like book available for Colorado.


kathy :-)
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