Pacific chorus frogs (actually should be Pacific tree frogs if we use Hyla
for their name) probably are territorial, as many other frogs are, and they
seem to call to protect roost sites or hidey holes. At least that's what the
squirrel tree frogs that I grew up with in Florida do. That call is a
different one indeed from their breeding call, often given during the
off-season. And when it's in the 50s around here, it's plenty warm enough
for an amphibian to function.
Dennis Paulson

> While we're on the subject of cold blooded critters - I have a question
> that has perplexed me for years; Why do the pacific chorus frogs, hyla
> regilla, vocalize in the winter? It is a different vocalization than the
> one used when they return to water to breed beginning in March. It sure
> seems that they sometimes call in response to bushwhacking or pishing.
> Could it possibly be territorial? If so, why do they need a winter
> territory?
>
> Dave Parent, dpdvm at whidbey.com, Freeland, WA