skullbaby wrote:
>hey
help me out here. We have a resident
>population of Rana viridiana frogs in our city
>park, and it looks like they're dying off
>suddenly. Any ideas? Anybody got experience
>with something like this?
Your situation sounds similar to what's happening
to the red-legged frog, Rana aurora, here in California, and
in some sense to frog populations all over the world. There have been
very worrisome declines in frog populations reported over the last 15
years or so.
But
it isn't like something is killing off all frogs -- because at the same
time, some frog populations are thriving, and sometimes one group of
frogs will die off while another group of frogs of the very same species,
who live nearby, remain stable.
It
seems likely to me, and to others who study frogs, that there are several
factors that are combining to put stress on frog populations. An increase
in UV radiation, global warming and changing weather patterns, increases
in pollution, a resurgence of parasites -- these are probably all factors
in a global sense.
But
in your case, with such a sudden drop, one of these global causes is
probably not to blame. It sounds like you have something specific and
local. I would ask myself these questions:
- Is
there some new source of water pollution?
- Is
there a significant change to the frog's environment?
-
Are there signs of some other species taking over the frog's territory?
(Usually a "weed" species that adapts well to new environments)
- Are
there people around who weren't around before?