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Hi All, July 31, 2008
I would like to add a few personal comments on frog decline,
especially Rana pipiens. Drawing on personal experience, I think there
has been a huge decline in R. pipiens over the last 60 years and I think
it can be directly attributed to habitat loss; especially dewatering of
landscapes.
To take one example, on the Cornwallis meadow of our family farm in
the late 40's, there was a swail of about 3/4 acre that we mowed by
hand, and then carried the cut hay to dry ground, because the swail was
always too wet and soft for a horse. This would have been in mid- to
late August after all of the hay on dry ground had been cut, made and
hauled. With every swing of the scythe there would be a plop, plop,
plop, plop, as frogs (presumably Leopard Frogs) jumped out of the way
and a wake of frogs as one walked out with a forkful.
That swail, wet year round in the 40's, dried up decades ago due to
dewatering of the landscape by human activity and the formerly abundant
frogs are no more.
The same goes for a large temporary pond that was created by
dewatering; lots of Leopard Frogs in the early 50's, an alder swamp by
the early 60's and scrub woodland by the late 70's. Once again it was
Frog moving day with no place to go.
The swail is interesting from another viewpoint. It was unusually
well aerated although I did not recognize that at the time. Swails often
have a certain air about them; H2S. This swail, being fed by
ground-water flow from a sump about 1/2 mile away which in turn fed a
never-dry woodland runnel which dead-ended in the swail, did not stink
at all. [When carrying wet hay the least tiring way is to raise the fork
over the head, bend forward and then lower part of the weight onto head,
neck and upper back, so you quickly become wet with, in this instance,
refreshing and un-stinky swail water.]
I have wondered since whether or not the localized abundance of
frogs in this swail, as compared to the average poorly aerated swail,
was due to the good aeration.
In more general terms, I think Joe South said it best in the song
'Don't it make you want to go home'; "Now...the river don't flow like it
did in my childhood days".
Yours truly, Dave Webster, Kentville
James W. Wolford wrote:
> Steve & Randy & Chris et al.,
>
> Check out the N.S. Herpatlas home page at
>
>
> http://landscape.acadiau.ca//herpatlas
>
>
> [Nova Scotia Herpetofaunal Atlas Project ("herpatlas")] -- see links
> to species names and identification tips and photos and calls etc. etc.
>
>
> P.S. Randy's "ribbit" fits only the Pacific Treefrog, thus is humorous
> but out of place here.
>
>
> Steve's comments on the Northern Leopard Frog are interesting -- I
> have no up-to-date information, but I believe the cause of the decline
> which started or happened a decade or two ago is still unknown, and
> very unlikely to involve the chytrid fungus that infects amphibians'
> skin all over the world now, including western Canada and western states.
>
>
> Here is some quoted information from "Reptiles and Amphibians of
> Canada" by Chris Fisher, Amanda Joynt, & Ronald J. Brooks -- 2007,
> Lone Pine Publishing:
>
>
> "During the mid- to late 1970s, [the Northern Leopard Frog]
> experienced localized extinctions that were more extreme and
> widespread as one went west from Ontario. The reasons for the decline
> remain simply guesses. In some areas populations have recovered, but
> elsewhere, especially in British Columbia, [it] has not recovered.
> Although some amphibians are well known to be in decline, it is
> alarming that one of the most conspicuous frogs in Canada should also
> be in decline, particularly because there is no explanation for it."
>
>
> The ground colour of N.S. Leopard Frogs is quite variable but usually
> a fairly bright green, with brownish much less common -- latter colour
> or grayish is more common in Pickerel Frog.
>
>
> Back on the Green vs. Bull Frogs, another species for confusion is the
> Mink Frog, which is sometimes difficult to tell from the Green Frog --
> see tips in field guides or herpatlas site re colour and broken
> dorsolateral ridges and calls like "cut,cut,cut...".
>
>
> I'm forwarding to John Gilhen and Fred Scott for possible comments.
>
>
> Cheers from Jim
>
> Begin forwarded message:
>
>
>> From: Randy Lauff <randy.lauff@gmail.com <mailto:randy.lauff@gmail.com> >
>>
>> Date: July 28, 2008 5:02:19 PM ADT
>>
>> To: naturens@chebucto.ns.ca <mailto:naturens@chebucto.ns.ca>
>>
>> Subject: Re: [NatureNS] Frog over-population?
>>
>> Reply-To: naturens@chebucto.ns.ca <mailto:naturens@chebucto.ns.ca>
>>
>>
>> Steve,
>>
>>
>>
>> The Green Frog is Rana clamitans (
>> http://commons.wikimedia.org/wiki/Image:Green_Frog_Rana_clamitans_2448px.jpg
>> ). It is relatively common (up my way anyway) and is easily localized
>> by its banjo-like call. The Green Frog is more aquatic than the
>> Leopard Frog, which I routinely find on land.
>>
>>
>>
>> Ribbit!
>>
>>
>>
>>
>> 2008/7/28 Stephen Shaw < srshaw@dal.ca <mailto:srshaw@dal.ca> >
>>
>> OK but what's a "green frog"?
>> I think this nomenclature started on this current thread with
>> Jim, but as a
>> resident alien species (me not the frog), I'd not heard that name
>> before. Do
>> you mean the usually-named Northern Leopard Frog (Rana pipiens),
>> aka meadow or
>> grass frog, or is Green Frog a different species? If it is the
>> same species
>> (R. pipiens), is Green Frog a colloquial name restricted to the
>> Maritimes? On
>> the appropriateness of the name if it is the same as R. pipiens,
>> the base
>> colour (on which there are usually spots superimposed) often is
>> not green but
>> light brown, as someone else remarked earlier.
>>
>> On the original question of overpopulation, R. pipiens has almost
>> disappeared in
>> western Canada (BC and AB) since the 70s, but seems not to be
>> threatened in
>> central Canada; not sure about the Maritimes. The cause of
>> western decline in
>> this particular species seems uncertain from the little I've
>> read. Maybe also
>> a chytrid (spelling?) problem spread originally from clawed frog
>> Xenopus to
>> other amphibians, or else a debilitating trematode parasite?
>> Does anyone on
>> NNS have specialist info on the cause of decline for this
>> species, as opposed
>> to that for amphibians generally, worldwide?
>> Steve
>>
>>
>>
>> Randy
>>
>> 'gonish.
>>
>
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