CLOUDCROFT CHECKERSPOT/FRITILLARY

[Chris J. Durden]

At 10:26  5/01/00 GMT, you wrote:
>In article <3.0.5.32.20000103091412.007e1a60 at mail.utexas.edu>
>           drdn at mail.utexas.edu "Chris J. Durden" writes:
>
>>   Regarding this population of *Euphydryas (Occidryas)* whether it is
>> endemic subspecies or species, its range elswhere in these mountains should
>> be assayed before restrictions on sampling are imposed.
>
>What do you mean by "sampling" ? Perhaps you could clarify this?
>In biological terms I believe it is equivalent to predation.
>
- - -
  By sampling I mean that samples should be taken serendipetously (when
they are available), with precise data recorded and that they should be
invested in our museums so they are available in future to provide
information that will help answer questions we have not even thought of yet.
  A sight record produces no verifiable identification, no chemistry or DNA
residue. 
  Listing a species would preclude the identification of new colonies by
sampling because we cannot predict when they will have populations abundant
enough to be noticed. Because of this there is no lead time to obtain
permits for sampling. This is the serendipetous factor.
  Listing a location for a species, if this were possible, would provide
primary protection for the species while leaving open the opportunity for
chance discovery of new locations for the species by the exploration of
casual collectors.
  I think the benefit of discovery of new sites that can then be protected,
far outweighs the effects of take by responsible casual collectors. 
- - -
>> A large portion of
>> the mountains are included in the Mescalero Apache Reservation, beyond the
>> jurisdiction of the USFW, if I understand the situation correctly. Not too
>> long ago a large fire swept through coniferous forest on the reservation,
>> destroying cover and opening up the area to sheetflood erosion and burial
>> of the rare gulch wetlands under sediment washed off slopes. This I see as
>> a far greater hazard to the habitat of this population of *Euphydryas* than
>> any of the development at Cloudcroft.
>
>I don't think this is valid. I don't know the area so I can only comment
>on what the known population dynamic models tell me should be done.
>
> I find this difficult to answer here particularly
>in text form. The population dynamic systems of checkerspot butterflies
>are phenomenally and fascinatingly complex. Niklas Walhberg is an
>undoubted expert in this area so no doubt he will correct any inaccuracies
>in my less expert analysis.
>
>Checkerspot populations exist in metapopulations. These are linked groups
>of colonies where individual colonies become extinct to be eventually
>colonised from their neighbours. The classical model of metapopulation
>dynamics postulates that  the number of occupied patches P at a given time
>t is given by dP/dt=cP(1-p)-eP where c and e are colonisation and
>extinction rates. Now there are two important things that this 
>says. 
>
>1 EMPTY habitat is a fundamentally inherant component
>of the system. So suitable but unoccupied habitat in the vicinity of
>occupied habitat must be conserved.
>
>2. If you simplify the equation you find that the equlibrium value of P is
>given by 1-(e/c). In other words if you increase the extinction rate the
>number of occupied patches will fall. (This is fairly obvious if you think 
>about it.)
>
>What we do know from the work that has been done in Finland on Melitea
>cinxia (Known in Britain as the Glanville Fritillary but in reality
>a checkerspot.) is that one of the major causes of population extinctions
>is predation. Specifically in this case it is attacks by the parasitoid wasp
>Cotesia melitearum, but it really does not matter what the predation is
caused
>by. "Predator not equals Homo sapiens" is not written into the mathematics.
>Predation leads to an increased extinction rate. If you want to increase the
>stability of the metapopulation you avoid anything that increases predation
>because it decreases the stability of the system.
>
>Now coming back to why the proposed development at Cloudcroft is harmful.
>
>The equation I showed  can be developed further in order to calculate
>the minimum size of a network of habitat patches that will work, and
>how many need to be occupied. What the mathematics boils down to
>is that 3 times the Square Root of the total number of  habitat
>patches must be occupied. If you do the sums the absolute minimum viable
>system is 10 patches, all occupied. This is an absolute minimum in perfect
>theoretical conditions. Now nature will vary from the perfect mathematical
>model because it makes assumptions that all habitat patches are similar
>but what it does indicate is that a considerably larger amount of habitat
>is required in a given area than might at first seem obvious.
>>From this you can also see these occupied patches that are threatened by
>development at Cloudcroft are particularly valuable to the integrity of the
>system.
>The last thing that should be done if this creature is to be conserved
>is to allow the destruction of key important parts of its population
>before their value is even known. The exact parameters which are required
>to know this are difficult to obtain. Do we know, for example, which if
>any specialist parasitoids attack this animal? ( The indications are 
>that there should be only one, probably a Cotesia species.)
> What are the population dynamics of its host plant? The only safe solution
>is to be cautious.
>
>If we get this wrong the result is irreversable. This butterfly will
>join the Great Auk, the Xerces Blue and Dodo in oblivion. 
- - -
  I understand all this. I agree with it. You are however applying theory
to a known metapopulation of one site (from the data we have been given).
Surely the emphasis should be to encourage the discovery of additional
sites and to map the extent of the metapopulation. The last thing we should
do is legally lock up the subspecies/species so that additional work on it
is inhibited.
........Chris Durden 


>
>-- 
>Neil Jones- Neil at nwjones.demon.co.uk http://www.nwjones.demon.co.uk/
>"At some point I had to stand up and be counted. Who speaks for the
>butterflies?" Andrew Lees - The quotation on his memorial at Crymlyn Bog
>National Nature Reserve
>
>