Conditions for Overcollecting

[Chris J. Durden]

  Now this is a really sensible approach. Bravo! I suspect that if a DNA
sample of *S. idalia* were required from your colony, you might be
persuaded to permit the supervised taking of one male, scheduled in a boom
year. By the way, what is your third critical species and its requirements?
........Chris Durden

At 09:34  3/01/00 -0500, you wrote:
>Bruce asks a question that I have pondered quite a bit over the last few
years in
>my role as gate-keeper for some of the most significant natural areas
remaining
>in Indiana.  My dilemma has always been, (1) how to get inventory of
poorly known
>taxonomic groups completed on these reserves, while (a) not jeopardizing
any of
>the taxa which may both depend upon the natural area for regional persistence
>and  (b) which might be vulnerable to collecting pressure.   Here is what
I've
>come up with.
>
>Populations (not species) are vulnerable if they meet certain requirements:
>
>1) populations are isolated, such that gene flow, recolonization and rescue
>events are almost impossible;
>
>2) populations are small, such that collecting could represent a significant
>source of mortality;
>
>3) population represents a "desirable" species, such that collecting
mortality is
>consistent and persistent over time;
>
>4) population subject to wild stochastic variation and/or species in
question has
>low reproductive capacity.
>
>Based on these criteria, I think that in Indiana, there are exactly  three
>butterfly populations representing two species that are potentially
vulnerable to
>over collecting.  These are:
>
>_Speyeria idalia_ reduced to a single population in the state. Population
very
>isolated and occupies less than 200 acres.  Population fluctuates wildly,
>especially in response to recent fire history of the habitat.   Females
are very
>easily collected at milkweeds that line adjacent agricultural fields.  A
showy
>species that is almost impossible to obtain in much of the eastern US -
>collectors seek this one out.
>
>_Neonympha m. mitchellii_ reduced to about 15 populations in the World -
two in
>Indiana.  Populations all isolated, especially relative to observed female
>dispersal capacity which averages less than 50 meters.  Populations are
usually
>very small (based on MRR over two years at two "healthy" populations in
adjacent
>Michigan,  total adult brood size is between 200-300 per year.  The two
Indiana
>populations occupy habitats (fens) that are less than 3 acres in size.
Fecundity
>is low, with females likely laying about 50 eggs per year.  Females are
>especially easy to capture in this very sedentary species.  Desirability
is high,
>given the rarity of the species.
>
>There is a relatively large list of species that fit most of the criteria
above,
>but are not likely to be subjected to persistent collecting pressure
because they
>are "less desirable".  Very rare skippers, Incisalia, etc - we have plenty of
>small isolated populations of these types of animals, but collectors can
readily
>obtain specimens from many sites in adjacent states, and most collectors
simply
>don't care enough about these animals to be a threat.  Usually they  take
a short
>series for these species once in their lives.
>
>My bottom line is that I would never grant access to collectors for these
three
>vulnerable populations.  This does not mean that general inventory has not
been
>encouraged at these sites.  For example, Eric Metzler ran bucket-type kill
traps
>for moths in the heart of the _S. idalia_ population over the course of a
year.
>While he certainly killed a bunch of moths (thousands), the collecting
pressure
>was limited to a single growing season - hence not likely to impact any
unknown
>species that might otherwise be vulnerable to persistent collecting pressure.
>The potential positive impact to the site (better management based on
inventory)
>easily outweighed the potential risk to the site (in at least my mind).
>--
>John Shuey
>Director of Conservation Science
>Indiana Office of The Nature Conservancy
>
>Bruce Walsh wrote:
>
>> Some of the comments from the US Fish and Wildlife services contained in
>> the recent posting (by Neil) on the potential listing of the Sacramento
>> Mountains Checkerspot inspired me to think about the parameters underwhich
>> overcollecting can be a serious issue.
>>
>> I'm interested in the thoughts of others on the Leps-l about which
>> factors can make a population vulnerable  to overcollecting.  I'm
especially
>> interested in examples, either valid or cited by others, where
overcollecting
>> has caused significant harm to a population.
>>
>> I'm NOT trying to restart the collecting debate, so please let's start
>> the last year of the old millennium with a truce on this issue.  Rather, I
>> think that all sides will agree that there are certainly populations where
>> modest collecting has at best a trivial effects.  Likewise, I think all
>> sides will agree that there can be conditions underwhich very significant
>> collecting can have a serious impact.  What are these conditions?  All
>> thoughts are welcome.  You can send them to me or post them for the
amusement
>> of all of the list.
>>
>> Peace
>>
>> Bruce
>
>
>
>phone:  317-923-7547
>fax:  317-923-7582
>email:  Jshuey at tnc.org
>
>