Extinction of Mitchell's Satyr by collectors
jshuey at tnc.org
Wed May 17 10:21:39 EDT 2000
Bob Kriegel asks a hard question below. I'll provide as much information as I
can, and then let you decide. If you want the short answer, my bottom line is
that I don't know.
kriegelr at PILOT.MSU.EDU wrote:
> I know that there are list participants out there who have more information
> on the truth-or-urban-legend of the statement below.
> > It is widely believed that Mitchell's Satyr was eliminated from its last
> > known New Jersey location by collecting.
The evidence that led people (and by people I mean Dale Schwietzer, at the time
a TNC employee) to believe that collecting played a role is as follows.
1. Dale visited one of the three sites himself on perhaps the last year it was
recorded from the fen. He never saw a mitchell's satyr at the site, but did
find a glassine envelope laying on the trail, indicating that a butterfly
collector had proceeded him to the site.
2. The collector (some New York City MD., now deceased) that really knew about
two, possibly three sites really did collect the hell out of the population.
One needs only visit the American Museum of Natural History to see the several
drawers of specimens collected from these small populations in just a few short
years. Several hundred specimens in total. The data on the specimens are
purposefully cryptic, such that you can't really tell where they were collected
from (hence the confusion of how many sites there really were). The other
thing you notice when you look at the data, is that this guy collected the site
3-4 times a week during the 2-week flight period. And when you look at the
quality of specimens, you get the impression that he bagged every specimen he
encountered (there are lots of complete rags in the series). If ever there
was a collector who typified the stereotype bad stamp collector mentality, this
guy was probably it.
So that was the evidence at the time - circumstantial to say the least.
Confusing the issue is the condition of the two know sites (based on
conversations I've had with New Jersey Heritage staff). Both fens are highly
degraded, suffering from invasion of red maple (either fire or beaver likely
played a role in maintaining the open nature of the habitat). This degradation
was well underway when Mitchell's satyr was declining. Today, these fens don't
seem likely to be able to support the butterfly, based on habitat size alone
(unless someone has been managing them since I had these discussions a few
years back). Hence, it seems likely that habitat dynamics alone could have
been responsible for the ultimate decline of the butterfly.
> Other than a presumed increase in collecting pressure, what evidence is
> there that the last population was eliminated by collectors?
Now I want to confuse the issue further, based on some recent work on
Mitchell's satyr in SW Michigan.
A). Based on two years of mark-release-recapture data at two sites, here is
what we know about population structure relative to these issues.
A) Populations at these sites were fairly small, somewhere between 200-300
B) With daily effort, we were able to capture around 50% of the population
C) Fecundity is apparently pretty low, with most females laying 5-10 eggs per
day over about a five to seven day period. There is no initial large batch of
eggs produced from what we can tell.
D) vagility is very low - most females move less than 50 meters during their
So, if you factor in this information, it does seem likely that you could, over
the coarse of a several year effort, cause a serious decline in small
populations of this species. For example, if we had been killing females
instead of writing numbers on their tushes, I bet we would have knocked our
study populations down by about 50% over the two years.
But now, I'll confuse the issue even further. Two sites in Michigan have take
the brunt of collecting over the decades, Wakelee Bog and Liberty Fen (both now
partially owned and managed by the Conservancy). Both support very vigorous
populations. In the case of Liberty, the population did decline noticeably in
the mid 80's, but has now recovered. At Wakelee, the population has always
seemed very robust (likely much larger than the populations were we did the MRR
work). This despite a long and glorious history of collectors driving from all
over the country to collect these two sites.
Now and interesting aside: the southern subspecies, Neonympha mitchellii
francisci, was emergency listed because of the threat from collectors. This
species was described by Parshall and Krall, two collectors who are of the
classic long series mind set (as in the longer the better). Remember, Krall
was one of the three collectors later convicted for violating several federal
laws regarding endangered species and collecting in protected areas. Hence,
when North Carolina heritage staff visited the only know population site (type
locality) and could not find it, they naturally assumed that it had been
collected out of existence. (keep in mind that heritage staff have long been
under the influence of Dale Schwietzer's opinions, and hence were already aware
that New Jersey populations had been "collected to extinction"). So the story
started (as part of the emergency listing) and persisted (I still see it
kicked around, most disturbingly in the recovery plan for this subspecies) that
North Carolina populations were collected to extinction.
As it turns out, this was all a big screw-up. The map to the type locality
(provided by the authors) was bogus. Of course the butterfly population at the
site was "extinct". Once folks finally figured out where the type locality
really was, they found the butterfly. But the story still persists as urban
legend. As it turns out, the exact spot where the butterfly was originally
discovered has indeed gone temporarily extinct (the habitat has shrubbed
over). But the real population persists in the impact range of Fort Bragg,
apparently healthy and thriving in the habitat maintained by a steady
procession of bomb-induced wild fires.
The repercussions of all of this persist to this day. A small set of
populations have recently been discovered in another east-coast state. The
perceived threat of collectors is so great that almost nothing is known in the
general conservation community about the sites (for example, just yesterday I
was talking to the guy working on Mitchell's satyr at Ft. Bragg, he heard that
the new populations were in the mountains, I had heard that they were in the
piedmont - and we are both heavily involved in conserving this species!)
> Folks, this one is worth airing out. This extinction event has been
> referred to in Nature Conservancy literature and in National Geographic
> magazine. It is the most widely cited case in North America for the
> extinction of a butterfly population by collectors. I have heard strong
> opinions on both sides of the argument about this event. What I have not
> heard is evidence!
> Bob Kriegel
The bottom line is this, as a TNC employee, it almost killed me when I saw us
printing this "factoid" in our national publication (this goes out to over a
million members). National Geographic hits even more folks - and both are
supposed to be pretty authoritative. I think that the evidence is way to shaky
to say with certainty that the story is fact.
On the other hand, if ever there was a convergence of factors ranging from a
susceptible species to a collector who could actually put the hurt on a
population, New Jersey is it.
So, years into pondering all the evidence I've come to the conclusion that
there really isn't a clean answer to this issue.
Director of Conservation Science
Indiana Office of The Nature Conservancy
email: Jshuey at tnc.org
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