Rare species

Stephen P. Rae srae at MUSCI.COM
Thu Jul 31 00:33:16 CDT 1997

After reviewing the thread on rarity and endangerment, I am submitting the
following for your information.

I also strongly endorse the suggestion by  Elaine Chittenden
<chitt at GNDS.MSU.EDU> to read the publication by  Deborah Raninowitz.  1981.
Seven forms of rarity. in The Biological Aspects of Rare Plant Conservation,
edited by Hugh Synge, Wiley & Sons Ltd., NY 558 pages.  This presentation
examines the components of rarity.  For an overview on R/E issues with
native plants in California (including concept and applciation), I refer
readers to The Conservation and Management of Rare and Endangered Plants,
edited by T. Elias in 1986 for the California Native Plant Society.  This
conference proceedings explores many facets of the issue and provides
background for understanding rarity and endangerment and how those terms may
apply in a political arena.  It also summarizes volunteer, professional, and
other noteworthy efforts in conservation and management.

At 12:20 PM 7/29/97 -0500, you wrote:
>At 09:19 AM 07-29-97 -0700, Dennis Paulson wrote:
>>How about an operational definition something like "present in such low
>>numbers that one could not be guaranteed of finding it on a visit to its
>>preferred habitat, using the best methods known to detect the species." I
>>study dragonfly biodiversity, and I can easily distinguish species in this
>>category. This definition can be used at any scale, from a species rare at
>>a given location to a species rare everywhere in its range. It would not
>>apply to a species fitting your first criterion of geographic or ecological
>>restriction, at least not where it is common; however, it would apply to
>>widespread species at very low density. Surely low density is one of the
>>most significant criteria for rarity, as it relates directly to the
>>stochastic issues of sex ratios and mate finding.
>I disagree.  From a conservation perspective (which, after all, is the arena
>in which rarity is most discussed), a widespread low-density species may
>have a more secure future, and be in better shape in terms of genetic
>diversity, than a species restricted to a few places or to a specific
>habitat that (originally or through human intervention) only occupies some
>small percentage of the world's surface.  The danger of putting all one's
>eggs in a single basket.

Perhaps the concept of rarity is being confused with that of endangerment.
Rarity deals with numbers and distributions, while endangerment is a
subjective measure of the expectation of survival over time.  In California
since 1978 we have dealt with state, federal, and private definitions of
rare, endangered, and threatened plant and animal species.  In spite of
vigorous discussion, disagreement remains over how the different definitions

The primary issue for biologists should be to accurately determine the
distribution and numbers of a species.  In doing so, we also need to look at
life history and evaluate those critical points where the survival of the
species may be more vulnerable.  And, the key component of the habitat and
the critical link in the life history may not be the same throughout the
distribution of a species.  Only then can we give our assessments to the
'suits' for the political discussion - ie, how can land use management be
translated into species conservation or protection?
>>There has been quite a bit of discussion about rarity and political
>>boundaries, about the value of considering species that are rare in a
>>political unit, e. g., rare in an American state even though common
>>elsewhere in the U. S., worthy of special concern. Most state wildlife
>>agencies and conservation groups seem to consider this status very
>>seriously. Rarity at any scale, even rarity in a particular urban area of a
>>species common in the nearby countryside, seems to endow a species with
>>special status, for better or worse, and I suspect the concept of rarity
>>will remain rather subjective and parochial.

In defense of the parochial view of an agency in determining rarity and
endangerment as it occurswithin their jurisdiction, please keep in mind that
the agency has no jurisdiction outside its borders.  Therefore, protection
measures must be predicated on the authority of the agency to enforce them.
Obviously, if a species is widespread and in good shape outside our borders,
we may be tempted to help it a little less in comparison with a similarly
distributed species within our area that is really in bad shape outside.
(this is an awkward sentence, I hope the reasoning is clear).  While I am
not apologizing for agency myopia, I suggest that it is basedon political
and legal realities.
>The argument I've heard advanced for state rarity lists goes something like
>this: such species on such lists are often outliers or peripheral
>populations on such species, and it is often in these somewhat isolated
>populations that "interesting" evolutionary things occur.  Thus, to preserve
>the total diversity of a species, such semi-isolated populations may be more
>important than more centrist populations.  I'm not sure there's a lot of
>data to back this view up, and I'm not particularly enthused over
>geographically delimited lists of imperiled species.

I once heard Jim Reveal expound about this concept as it applied to
Eriogonum in and around the Lahontan Basin.  In any case, such an argument
doesn't carry as much weight as the one about "there isn't any more of this
species in our area so we better get on the ball and do something about the
stuff we have left!  And, don't rely on our neighbors to protect theirs
because they don't operate in the same way that we do!"  When I administered
the rare plant program for California (1978-1982), this reasoning surfaced
at various times as we listed 129 taxa of rare and endangered plants.
>On the other hand, given the numerous threats confronting natural
>populations, its probably better to err on the side of bestowing coveted
>"rare" status too liberally, if that's what it takes to save them.   I'm
>reminded that the much-beloved  Hawaiian naturalist and
>conservation-evangelisr Otto Degener once suggested that ALL  endemic
>Hawaiian species be red-listed as Endangered, and only moved to a blue-list
>or safe-list once data had shown such status to be unwarranted.
Once again, we shouldn't mix 'rarity' with 'endangerment.'   While a
biologist can make a convincing argument about the rarity of the species,
few can do a credible job about the endangerment of the same species.
Postulating endangerment calls for land use management evaluations, review
of market factors and other social issues, and a feeling for the political
arena (in addition to looking at the biological problems that rarity may
bestow on a species).  Most biological publications evaluating endangerment
that I have reviewed have suffered from reliance on anecdotal evidence and a
superficial understanding of land use management practices (including legal
restrictions and rights).  We must continue to improve our endangerment
evaluations because they will end up being debated in a political arena and
dissected by lawyers and politicians.  We need to anticipate their questions
and convey our biological concerns in a context they understand.
>Thomas G. Lammers
>Classification, Nomenclature, Phylogeny and Biogeography
>of the Campanulaceae, s. lat.
>Department of Botany
>Field Museum of Natural History
>Roosevelt Road at Lake Shore Drive
>Chicago, Illinois 60605-2496 USA
>e-mail:     lammers at fmppr.fmnh.org
>voice mail: 312-922-9410 ext. 317
>"Science is not a sacred cow.  Science is a horse.
>  Don't worship it.  Feed it."
>                          --Aubrey Eben

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