Rare or Threatened and relative abundance status

Eric or Pat Metzler spruance at infinet.com
Wed Jul 25 09:17:59 EDT 2001


Dear Vratislav Richard Eugene Maria John Baptist

Your questions are excellent, and deserve full exploration by us and all
field bioloists.

I offer one caveat to Michael Gochfeld's highly informative and very
accurate answer.  He's absolutely correct about the definitions.  In many
cases the distinctions drawn by Goldfeld do not exist.  There are two views,
the academic, and the view practiced in the field.  The views practiced in
the field, unfortunately, blur the distinctions he offers.

In the vernacular, the average person, and many learned persons who
interpret the laws of threatened and endangered, equate rare with
endangered.  In fact, many classifications, i.e. The Nature Conservancy's
classifications, and some regulations use the phrase "rare or
threatened/endangered."  Therefore, when we field persons use the word
"rare" to mean "Not usually seen at any time and place.  Fewer than five
times in
 a season and then only one individual at a time." sensu Goldfeld, the
regulators assume the species is threatened or endangered.  By their
official definitions, such is the case.  Which means, the distinctions drawn
by Goldfeld: "The final answer: I don't think there is much of a
relationship betweenthe conservation status and the relative abundance." is
interpreted just the opposite for most other people.

The distinction I draw is especially important when a person is talking
about organisms that are under-sampled for any number or reasons including
the inadequacy of the sampling methods (i.e. using black lights for day
flying moths).  A declaration of an abundant species of moth, which is
poorly represented in collections, as being rare could result in the moth
being listed as endangered.  In Ohio, such a scenerio almost happened when
the very learned Roy Rings innocently prepared a list of species, that are
rare in collections, for a project on reprentation of specimens in
collections in Ohio, only to find the list used by the USFWS as a basis for
declaring the same species as endangered.  It was very embarrassing for Roy
to have to discredit his own list just because someone else misused it.

The distinction I draw happened in Michigan when Mo Nielsen innocently
provided a listing of species rarely seen in Michigan only to have his list
become the central list of endangered species including ephemeral species
that do not annually reside in Michigan.  It has taken about 10 years to
straghten out the missunderstanding in Michigan.  Inexcusibly, the burden
was on Mo to explain why his listing was wrong, even though he carefully
documented all of his assumptions.

In both cases, and I'm sure there are others, the confusion came because of
the official definition of "rare = threatened/endangered."

For these reasons, I no longer use the word "rare," and I encourage others
to drop this word from their vocabulary.  The word "rare" is so often
misinterpreted that I feel it has no precision, no matter the definition.  I
now use the phrase "infrequently seen," for which there is not official
definition, legal or otherwise, thus I am allowed to create my own
definition.

When you use the word "rare" you are subject to some other person's
definition.  And it doesn't matter how careful you are to create your own
definition.

I hope these case histories help answer your questions.

The Lepidopterists' Society's annual meeting is in Corvalis, Oregon end of
this week, and I hope that many of you will be there.

Cheers to all from Columbus, Ohio where it has been punishingly hot, but now
it is raining.

Eric Metzler

"Michael Gochfeld" <gochfeld at EOHSI.RUTGERS.EDU> wrote in message
news:1010724201202.ZM4238 at Gochfeld...
> In response to the following question
>
> I would like to know how to categorize abundance of the insect.
>
> Rare or Endangered?
>
>  Is there any link between category like:
>  Very common - Common - Very abundant - Abundant - Rare - Very rare -
>  Sporadic
>  and category like:
>  Common - Vulnerable  - Threatened - Endangered - Critically
> Endangered???
>
> The status  "special concern", "vulnerable", etc are conservation status
> categories which have legal or quasi-legal status when it comes to
> conservation and management.  A species may be classified as endangered
> even if it is locally common, if there are only one or two populations
> in a state.
>
> The other categories: abundance, etc, can be considered categories of
> relative abundance.  We provided a semi-quantitative definition in
> BUTTERFLIES OF NEW JERSEY (p36).
> "superabundant" one may find more than 500 individuals in a given place,
> or a 4JC (fourth of July count) total greater than 2,000"
> This is all relative:  2000 Cabbage White (Pieris rapae) may not
> seemlike much, while 2000 swallowtails would generally be accepted as
> superabundant.
>
> Abundant: more than 20 at the right time or place or more than 500 on a
> 4JC.
>
> Common: 5-20 in a day and more than 100 on a 4JC
>
> Fairly common   1-4 individuals in a day and more than 10 on a 4JC
>
> Uncommon  1-4 individuals several times in a season, but not daily
>
> Occasionally common.  5-20 individuals in a day but only a few times in
> a season.
>
> Locally common: "a species that is uncommon, rare or absent in most
> habitats or locality, but common in its preferred habitat" (or in a few
> localities).
>
> Rare.  Not usually seen at any time and place.  Fewer than five times in
> a season and then only one individual at a time.
>
> Irruptive: usually rare or absent, but may occasionally become common or
> abundant.
>
> We didn't incude vagrant, accidental, or other terms to describe species
> that can NEVER be expected but somehow turn up far out of range.
>
> In reading these definitions written more than a decade ago, I wonder
> whether they should be taken seriously or whether they can be applied
> across species.  For instance 10 Harvesters (Feniseca) would be
> considered abundant in most locations.
>
> The final answer: I don't think there is much of a relationship
> betweenthe conservation status and the relative abundance.
> I hope that is helpful.  M. Gochfeld
>
>
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