anise swallowtail & purplish copper

[Neil Jones]

In article <00ad01c09bcf$225f9980$4ddcc2cf at nysven>
           cguppy at quesnelbc.com "Cris Guppy or Aud Fischer" writes:

> Neil,
> 
> Given that you live in Britain, and obvious know much more than I about
> butterflies there, you are likely to be more correct than I. The reference
> on which I based my statement is:
> 
> Thomas, J.A. 1984. Conservation of butterflies in temperate countries: Past
> efforts and lessons for the future. Pp. 333-53 in The Biology of
> Butterflies. Symposium of the Royal Entomological Society of London Number
> 11, edited by R.I. Vane-Wright and P.R. Ackery. London: Academic Press. xxiv
> + 429 pp.
> 
> I would welcome suggestions of more recent references that I should consult
> for a better understanding of the success/failure of introduction attempts.
> 
> Cris Guppy.

Thanks for that Cris. I have my own copy of the book to hand.
Jeremy Thomas is one of our best known experts here.
He does mention a list of "introductions known to the author".
He also mentions some of the species where it has succeeded.
This can at first glance give the impression that introductions work.

There are some problems with drawing the conclusion you have from this paper
which is a general one on conservation not just on releases

1 He happens to list some of the species which are
exceptions to the general rule such as Strymondia pruni The Black Hairstreak.
This species seems to take very well but is not typical.

2. He doesn't give any weight to the failures.

3. His list of successes includes some where support releasing has taken
place. 

The other problem I think is that the paper is rather old and research 
has moved on. I don't think Jeremy Thomas would say the same things if
he were writing it today. For example the table on minimum viable colony areas
is perhaps not really so valid today in the light of modern metapopulation theory.
I would think that he would certainly be very aware of this, not least
because his younger brother, Chris Thomas, is one of the leading researchers
in the field of butterfly metapopulation study.

The section on genetic deterioration is another example. There was a paper
on the Glanville Fritillary (Mellitea cinxia) in Nature written by 
some of the experts from Helsinki  few years ago which might have led him to
different conclusions.

I don't deny that some introductions fail because of habitat changes, but the
truth is that they can fail even when things seem to be done perfectly.
In one failed case I know the turf from the original site was actually
moved to the new site before the butterflies were introduced!

Ecology is complicated. This makes the conservation of butterflies a 
complicated subject. (Perhaps that is why I like it. What is the point
of studying something simple!)

For a better source of information on the success rates might be
Oates M. R. and Warren M. S. 1190 a Review of Butterfly introductions
in Britain and Ireland. Published by the Nature Conservancy Council.

Or Martin Warren's paper in the Ecology of Butterflies in Britain
edited by Roger L.H. Dennis. published in 1992 by Oxford University Press
This presents the main data. If you look at the results. Out of 323
releases there were only 12 introductions which had lasted 10 years or
over. 9 of these were for just three species and I know from the
author that the 3 of these have all subsequently died out (All the same
species and all the over ten year survivals for that species.)


-- 
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


 
 ------------------------------------------------------------ 

   For subscription and related information about LEPS-L visit:

   http://www.peabody.yale.edu/other/lepsl