environmental enhancement again

[Neil Jones]

On 16 Jan, in article <002501c19eb1$192d8c60$2cc8b8a1 at net>
     isheldon at telusplanet.net "Ian Sheldon" wrote:

> One of the European examples Norbert may be making reference to is the
> British Large Blue (Maculinea arion). I was living in England at the time of
> the extinction of this beautiful butterfly, and the cause of its demise was
> discovered too late. For those who dont know the story of England's possibly
> most famous butterfly extinction, its well worth checking out. Changes in
> grasscutting practices over several decades led to longer grasses, which
> resulted in the demise of the red ant species on which the Large Blue is
> dependent to complete its larval phase. Not only is it an excellent example
> of the dependence of a species on human-induced disturbance, but an
> ecological marvel as well.

To clarify matters it isn't grasscutting practices that are the key but
_grazing_levels_. The butterfly has a relationship with the ant Myrmica 
sabuleti. It actually is taken down into the ant's nest where it consumes
a diet of ant larvae. The key fact for M. sabuleti survival is temperature.
Longer grass meant cooler ground temperatures which the ant could not survive.

> Perhaps the species had been dependent on
> artificial grazing/harvesting for centuries. Lessons learned from this
> example may help the continental European species in the genus from further
> dwindling. And an example of horrendous damage I agree! Unfortunately I am
> not up to date on the proposed reintroduction of a large blue to the old
> sites of M. arion.

The ecology of this species had been worked out by the time it became extinct.
The population was just too small. The last generation were 22 adults the 
decendant of a single female of only 5 adults to emerge in the previous year.

It was first put back from Swedish stock onto the last site which is known
as "Site X". It is still surviving there and has been moved onto
several other sites. However, even with all the expertese that has been
developed some of the introductions have failed. In general butterfly 
introductions are very very difficult to get to work.


-- 
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


 
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