The small tortoiseshell (Aglais urticae) is in a very sad decline. Whereas once it was one of our most common and best-loved garden butterflies, it is now in danger of following its cousin the large tortoiseshell (Nymphalis polychloros) into extinction in the UK at least. Hang on a bit, did I say extinction?
The thylacine was once described as being the healthiest extinct animal alive. The same could probably be said about the British large tortoiseshell. It has bred at least once in South Devon in recent years, and on 14th March one was seen and photographed in Central Park, Plymouth. This is not bad for an animal which has supposedly been extinct in the UK for the last 50 years.
A week or so ago another extremely rare visitor, the long-tailed blue (Lampides boeticus) was seen in Hampshire. These remarkably widespread butterflies are found around much of the globe and are known to be great travellers. Whereas many Nymphalid butterflies are known for migrating (red admirals and painted ladies for example) I believe that the tortoiseshell species are far more sedentary. Are the large tortoiseshells which are now seen every year in the southern part of the UK, vagrants like the long-tailed blue or are they the rump of the indigenous population? In recent years we have seen how pine martens and polecats, two species which were popularly believed to have been hunted to extinction over a century ago, not only are re-colonising their former haunts, but actually never left. Could the same be the case with the large tortoiseshell?
Or could they be the result of unofficial re-introduction programmes? If so, bravo to everybody who is responsible. Whilst on the subject of unofficial re-introductions, the latest edition of the Devon Butterfly Conservation Newsletter, from which I got hold of the Plymouth sightings, also describes – in passing – the sighting of a swallowtail in South Yorkshire in the early ‘60s. My friend and colleague Richard Freeman, who shows no great interest in butterflies, (they are not big enough, dangerous enough or gothic enough) tells me that he has seen them in both Leeds and Nuneaton. Are such sightings the results of another artificial introduction?
During my researches into the history of British butterflies it turns out that the swallowtails that used to live in the Thames Valley behave completely differently to those last remnants of Papilio maechon britannicus which are found to this day in East Anglia. They weren’t marsh dwellers, and they didn’t have such a specialised food plant. Is it possible that because:
a. we live in a society which is becoming increasingly urbanised and divorced from the natural world, and
b. because the concept that British swallowtails only live in East Anglian marshes is so ingrained in us that we don’t both to look for them anywhere else, that there might actually be a few isolated pockets of non marsh-dwelling swallowtail in the Midlands and north of England?
I think, now, you can see why I have been writing a cryptozoological tome on British butterflies for the last five years.