Papilio machaon

[kiwi]

Has there been any proposed re-introductions of Papilio machaon anywhere other than the Norfolk broads? I'm sure it wouldn't be too difficult to plant some milk parsley until there is a large population and then release the butterflies into the area. This could be done in various places throughout the country, and as the milk parsley extends its range, so would the swallowtails.

[James M]

I haven't heard of any recent attempts, the last one I think was one at Wicken Fen in the 90's but I think they died out as a result of a run of dry summers.

[harasseddad]

Actually it's incredibly hard to plant Milk Parsley and get it to grow. The problem is that the plant requires water levels to be just right, and maintaining those levels requires co-operation from adjoining land-owners. This is usually controlled by regional drainage boards, which set the level at which your water should be kept. Each landowner has the right to transfer excess water to adjoining land, who pass it on until it reaches a river or drain. It's no co-incidence that the strongholds of the swallowtail in the broads are mostly reserves which adjoin rivers - allowing some degree of independent control. It still gets tricky in dry summers and wet winters though.

Wicken Fen could never get the water right for Milk Parsley, and the swallowtails consequently died out. (If your local landowners are arable farmers, as they were in Cambridgeshire, they want water levels much lower than is accepted by seasonal cattle grazers in Norfolk.)

Hopefully the great fen project will allow greater greater control of water levels, and more sucess in future.

[Neil Jones]

introducing butterflies rarely succeeds. The answers here show some of the problem. One of the other problems is that for a population to survive it needs
a large area of landscape. This is probably why the went from Wicken Fen.
There is evidence that the swallowtails there developed thinner less powerfully muscled thoraxes for example because flying away was selected against. The colony was isolated and not part of a metapopulation like in Norfolk.