The brightly coloured Marsh Fritillary butterfly is capable of population explosions which can lead to a scarcity of food and then a severe reduction in numbers.

This is the precarious situation at Strawberry Banks, near Stroud, where the protected species has established its only colony in the Cotswolds Area of Outstanding Natural Beauty (AONB) on a site of special scientific interest (SSSI).

Landowners in the area are being urged to help ensure the butterflys' future by forming a network of local 'back up' sites capable of supporting them should the population at Strawberry Banks crash. Without these "holding" populations the creatures which were once widespread in Britain and Europe may not survive.

During the last century their numbers have declined rapidly. The volatile fluctuations take place in close knit colonies which are formed on discreet patches of habitat. Adults rarely fly more than 50-100m but a small proportion seem to disperse further.

The Cotswolds Conservation Board have teamed up with an impressive range of organisations including English Nature, DEFRA, Butterfly Conservation and The National Trust to help manage them.

The area of land they inhabit is managed by the Gloucestershire Wildlife Trust Nature Reserve.

Jenny Phelps, grasslands officer for the Cotswolds Conservation Board, said:

"We want to demonstrate how all the partner organisations involved are working together and the way that landowners can protect limestone grassland and the survival of this rare butterfly. This can be achieved without compromising the landowners' other interests and objectives."

The project is part of a larger five-year scheme from the Cotswold Conservation Board called "Caring for the Cotswolds."

It is supported by a £1.4 million grant from the Heritage Lottery Fund and covers three areas - limestone grasslands, drystone walling and local distinctiveness.