Species recovery programme

Wart-biter bush cricket Our captive breeding and release efforts have concentrated on rare insects, birds and mammals, and we collaborate closely with other breeding centres, field scientists and land managers to link breeding initiatives with field management.

In 1991, British populations of the field cricket were reduced to a single surviving colony, and the handsome wart-biter bush cricket was confined to a handful of isolated sites in Kent and Dorset.

Many species that depend on hedgerows, like the dormouse, are suffering populaton declines. A similar situation prevailed for the barberry carpet moth, which was only known to survive at three sites in 1995.

Captive breeding programmes were therefore established for the crickets at ZSL London Zoo and the moths at ZSL Whipsnade Zoo. Attention was given to obtaining founder populations from the wild, without damaging existing populations, and maintaining captive over-wintering stocks to accelerate breeding output.

Releasing field crickets into the wild The outcome of these efforts has been three new wild colonies of field crickets, with the largest (and first) release population growing to some four times the original parent colony. In all, over 13,000 individuals have been released, rebuilding populations in West Sussex and Hampshire.

For the wart-biter cricket, over 600 late instar animals have been released in Kent, where there are now two thriving colonies, and for the barberry carpet moth, food plants have been planted around Whipsnade and over 6,000 final instar larvae have been reared for field release.

We have also bred two vertebrate species for release: dormice and corncrakes. Zoos and private breeders combined forces to breed hazel (common) dormice to re-establish populations of this charismatic species in the northern edge of its range, and since 1996 ZSL has contributed over 30 individuals.

The corncrake project aims to re-establish corncrakes in the Cambridgeshire fenlands, where they previously occurred. In 2002 a founder population of 24 birds was established at Whipsnade, and more than 100 captive bred birds from this stock have been released into the wild.

Excitingly, in 2004 a wild female corncrake was seen in the wild with a captive-bred male – along with three chicks! This proof of success is very encouraging. The project will run for at least 5 years, with careful monitoring to determine whether captive breeding and release can be an effective conservation tool for this migratory species of bird.