During the past 15 years at least nine species of native plants and animals have disappeared from the wild in Britain. Scores of others are on the brink of extinction and some could slip over the edge in the coming year.
Next month, in line with commitments accepted at the Earth Summit last year in Rio de Janeiro, the Government will unveil a national biodiversity action plan, the first attempt at an overall strategy for conserving Britain's flora and fauna.
Some plants and animals are beyond recovery but others, surviving in some cases in a single site, can still be saved. For a few species that have disappeared in the wild only recently, reintroduction may be possible.
More than 1,240 plants, mammals, birds, insects, fish and amphibians in Britain are estimated to be at risk, and several hundred are sufficiently endangered to need legal protection. Extinction is relatively uncommon.
Margaret Palmer, a conservation specialist who is compiling a national species data base, tentatively identified nine losses during the past 15 years. A verdict of "missing, presumed extinct" is pronounced when a species has not been seen for at least three years.
The first to go was the large blue butterfly in 1979, followed in the early 1980s by the viper's-bugloss moth, the Ivell's sea anemone and the stinking hawks-beard, a cousin of the dandelion. There has been no sighting of the lagoon sandworm since 1985 and the last known nest of the meadow wood ant has lain empty since 1988. The red-backed shrike, a small hawk, made its last appearance in 1989; and nothing has been seen since 1991 of the Essex emerald moth and the greater mouse-eared bat, the first native mammal to become extinct since the wolf in 1745.
"Some of these may come back on their own," Ms Palmer said. "Plants are notoriously difficult to be certain about because their seeds can lie dormant in the soil for years. The starfruit plant, for example, was thought to be extinct several years ago but reappeared when a pond where it had grown was dredged of excess vegetation."
Recreating habitats is one approach to recovery, but may not always be practical. Scientists often do not know what is needed to save a flower, bird or insect from extinction because they have no idea why it has declined. In some cases rescue would be unjustifiably costly, particularly if the species were abundant in other countries.
Three years ago English Nature, the Government's wildlife adviser, launched its species recovery programme, naming about 20 plants and animals in need of emergency treatment. Those on the list are either on the edge of extinction in the wild or have already gone but could be re-introduced using imported stock and seeds stored in seed banks.
One of the most promising experiments involves the large blue butterfly (Maculinea arion), which scientists are trying to re-establish on six sites in Cornwall, Devon, Somerset and Gloucestershire using larvae imported from Sweden. Egg-laying and breeding have occurred at two of the sites and the butterflies are extending their range.
Research has identified two key requirements for the butterfly: large patches of wild thyme in which the females lay their eggs, and a healthy population of a particular species of red ant, without which the butterfly cannot complete its life cycle. Both elements have been hit by intensive agriculture.
Scientists know rather less about the lagoon sandworm (Armandia cirrhosa), which has never been known to exist at more than one site, a lagoon in Hampshire. In 1985 the number of worms there was put at 5 million, but when scientists surveyed the site in 1991, with the idea of transplanting some elsewhere, they found none.
In the mid-1980s Hampshire County Council had ceased draining the lagoon in winter, and it was thought this change might have caused the sandworms to disappear.
High on English Nature's rescue list is a group of plants and insects clinging to survival in the wild. These include the Lady's Slipper orchid (Cypripedium calceolus), confined to one locality in Yorkshire; the strapwort (Corrigiola litoralis), found only in a coastal lagoon at Slapton Ley, in Devon; the New Forest cicada (Cicadetta montana), recorded at only one place in the Hampshire forest; and the reddish buff moth (Acosmetia caliginosa), which survives on a patch of heathland on the Isle of Wight.
Strapwort (Corrigiola litoralis): exists only at Slapton Ley in Devon, a coastal lagoon. Grows on exposed shores in summer. Drainage of lagoon is being improved and cattle reintroduced to keep down competing vegetation.
Lady's Slipper orchid (Cypripedium calceolus): one site in Yorkshire kept secret to deter collectors. Botanists at Kew are trying to grow orchids from seed taken from the native flower and transplant them to the wild, without success.
Reddish buff moth (Acosmetia caliginosa): survives on one patch of heathland on the Isle of Wight. The plan is to introduce the moth to two other sites on the island by creating habitats suitable for its main food, the saw-wort plant. Search for other surviving colonies has drawn a blank.
New Forest cicada (Cicadetta montana): one site left. Reason for decline not clear. Appears to like sunlit, open glades and may have been affected by encroaching scrub and bracken. Behaviour being monitored with aim of re-introducing insect to former sites.
Large blue butterfly (Maculinea arion): this and the following are examples of species that have become extinct in Britain (though attempts are being made to reintroduce some). The large blue butterfly's last known site was in Devon and it became extinct in 1979. Swedish imports are being introduced to six sites based on research showing the butterfly's need for wild thyme and its close association with a species of ant.
Greater mouse-eared bat (Myotis myotis): not seen since 1991. Presumed extinct in Britain. First native mammal to be lost since wolf in 1745. Roosts in caves in summer and needs other bats for warmth. Global warming might create conditions for return.
Red-backed shrike (Lanius collurio): last pair seen in Thetford forest, Norfolk, in 1988. Single male returned in 1989 but could not find a mate. Now presumed extinct in Britain. In decline throughout northwest Europe since last century. Cause unknown.
Stinking hawks-beard (Crepis foetida): thistle of dandelion family that likes coastal conditions. Last wild plant seen at Dungeness, Kent, in early 1980s. Experimental plots at Dungeness have been sown with seed stored at Kew. Too soon to say if it can be restored to wild.
