New sightings of short-haired bumblebees show a scheme to reintroduce the vanished species to the UK is proving successful, conservationists have said.
Three short-haired bumblebee workers were spotted at the RSPB's Dungeness nature reserve in Kent, where the reintroduction scheme is taking place, on four consecutive days.
The short-haired bumblebee vanished from the UK in 1988, having suffered declines over the previous 60 years as its habitat was lost, and was officially declared extinct in 2000.
A scheme to reintroduce the species has seen experts collecting short-haired bumblebee queens from Sweden, where they are found in good numbers, and releasing them at the Dungeness reserve each year since 2012.
There have now been consistent sightings of workers bees over the last three years, showing the queens have successfully nested and produced young and indicating the bees are finding enough food to build colonies, experts said.
The Bumblebee Conservation Trust's short-haired bumblebee project manager Dr Nikki Gammans said: "This is a thrilling discovery and shows that conservation for bumblebees really can work.
"Populations of at least three other rare bumblebees are now found in locations across the release zone not recorded in for over 10 years and their abundance is increasing across south Kent and East Sussex."
The scheme, by the Bumblebee Conservation Trust, the RSPB, Natural England and Hymettus, is backed by local farmers and landowners in the Dungeness and Romney Marsh areas managing 1,000 hectares (2,500 acres) of flower-rich habitats for bees.
As well as the short-haired bumblebees, other rare bumblebee species and a range of pollinators are being supported by the wildflower-rich habitats which provide them with food.