The population of a species of wading bird in Guernsey has fallen by 99% over the past 20 years, according to an environmental and heritage group.
There were about 100 purple sandpipers at Vazon Bay 20 years ago but in 2013 that number had dropped to just one.
Environmental experts from La Societe Guernesiaise say dogs are disturbing the birds' feeding ground stopping them from returning to the island.
The society's Jamie Hooper said it was hard to stop people walking dogs there.
He said: "About 20 years ago if you went down the beach in the winter you would have the beach to yourself, there wasn't the use of beaches we see now.
"Our most important beach for waders has now a reputation of being the dog beach so everyone walks their dogs here and that disturbance is having a cumulative effect and the birds are going elsewhere."
Mr Hooper said almost all of the waders seen in Guernsey were in decline and the purple sandpiper, while not common to Guernsey, had dropped by 99%.