One of England's rarest birds of prey, the hen harrier, is facing extinction, the Royal Society for the Protection of Birds (RSPB) has warned.
All of England's hen harriers are in the Forest of Bowland
Conservationists are calling on members of the public to report any sightings of the bird so they can monitor the dwindling population.
There has been a "disastrous decline" in the number of hen harriers.
There were 22 breeding pairs in 2003 in England, but only eight last year - all in the Forest of Bowland, Lancashire.
It is feared that that if the decline continues, the future of the bird, which is a protected species, could be in doubt.
Hen harriers breed on upland heather moorlands and during the winter move to lowland farmland, heathland, coastal marshes and fenland.
The males are pale grey while the females and young are brown.
Peter Wilson, RSPB Birds of Bowland project manager, said the situation was "of great concern".
He said: "We are talking about relatively low numbers already, so when there is a decline of over 50% from one year to the next, it is very worrying."
The RSPB is now wing-tagging young hen harriers so they can monitor where they go during the winter and how well they survive.
A major cause for concern is that the hen harrier is disliked by many estate owners because it eats red grouse chicks, affecting the number of grouse
available to shoot during the autumn.
The RSPB claims the hen harrier is the "most intensively persecuted" bird of prey in the UK.
In 2002, numbers were so low that English Nature set up a Hen Harrier Recovery Project, but despite a boost in numbers in 2003, the population is falling again
Hen harriers are a protected species
Richard Saunders, English Nature's project officer, said: "We have had reports of birds being shot, and sightings of birds with shotgun
damage to the wings. Someone is definitely targeting the hen harrier.
"Now we only have breeding at one site in England. There are still reasonable numbers breeding in Scotland, but in terms of British birds the hen harrier is
as rare as you get."
The Association of Chief Police Officers launched Operation Artemis to enforce the Wildlife and Countryside Act, under which anyone who destroys eggs or kills endangered birds faces a £5,000 fine and
six months in jail.