The RSPB says man is driving the hen harrier to extinction
Cyclists, walkers and tourists are being urged to help save one of England's most endangered bird of prey by reporting sightings to a hotline.
Years of nest destruction and illegal killings mean just six breeding pairs of hen harriers were left in England last year, says birds charity the RSPB.
Any confirmed sightings will help to target the work of nest monitors.
They hope to work with land managers to mount a 24-hour guard on nesting sites. The hotline number is 0845 4600121.
For the past few weeks, Royal Society for the Protection of Birds field workers and volunteers have been trying to find and record every hen harrier in England.
Numbers have dwindled despite there being habitat for at least 200 pairs, the charity says.
Senior conservation scientist Mark Eaton said the survey would take a lot of effort.
The male has different plumage to the larger female
"Sadly, there are so few that we may spend a lot of time looking at empty moorland, but we want to be able to say the survey was as thorough as possible," he said.
"By running the hotline, we hope walkers, cyclists and anyone else who spends time in the uplands of northern England will be able to report sightings of the birds.
"Hen harriers are now so rare that if they are out there, we want to go out and see what we can do for them."
Harriers are smaller than a buzzard and larger than a crow, with long wings and long tails, and are usually seen flying low over the ground.
The male has silver-grey upper parts, while the larger female is dark brown. The male harrier performs a magnificent aerobatic display or "sky dance" in spring and passes food to the female mid-flight.
When making reports, the public should include the date and location of the sighting, using a six-figure grid-reference where possible. Details can also be e-mailed to firstname.lastname@example.org.