Walkers will be stepping out for wildlife on Ilkley Moor as part of events around the country to raise awareness of the plight of the hen harrier.
The raptors are perilously close to being wiped out as a breeding bird with only three known nests this year.
Also known as the ghostbird they are illegally killed on intensively managed areas of upland grouse moor.
A protest ramble, organised by a coalition of campaign groups, is being held from 11am on Saturday at the Cow & Calf Rocks on Hangingstone Road on the moors, which is owned by Bradford Council.
The council allows grouse shooting on part of Ilkley Moor for a total of eight days in a season which runs from August 12 to December 10.
But campaigners - who intend to hold a “respectful walk for the moor’s wildlife” - say it should be banned.
Charlie Moores, of Birders Against Wildlife Crime, said: “The fact that our initial Hen Harrier Day has grown so quickly into a dozen events, all organised by passionate volunteers determined to raise the profile of this issue, demonstrates the strength of feeling people have about this wildlife crime.”
Mike Clarke, RSPB’s Chief Executive added: “Time is not on the hen harrier’s side and these Hen Harrier Day events send a strong message that we want our hen harriers back”