For the first time since the 1960s, hen harriers have failed to nest successfully in England.
Just two pairs attempted to nest this year in England, but both failed.
The RSPB had been working with one landowner to ensure that the nest at that site was protected but the eggs then did not hatch.
The Government's wildlife advisors say that the population has been forced into this position by illegal killing.
The RSPB is now working with stakeholders as part of a Defra group to produce an emergency recovery plan for the hen harrier in England.