Concerns have been raised after the possible disturbance of a peregrine falcon's nest in the Forest of Dean.
Police have released an image of a man they want to speak to, who was seen climbing over a cliff near the nest on 24 May:
Disturbing the nest risks the birds failing to breed this year.
Peregrines are a protected species, and it's a criminal offence to kill or injure one.
It is also an offence to "intentionally or recklessly disturb the birds" close to their nest during the breeding season.
Officers are working with Gloucestershire Wildlife Trust and the Gloucestershire Raptor Monitoring Group to identify the man and establish his intentions.
There are only a small number of nest sites in the county.
Gloucestershire Police are investigating the discovery of two dead peregrine falcons in the Wye Valley. The rare and protected birds were found dead on Offa's Dyke path near Devil's Pulpit.
Officers are appealing to walkers to come forward with information.
The resident pair of Peregrine Falcons that frequently nest on the roof of Bristol Cathedral have been given a belated Christmas present by the Avon Wildlife Trust - a new nesting box.
The Peregrine nesting box has be placed on the roof of the Cathedral, offering a safe and long term nesting site for Bristol's Peregrines.
Two pairs of falcons have nested on the City Centre buildings for the past few years, and experts say the new box could attract another pair to breed.
If the nesting site is successful - eggs could be laid in it as early as the middle of March.
The Trust are looking forward to watching the development:
Firefighters have rescued a bird of prey trapped in netting on the roof of a property in HMS Drake in Plymouth this morning.
They used an aerial ladder to get to the peregrine falcon, which was trapped in anti-pigeon netting. They used an animal rescue bag that is usually for dogs to hold the bird while they cut it free. It had got its wing and leg caught in the wire but they released it and handed it into the care of the RSPCA.