The devices help monitor the movements of the bird of prey
Hen harrier chicks nesting in north Lancashire have been fitted out with tiny satellite and radio tags as part of a conservation project.
The group Natural England is monitoring 12 nests at Bowland Fells, following fears it may be lost as a breeding bird in England.
Stephen Murphy, responsible for tagging the one-month-old birds, says the area is a sanctuary for the hen harrier.
The devices help monitor the birds' movements, the ornithologist said.
In other parts of England, the Royal Society for the Protection of Birds (RSPB) says hen harriers are at risk.
The birds prey on grouse chicks and so are often shot or poisoned on shooting estates.
In 2006, Natural England tracked a young hen harrier, nicknamed Olivia, and ornithologists are now tagging her chicks.
Mr Murphy said birds previously fitted with the lightweight devices were "doing fine".
One male chick has been fitted with a radio tag which allows close-range contact with volunteers' equipment.
Another has been given a solar-powered satellite device which could trace it anywhere in the world, within 150m of its exact location.
The device can also measure the bird's body temperature, its level of activity and where it is roosting.
"The birds are so mobile, covering 60 miles in a day, for us to glean any knowledge from them we need the radio and satellite devices," said Mr Murphy.
"The birds are so rare and we need to know why," he added.
"In times gone by, the hen harrier was a very common species from the lowlands to the uplands, but another thing which threatens them is habitat loss and change."
Although breeding sites can be protected, Mr Murphy said that the birds could be persecuted outside those areas.
Last month, the Hen Harrier was included on the government's list of species and habitats for conservation in England.
While the bird of prey is extremely rare in England, it is more widespread in Scotland.