South Devon is the only place in England where you can see cirl buntings
The prolonged cold snap in Devon is endangering the survival of small garden birds, according to the RSPB in the county.
The charity has warned that the savage winter is pushing wildlife in the South West to the "brink of a crisis."
The RSPB says there are ways people can help birds through the freezing conditions.
And it has linked up with farmers to ensure "emergency feeding" of Devon's rare cirl buntings.
The bird's UK population is restricted to South Devon and farmers have been given bird food to put out for them.
Garden birds will also be reliant on food put out for them by householders until the ground defrosts.
"There will be little access to food in the wild for our garden birds," said Tony Whitehead of the RSPB in Devon.
"Normally, the food we put out for them is used by the birds as a top-up. But when the ground is frozen for a prolonged spell, they increasingly rely on the food we give them.
Long-tailed tits need our help during the freeze
"They like high fat content - sunflower seeds are the best. Put it out in hanging feeders, and place the feeders close to cover for the birds - like trees - so they have somewhere to flee to if predators appear.
"They need to feast on that during the day, so they can put on layers of fat to survive overnight. It is that critical.
"But it's not only food they need - water is absolutely vital, so make sure your bird bath hasn't frozen over. If you put water out, you'll see the birds come straight away. They do in my garden."
The birds most at risk are small species such as long-tailed tits, goldcrests and wrens.
"These smaller birds can be decimated in prolonged periods of cold," said Tony. "In previous cold winters, some populations were seriously affected."
There is particular concern for the cirl bunting, which can now only be found in South Devon after being wiped out at all its previous strongholds.
Conservation measures in recent years has seen their numbers in Devon increase from 118 pairs in the 1980s to 700 pairs at the last count.
But special emergency measures are being used to help them.
"Farmers have got bird food to put out for them," said Tony. "They'll be putting food out where there is snow cover on the ground for 24 hours, or frozen conditions for three days.
"Cirl buntings are ground feeding birds so getting food to them is crucial during this cold weather.
"We have all our eggs in one basket with cirl buntings as they can only be found in this area, so if the population is hit, it will have national consequences.
"Hopefully the emergency feeding will help them."
While common garden birds will struggle through the current cold snap, other species are likely to make rare appearances - birds such as the redwing and the fieldfare.