The animal welfare charity is concerned the birds have been gaining access to waste products from a local brewery or alcohol producer.
RSPCA officers have collected a number of birds exhibiting the same symptoms in recent weeks.
Birds from places such as Dawlish, Seaton, Colyton, Exmouth, Exeter, Sidmouth, Starcross and Budleigh Salterton have been treated.
Exeter care agency rated 'inadequate' and in special measures
Bosses at Horizon Care insist change
Raw sewage spews into Plymouth suburb estate and woods
Concerns raised for public health and wildlife in Woolwell
Councillor stands under trees to stop chainsaw massacre
Emergency preservation order now in place
Three years jail for charity box thief
And he can't eat in McDonald's for eight years
Spat over whether 'inadequate' children's services are as bad as MP suggests
Exeter's Steve Race believes they are in 'last chance saloon;
Totnes market not opening in Christmas week
Most traders don't want to do it
