Sadly, collared doves are one of the main sufferers of a disease
called trichomoniasis (canker). It affects the upper digestive
tract causing lesions in the birds’ throats making it difficult to
feed and eventually to breathe.
The infected bird may die of starvation or possibly choking. It
is not caused by anything that you have done.
However, you can help to prevent it from spreading. The best
course of action is to stop feeding for at least a month. Sweep up
and dispose of any left over food and, if possible disinfect all
In summer, natural food is plentiful so the birds will not
suffer. Your feeding area ought to be free of any infection
by the time the birds return, in search of food, at the onset of
In winter, place food in hanging feeders only. Sweep up any that
falls to the ground each day, to prevent the spread of disease.