Sick/Injured Collared Dove *GRAPHIC IMAGE*

Hello, 

not an expert here, just like to feed the garden birds. 

Recently, just the past few days, we have noticed a ill/sick looking collared dove. It is always alone, it looks ill and its feathers look strange, it’s I appear sore, and it quite often falls asleep on branches or bird tables/feeding trays. 

It appears to be eating fine, it flies fine, and it seems aware enough, but it does look sick.

We are trying our best to keep it away from the other garden birds in case the others get sick too. We can’t figure out what’s wrong with it and if it is I contagious thing, is it something that the bird can get treated for, is it too late for it, any advice on what we should do?

thanks 

Nik

p.S - have considered calling a vet or rspca for help/advice but I’d reckon they’d need me to have caught it first. Have went out to see how close/feasible it would be to perhaps get it into a shoe box etc, but as I said, it is well aware of surroundings and flys away.