It is a woodpigeon with adult plumage, so may be sick or injured in some way. It would be best if you can contain him (they are nervy birds, but should not be a problem if he is sick). Maybe a box with plenty of ventilation, cage, other safe enclosure.
If he has not had water he will be dehydrated - needs some slightly warm water with salt & glucose (or sugar). Usual mix is pt of warmish water with 1/2 teaspoon salt and 1/2 Tablespoon glucose powder or sugar mixed in - so even a small pot of water and a pinch of each would be OK..
Give when he has had a chance to settle. Ideally he would be placed on a heating pad first, but most folks don't tend to have them as a matter of course.
They are nervous about being handled, I have to say, but sometimes pigeon beaks have to be guided into water (below nostrils) to encourage drinking.
If you can open the beak and check for any kind of yellow gunge inside, that'll rule in or out one possible problem.
Once he has some liquid in him, he can be fed, but not too soon. Mixed corn, wild bird seed ... thawed out peas and corn ... but first thing is to catch him.
May be a wildlife resource to take him, but I don't know relative locations in Scotland too well. Will check
Will move this to 'Woodpigeons and others.....' section so UK people will pick up easier.
John
