Quite worryingly I just found this on a website: "If you find a baby pigeon the same rules for whether or not you should intervene apply, although baby pigeons are fluffy when they hatch, never actually bald. You should not attempt to feed a baby pigeon - this should only be done by very experienced handlers." One has to wonder why. Do they suddenly, on sight of a human, grow fangs and bite you in a wild Hitchcock-style frenzy? This is quite useful http://britishwildlifehelpline.com/Pigeons.html. A local wildlife rescue centre might be able to help you (or rather, your mum) too.