The Family Under the Bridge by Natalie Savage Carlson (1989, Paperback, Reissue)

This is the delightfully warm and enjoyable story of an old Parisian named Armand, who relished his solitary life. Children, he said, were like starlings, and one was better off without them.
But the children who lived under the bridge recognized a true friend when they met one, even if the friend seemed a trifle unwilling at the start. And it did not take Armand very long to realize that he had gotten himself ready-made family; one that he loved with all his heart, and one for whom he would have to find a better home than the bridge.
Armand and the children's adventures around Paris--complete with gypsies and a Santa Claus--make a story which children will treasure.