Francis is most commonly known for his love and special connection with animals. He considered them his brothers and sisters, as he did all of Creation. (Brother Sun, Sister Moon, etc.). St. Francis' feast day is often celebrated with a traditional Blessing of the Animals. There are many stories of him preaching to birds, taming a wolf, and so on. Many of these stories can be found in The Little Flowers of St. Francis, as well as other biographies. Here are a few from Little Flowers:
preaching to the birds: http://www.ccel.org/ccel/ugolino/flowers.iii.xvi.html
the taming of the wolf: http://www.ccel.org/ccel/ugolino/flowers.iii.xxi.html
taming the wild doves; http://www.ccel.org/ccel/ugolino/flowers.iii.xxii.html
Statue at San Damiano where Francis composed the Canticle of the Sun
St. Francis' Sermon to the Birds
My little sisters, the birds, much bounden are ye unto God, your Creator, and always in every place ought ye to praise Him, for that He hath given you liberty to fly about everywhere, and hath also given you double and triple rainment; moreover He preserved your seed in the ark of Noah, that your race might not perish out of the world; still more are ye beholden to Him for the element of the air which He hath appointed for you; beyond all this, ye sow not, neither do you reap; and God feedeth you, and giveth you the streams and fountains for your drink; the mountains and valleys for your refuge and the high trees whereon to make your nests; and because ye know not how to spin or sow, God clotheth you, you and your children; wherefore your Creator loveth you much, seeing that He hath bestowed on you so many benefits; and therefore, my little sisters, beware of the sin of ingratitude, and study always to give praises unto God.
Saint Francis of Assisi - c 1220
Three years before Francis' death, he decided to re-create the first Nativity scene in a stable in Greccio. He brought together all the stable animals, and the townspeople, and they held Christmas mass in the stable, with Francis chanting the Gospel. This was the first Nativity “Creche” used for Christmas mass and has been used in churches around the world since.
http://www.shrinesf.org/francis06.htm