Tortuga by Paul Geraghty
Heavy with eggs, a small tortoise finds herself washed up on a remote island after a storm. Disaster strikes when a flock of seagulls steal the precious eggs and so she sets off in search of another mate. The whole island is explored and it seems that she is the only creature of her kind left in the world. Then one day, she sees a whole scramble of baby tortoises coming towards her! Not all her eggs have been lost!