When a starling fell into her life. . .; Arnie, the Darling Starling, by Margarete Sigl Corbo and Diane Marie Barras.Illustrated by Leslie Morrill. Boston: Houghton Mifflin Company. 231 pp. $9.95.

''Kiss Arnie! I love you. He's a coo-coo!'' says Arnie, a vocal bird who is actually a starling. In their new book Margarete Corbo and Diane Barras have given this much-maligned species a chance to speak in its own defense.

Corbo found a nestling in her southeast Texas garden at a time when she was floundering around, trying to find a new sense of direction in her life. In that way she was like the starling, she thought.

She was ignorant enough about wild birds not to know the species she had on her hands, or that its parents would most likely look after it even out of the nest. She wanted to care for the bird. She needed it.

Her effort to reach out to an animal was the first step out of her own difficulties, in a sense an awakening.

Corbo's story, written with the help of her friend Diane Barras, is an account of how bird and woman helped each other. Corbo made mistakes, both in her own affairs and in caring for the bird, but learned to correct them. She and Arnie survived and, having sorted themselves out, eventually settled down on Cape Cod.

No doubt their innate vitality and ability to love helped them do it.

We are often warned against attributing human characteristics to animals, which have their own reasons for doing what they do. But most of us have stories to tell of the intelligence and warmth of affection animals seem to exhibit.

Margarete Corbo has no doubts about the ability of animals to express themselves in ways human beings can understand.

The book is written in a popular style and is very well constructed, but it could have done with a less cutesy title. Nonetheless, it may be destined to join the classics of animal-human relationship stories such as ''Rascal'' and ''That Quail, Robert.''