A flock of Pinyon Jays arrive in a flash of blue, and leave again just as suddenly.

This once mysterious bird is now the subject of over 20 years of intensive research involving over one thousand colour-marked jays by Russell Balda, John Marzluff and their colleagues and helpers. This plain blue bird has turned out to be anything but plain in its biology and behaviour.

Uniquely dependent on the seeds of the Pinyon Pine for food, they have developed a number of behavioural and morphological adaptations to best utilise this resource, above all caching enough seeds each autumn to supply their needs throughout the winter and fuel their unusual habit of nesting in late winter.

Fluctuations in pine-seed supply, both by season and between years, poses special problems for these birds and has led to their extremely flexible and complex social system in which learning and memory play an unusually large part. They store pine seeds and retrieve them with uncanny accuracy; they form lifelong pair bonds and nest colonially, occasionally involving younger birds to help established pairs rear the young; and they use their large vocabulary to coordinate activities within one of the largest known avian societies.

This intriguing story will fascinate both the enthusiastic amateur birder and the professional alike. Packed with information, it presents Pinyon Jay biology in a readable form and places them into the wider context of studies on bird ecology and evolution.

Fine illustrations by Tony Angell, with additional pictures by Caroline Bauder, complete this attractive addition to any birder's bookshelf.

John Marzluff is a research scientist with Greenfalk Consultants in Boise, Idaho and adjunct assistant professor of biology at Boise State University. His interest in behavioral ecology was developed by High School mentors in eastern Kansas. He obtained an under- graduate degree in wildlife biology at the University of Montana and completed his graduate work on the behaviour of Pinyon Jays at Northern Arizona University in 1987. He and his wife spent the next three years living in a one-room cabin in the Maine woods investigating the social ecology of Common Raven. He is currently studying ravens in Idaho as well as assessing the impacts of human disturbance on birds of prey. When he is not chasing birds, he and his wife can be found mushing his team of Siberian Husky sled dogs.

Russell Balda is currently Regents' Professor of Biology at Northern Arizona University, Flagstaff, Arizona where he has taught and undertaken research since 1966. He was born and raised in Oshkosh, Wisconsin. His interest in animal behaviour and ecology were formalised while an undergraduate student at the University of Wisconsin, Oshkosh, where he studied with the late Dr Jacob Shapiro. He received his undergraduate degree in Secondary Education to teach history and biology. He received his Master of Science and Doctor of Philosophy Degrees from the University of Illinois under the late Dr S. Charles Kendeigh. His doctoral dissertation dealt with the breeding birds of the Chiricahua mountains in southeastern Arizona. During this study he developed a deep appreciation for the diversity of birdlife in the southwest, where he has made his home ever since. He is currently studying spatial memory and cognition in seed-caching birds. These studies have been in progress for the past fifteen years.