Have you ever lost your car in the mall parking lot? Our family avoids this problem by standing next to our parked car before we leave it and taking what we jokingly call "an orientation flight," named for the circling flight wasps take to assess local landmarks when they leave their nests (first described by Niko Tinbergen). We don't really fly, but we do turn around and note a prominent, stable landmarks in the area creating a visual map (although my husband inevitably laughs and says, "We're parked next to that blue car.")
After reading the new book, Nature's Compass: The Mystery of Animal Navigation (Science Essentials) by James L. Gould and Carol Grant Gould, it becomes apparent that our way of navigating the parking lot is not that uncommon for humans. Our internal navigation capability is, however, fairly unsophisticated compared to the navigation systems many other animals use to achieve some pretty amazing feats. For example, the celebrity migrant monarch butterfly must fly a couple thousand miles to a mountain in Mexico without an electronic global positioning system. What it does use is an internal compass, clock and calendar to arrive at the right place at the right time.
In fact, a number of insects have sophisticated navigation systems, particularly those with nests that they need to return to with some accuracy, like the honey bees and ants. Researchers have shown that both honey bees and ants use the sun's position against an internal clock to help keep their bearings. In the absence of the sun, the insects can use patterns of polarized light. (Polarized light is the light that vibrates in a definite pattern in one direction, rather than in all directions.) Certain ants have also been shown to have a method of "step-counting," which allows them to assess distances based on stride length (more about that in an upcoming post). Finally, a number of insects, honey bees and monarch butterflies being prominent examples, use magnetic fields for navigating.
The authors review the scientific literature for vertebrates as well, from cahows that must navigate across vast expanses of water to a tiny island near Bermuda, to migrating sea turtles. The navigation abilities of homing pigeons are featured prominently, as well as some of the details of the controversies that arose around the study of vertebrate navigation. My favorite section is an examination of the possibility of magnetic map sense in humans, which clearly and humorously points out the difficulties of experimenting with human subjects.
After seven chapters about how animals navigate, the final chapter is a poignant look at why understanding how animals navigate is so critically important for conservation efforts. Well-intentioned efforts to reintroduce threatened and endangered migratory species have little likelihood of success if they do not take into account how the animals find their way.
James L. Gould and Carol Grant Gould have written other popular science books that explore the potential cognitive abilities of animals, including The Animal Mind and Animal Architects. Nature's Compass expands this interest in a new direction (pun intended). If you are intrigued by animal behavior or need to brush up on your understanding of the field of animal navigation, this book will be a handy reference.
More books by the Goulds:
This book was provided by the publisher for review purposes.