Made For Each Other: A Symbiosis of Birds and Pines
(Oxford University Press, 1996)
There are roughly 110 species of pines in the world, about a third of which are in the "white" or "soft" pine group. While we usually think of pines as having winged seeds capable of being carried long distances on the wind, about two-thirds of the soft pines have big, heavy "nuts" that are entirely or nearly wingless, and that cannot be dispersed by wind. Worse yet, many of them have cones that do not open to release the seeds. How, then, do these pines spread across a landscape?
Fortunately, the fat- and protein-rich seeds of these pines are very attractive to creatures of all sorts. People have always enjoyed eating them -- as pinones, Indian nuts, pine nuts, pignolias, etc.-- and they are found in many cuisines. Squirrels do acrobatics to procure them. Bears love them, and grizzly and brown bears fatten on them before hibernation. But most importantly, "Corvids" are crazy for them. Corvids are birds of the crow family, in this context jays and nutcrackers. Whenever there is a seed crop of these pines, corvids pluck the seeds from the cones and bury, or cache them in the soil as a winter food source. When the corvids feed from the species with closed-up cones, they first cleverly remove the cone scales to reveal the seeds.Throughout the long mountain winters, the birds dig them up and subsist on them, even tunnelling through snow to find them.
But in years when a bumper crop of seeds is produced, and millions are buried, not all will be retrieved. So the next spring, many little pine seedlings will sprout from caches made by birds. Many, perhaps all, of the pines that have flightless seeds depend on the corvids to carry them long distances and bury them in the ground where they can germinate and become established. And some of the corvids depend on these seeds as a year-round food source, and the nutriment for their nestlings, thus forming a symbiosis or mutualism. A surprisingly large area of the earth is covered by corvid-dispersed pines, in North America, Europe, and Asia; yet their story is little known even to the natural-history-obsessed public.
This book, based largely on the author's twenty years of research involving several pines and nutcrackers, brings together in an accessible style the world literature on these fascinating symbioses.It covers the natural history of pines and corvids, bears and squirrels. It describes how field research is done, and how scientific data are collected and interpreted from the standpoint of a scientist who has done these things. It goes from ecology to genetics, evolution to ornithology, psychology to systematics.
Made For Each Other is 6 X 9 in., has 160 pages, 15 color photos, numerous b/w photos and sketches, and a great cover photo I took of a Clark's Nutcracker perched atop a limber pine tree in northern Utah, among opening cones and with a seed held in its bill.
It has fourteen chapters, fascinating backnotes, twelve pages of references, and a six-page index.
Oxford University Press is now filling new orders "on demand" digitally at $19.95 for paperbacks only. Unfortunately, the photos are all black/white, though the text is unchanged.