From page 51 of The Birdwatcher’s Companion to North American Birdlife:
A nineteenth-century German zoologist observed that overall body size tends to be greater in representatives of bird and mammal species living permanently in cooler climates than in those living in warmer climates because large bodies retain heat more effectively than smaller ones.
The Birdwatcher’s Companion to North American Birdlife
Christopher W. Leahy
The quintessential A-Z guide, this is a book that anyone interested in birds will want to have close at hand. First published more than twenty years ago, this highly respected reference volume has been fully revised and updated. It captures the fundamental details as well as the immense fascination of North American bird life in a style that is authoritative, yet fresh, witty, and eminently readable.
Both a practical handbook for amateurs and a handy reference for seasoned birders, it provides accounts of the basic elements of birdlife, as well as a wealth of easy-to-access information on such subjects as bird physiology and anatomy, terms and jargon, name definitions and etymology, and ornithological groupings.
Readers will discover everything from the color of a dipper’s eggs (glossy, white, and unmarked) to the number of species of woodpeckers in the world (216). They will also find more than one hundred of the best-known and most colorful colloquial names for birds, alphabetized and briefly defined. Collective nouns relating to birdlife–for example, “an exaltation of larks”–are included in the “Nouns of Assemblage” section. Biographical sketches of persons responsible for describing or naming a significant number of North American species are also included, as well as handsome and accurate illustrations by Gordon Morrison. And for those who want to go beyond reading about their favorite birds and take to the great outdoors, the book offers still more useful information: descriptive entries on a selection of the best-known birdwatching spots of North America.