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by Carl Hertzmann
NEW GUIDES -There have been several new bird guides published, of which two are important enough to bring to your attention. The Sibley Guide to Birds, published by the National Audubon Society, is an awesome achievement by a single author. There are about 6,500 paintings of the birds of North America, showing subspecies, various plumages, birds in flight, et cetera. This is the most comprehensive and accurate guide to bird identification that has been published. It is somewhat bulky to use in the field, though many are using it as a field guide; as a reference, it has no peers. Published in 2000, it has sold over 500,000 copies, indicating its popularity and the popularity of birding. In general, I do not like bird photographs in a field guide; because of variations in lighting and films, photographs can be misleading. An exception is Birds of North America by Kaufman. The photographs are digitally enhanced to highlight identification marks. (A similar system is used in the Peterson guides.) This enhancement is successful. Kaufman's Guide has the best written descriptions for identification available. A drawback is that, given the relatively small size for a book covering all of North America, the author is limited in showing various plumages and birds in flight. Furthermore, the colors in some of the birds appear to be washed out. Nevertheless it is a good guide. As a first guide to the birds of Eastern North America, I prefer the Peterson Field Guide. Note: I have mentioned previously the excellent guide, Butterflies Through Binoculars by Glassburg. There is now a western edition of this book. If you are interested in dragonflies, get the similar Dragonflies Through Binoculars by Dunkle.
SLEEP PATTERNS IN BIRDS - In my discussion on sleep patterns in birds [see the TMLA Newsletter, Spring, 2001] I failed to mention bills and legs. These structures lack feathers and can be a source of heat loss in cool weather, though the legs have a shunting vascular system to decrease this risk. Some birds, such as swans and geese, will sleep with their bills tucked in the feathers of the back to prevent heat loss. One leg, for similar reasons, may be tucked up into the belly feathers, making the bird appear one-legged. I have even seen sandpipers hopping about on one leg while feeding.
EFFECTS OF CHANGING BIRD POPULATIONS - As has been mentioned in this Newsletter, Canada geese love to feed on lawn grass; they nibble it and do not pull it up by the roots, and thereby do not destroy the habitat. Contrarily, snow geese are destroying the habitat. The population of snow geese has exploded due to the improved food supply in the winter habitat of the deep South. Where they used to feed on a limited food supply in the deltas and bays, their food supply is now abundant and the population is exploding. When they migrate, they are denuding the fragile tundra in the Arctic region and turning it into a semi-desert, to the detriment of other birds and animals dependent on the tundra. This is an example of the inadvertent effect of humans on animal life. Other examples: (1) the competition of starlings for the nesting cavities used by flickers is causing decreased flicker populations. (2) House finches, a western bird, were released by a pet store in New York City; they have spread west and are having a negative impact on the English sparrow, another introduced species. (3) Mute swans have escaped into the wild and are now breeding along the East Coast and the Great Lakes. They are very aggressive and territorial and are having a negative impact on other birds, including nesting trumpeter swans. Trumpeter swans reintroduced to a wildlife area on the south shore of Lake Erie are being pushed out by the mute swans. Could this sort of thing happen in Minnesota?
FROM MY WINDOW - There have been pairs of phoebes nesting under the eves of our cabin at the same spot for years. Birds are often faithful to the same nesting site. In 2001 the last brood was fledged the end of July. I have seen mallards and mergansers with broods of small ducklings in late July. Birds need time to become strong enough for the rigors of migration and winter. I wonder if these late broods will make it. Hawks and owls will nest early, even in late winter, so the young will be strong and experienced enough to survive the following winter, or migration.
