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Habitat use at night by wintering American woodcock in coastal Georgia and Virginia

Nocturnal habitats used by American woodcock (Scolopux minor) were studied using radio telemetry at two coastal wintering sites in Georgia (1982-84) and Virginia (1991-92). In Georgia, use of forested habitats at night was extensive while use of fields at night varied between years but generally was low. We found no difference in the probability of moving to a field at night among the four age-sex classes (P = 0.23). A significant effect (P < 0.05) of age-sex class was noted between distances moved from diurnal to nocturnal locations in Georgia. Young females moved farther than any other age-sex class. In Virginia, no effect of age-sex class was found on the probability of being located during the night in either a field or a forest.

Audubon Field Notes↗

Evaluating causes of population change in North American insectivorous songbirds

Although the North American Breeding Bird Survey (BBS) is a principal source of information regarding populations of most North American bird species, many features of the survey complicate analysis of population change. Correlation studies based on BBS data cannot be used to unambiguously define cause and effect relationships. Recently, B?hning-Gaese et al. (1993) presented an analysis of population trends in insectivorous songbirds using data from the BBS. They concluded that predation has played an important role in influencing population trends. We review aspects of the analysis methods for estimating population trends (e.g., observer effects, data subset) and for associating mean trends with species attributes (e.g., confounding of attributes). Using alternative analyses of the same BBS data, we demonstrate that the evidence that predation is associated with population declines is weaker than they suggested. Based on our analyses the only factor among those tested that is consistently associated with population trends is migration status (i.e., short-distance migrant/resident vs. long-distance migrant) during the period 1978-1987. Also, we present evidence that the harsh winters of the mid-1970's severely depressed populations of short-distance migrant species, and may be responsible for the observed associations between migration status and population trends.

Audubon Field Notes↗

Field Marks of a Celebration: Roger Tory Peterson's Centennial Birthday

A red letter day in my life was April 27, 1934, the day I first met Roger. A birding friend, Elisha Atkins, had invited Clinton Reynolds and me to dinner to meet a famous ornithologist. We would all be going on a field trip to Newburyport on the Massachusetts coast the next day. The dinner conversation revolved about a new field guide that Mr. Peterson had just completed and that would be available in a few days. I couldn?t wait to see it! I had been birding since 1930, keying out live birds with Chapman?s Handbook of Birds of Eastern North America (1912) and Hoffman?s Guide to the Birds of New England and Eastern New York (1904). Both books had extensive keys based on color, size, bill shape and season, and pictures of heads or feet of some species. Positive bird identification was a long and tedious process. The field trip the next day with Roger was memorable, not for finding any rare or unusual birds, but for learning how to identify birds to species at a single good glance. I recall asking Roger if he could find a ring-billed gull among a group of gulls resting on a roof beside the Merrimac River. He immediately said, ?No there aren?t any ring-bills there; they would be immediately apparent by their slimmer shape.? There was no need to check the foot color on each bird. While it is easy to say that Roger revolutionized field guides, I truly believe there are few people worldwide under the age of 90 who can really appreciate the difference between the old way of keying out birds and the instant recognition promoted by the Peterson system. Today we take for granted that amateurs can identify birds accurately. Monitoring bird populations by Breeding Bird Surveys, atlas studies, Breeding Bird Censuses, migration banding, and many other studies relies on it. None of these would be possible if we were still keying out live birds using books designed to identify dead birds in the hand.

Audubon Naturalist News↗

The Emperor Goose

Many ornithologists believe the emperor goose ( Chen canagicus ) is the most beautiful goose in North America. Detailed descriptions of its plumage can be found in Palmer 1 and a general description in Bellrose. 2 Emperor geese are rather short and squatty, with yellow-orange feet and pink bills. Their bluish-gray body feathers are banded in black and fringed on the outside edge with white. The beads and necks of adult emperors are white except for a wide, dark-gray band that begins at the throat and extends down the neck to the breast. The plumage of immatures more than four months old is similar to that of adults. Before four months their heads are gray.

Audubon Wildlife Report↗

Polar Bear

No abstract available.

Audubon Wildlife Report↗