Age and mouth color in Common Ravens

Article Abstract:

Age cohorts in the Common Ravens (Corvus corax) are based primarily on the mouth and tongue color of the birds. However, consistency of this criterion has not been sufficiently tested. The results of a study conducted on ravens raised from fledgings showed that dominant birds in their first winter may acquire black mouth linings usually ascribed to adults, and highly subordinate birds in their third winter can retain the pink or mottled mouth colors ascribed to juveniles. Mouth color may be more strongly linked to status than to age and thus is not a reliable indicator of age.

Physiological aspects, Ravens, Color of birds, Bird coloration

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A new application for transponders in population ecology of the Common Tern

Article Abstract:

A new approach is proposed for the application of transponders monitoring the population ecology of the Common Tern. The approach involves injecting transponders subcutaneously to mark Common Tern adults and chicks of a colony. Microtagged terns can be identified not only during breeding, but for life as well. Furthermore, body mass and identification codes were electronically stored.

Research, Methods, Terns, Animal marking, Animal tagging

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Population declines of King and Common Eiders of the Beaufort Sea

Article Abstract:

King and Common Eiders that winter in the Bering Sea and north Pacific Ocean, migrate to nesting areas in Russia, Alaska and northwestern Canada. Population trends were examined by standardizing the analysis of migration counts, and the King Eider population was found to have remained stable between 1953 and 1976, declining by 56% by 1996. Common Eider populations fell by 53%.

Bird migration, Ducks

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