WINTER MORTALITY OF COMMON LOONS IN FLORIDA COASTAL WATERS

Diagnostic findings are presented for 434 common loons (Gavia immer) f ound sick or dead on Florida beaches from 1970 through 1994, primarily during the months of December to April. The most commonly recognized problem was an emaciation syndrome (66%), followed by oiling (18%), as pergillosis (7%), trauma (5%) and miscellaneous disease entities (1%). The cause-of-death for 3% of the birds was not determined. Many of th e carcasses examined (n 173) were obtained during an epizootic which o ccurred from January to March of 1983 in which more than 13,000 loons were estimated to have died. An emaciation syndrome, characterized by severe atrophy of pectoral muscles, loss of body fat and hemorrhagic e nteritis, was the primary finding in this epizootic. It was postulated to have a complex etiologic basis involving synergistic effects and e nergy costs of migration, molting and replacement of flight feathers, food resource changes, salt-loading, intestinal parasitism, environmen tal contaminants, and inclement weather.