MAGELLANIC PENGUINS (SPHENISCUS-MAGELLANICUS) AFFECTED BY CHRONIC PETROLEUM POLLUTION ALONG COAST OF CHUBUT, ARGENTINA

In March of 1982-1984 and 1986-1990 we counted carcasses of Magellanic Penguins (Spheniscus magellanicus) along the Chubut coast of Argentina. The number of carcasses found per kilometer of beach on the shoreline ranged from 49 in 1982 to 9 in 1990. In 1984, 22% of the dead penguins were oiled as compared to 66% in 1987. Oiled penguins were found along all parts of the Chubut coast showing that chronic oil pollution is not a local problem. Oiled carcasses were more common near oil ports, where oil pollution is probably worse, and they were more common on headlands than away from the ports or in bays. More fledglings than adults were found dead along the coast. Approximately 65% of dead adults and 31% of dead fledglings were oiled. In years when the natural mortality rate was low for adults (1986 and 1987), a higher percent of the carcasses had petroleum, suggesting oil was an important cause of adult mortality. Starvation appeared to be the most common cause of death for fledglings, whereas petroleum pollution was the main cause of death for adults. We estimate that at least 1.1% of the adult population and 6.0% of the fledglings are oiled in February and March of each year. Since penguins migrate twice a year, more than 20,000 adults and 22,000 juveniles may be killed along 3,000 km of Argentine coast (Chubut and Santa Cruz) each year due to oil pollution. These data suggest that chronic petroleum pollution is a significant mortality factor for adult Magellanic Penguins along the coast of Argentina and may be depressing population numbers.