...and threats to food supplies.

The culprit in the massive die-off of Adelie chicks in Antarctica 3 years ago was probably starvation, says Heather Gardner of Australia's Environment, Sport, and Territories Department. Her observations suggest that foraging adult penguins were not bringing enough food back to the colony.

Zoologist Dee Boersma of the University of Washington in Seattle has observed signs of food shortages among penguins in Argentina. At the June meeting of the Society for Conservation Biology in Victoria, British Columbia, Boersma described the surprisingly long-distance travels of Magellanic penguins from the Punta Tombo colony on the Atlantic coast.

In earlier studies, these temperate-zone penguins appeared to fish close to shore. When Boersma and her colleagues recently tracked by satellite two males tagged with radio transmitters, they found the penguins going hundreds of miles out to sea

The powerful swimmers feed on squid, anchovy, and other small fish. During nesting season, adults must frequently shuttle back to the colony to provide chicks with regurgitated fish. Boersma suggests that increases in commercial fishing in the southern Atlantic Ocean have made near-shore food supplies scarce for the penguins, sending them farther out for provisions.

The penguin population at the colony dropped by about 20 percent between 1987 and 1995, although it increased slightly last year. Chicks have the highest mortality rates, and getting sufficient food is the most important factor in their survival, Boersma has found. Oil slicks from tankers pose another threat.

Understanding the penguins' foraging habits is important for conserving them, Boersma and David L. Stokes write in a paper to be published in Marine Ornithology. Although a nearshore reserve around the colony has been proposed, it may not be effective if the birds range far offshore.