Wednesday, May 21, 2014

Macaroni penguin populations under threat from other seabirds


The greatest threat to declining macaroni penguin numbers in the South Atlantic island of South Georgia, have been found to be the seabird giant petrels who prey on the chicks and fledglings
Led by researchers from the British Antarctic Survey, the team of scientists been fitting tiny electronic tags to adult and fledgling macaroni penguin since 2003. Then, using an electronic scanner placed at the entrance to their colony, they have been recording each bird’s identification number as it came and went, over a period of ten consecutive breeding seasons.
Lead author Catharine Horswill, from BAS, says:
“Penguins are facing rapid changes in their environment, but at South Georgia, in the southwest Atlantic, we found compelling evidence that predators are the most important factor influencing the survival of chicks as they leave the colony for the first time. This is a big leap forward as we had no idea that predation could be such a strong driving force. Knowing what drives survival rates of penguins puts us in a much better place to predict how these populations may change in the future.”
The macaroni penguin population on the South Atlantic island of South Georgia has declined by almost seventy per cent since the early 1980s. Previous studies on penguin survival rates have focussed on the influence of environmental pressures. This study shows that macaroni penguins are influenced by both environmental and predation pressures. The scientists found penguins were particularly vulnerable to predation by other seabirds, giant petrels, which also nest on the island. Chicks were found to be particularly vulnerable with only a third surviving their first, fledgling, year.


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