Isla Rasa, in the Gulf of California, is renowned for its massive
aggregations of nesting seabirds. Over 95 percent of the world
populations of Elegant Terns and Heerman's Gulls concentrate unfailingly
every year on this tiny island to nest. Ever since the phenomenon was
described by L. W. Walker in 1953 the island has been a magnet for
tourists, naturalists, filmmakers, and seabird researchers.
During
some years in the last two decades, however, the seabirds have arrived
to the island in April, as they usually do, but leave soon after without
nesting. The first event was the 1998 "El NiƱo," when oceanic
productivity collapsed all along the eastern Pacific coast from Chile to
California. But then colony desertion happened again in 2003, and since
then it has recurred with increasing frequency in 2009, 2010, 2014, and
2015. Researchers and conservationists were asking themselves where are
the birds going when they leave their ancestral nesting ground, and
what is causing the abandonment of their historic nesting site.
A group of researchers from Mexico and the U.S. set out to analyze what was happening to the nesting Elegant Terns (Thalasseus elegans), a model species to monitor ocean dynamics. Their results, published in the AAAS journal Science Advances,
show that ocean warming and overfishing are producing the ecological
collapse of the Gulf of California's productive Midriff region.
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