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Why Are Seabirds Abandoning Their Ancestral Nesting Grounds in Gulf of California?
http://ucrtoday.ucr.edu/30111[font face=Serif][font size=5]Why Are Seabirds Abandoning Their Ancestral Nesting Grounds in Gulf of California?[/font]
[font size=4]Warming oceanographic conditions and fishing pressure are driving nesting seabirds away from their ancestral breeding ground in Mexico into California harbors[/font]
By Iqbal Pittalwala on June 26, 2015
[font size=3]RIVERSIDE, Calif. – 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 Niño”, 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 (Enriqueta Velarde, Exequiel Ezcurra, Michael H. Horn, & Robert T. Patton; Warm oceanographic anomalies and fishing pressure drive seabird nesting north. Science Advances, 26 June 2015) show that ocean warming and overfishing are producing the ecological collapse of the Gulf of California’s productive Midriff region.
Using nest counts in seabird colonies from Mexico and California, they found that Elegant Terns have expanded from the Gulf of California, in Mexico, into Southern California during the last two decades, but that the expansion fluctuates from year to year. “Whenever the terns perceive the conditions in the Gulf as inadequate to ensure successful reproduction,” says Enriqueta Velarde, project leader, “they move to alternative nesting grounds in Southern California including the San Diego Saltworks, Bolsa Chica Ecological Reserve, and Los Angeles Harbor.”
…[/font][/font]
[font size=4]Warming oceanographic conditions and fishing pressure are driving nesting seabirds away from their ancestral breeding ground in Mexico into California harbors[/font]
By Iqbal Pittalwala on June 26, 2015
[font size=3]RIVERSIDE, Calif. – 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 Niño”, 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 (Enriqueta Velarde, Exequiel Ezcurra, Michael H. Horn, & Robert T. Patton; Warm oceanographic anomalies and fishing pressure drive seabird nesting north. Science Advances, 26 June 2015) show that ocean warming and overfishing are producing the ecological collapse of the Gulf of California’s productive Midriff region.
Using nest counts in seabird colonies from Mexico and California, they found that Elegant Terns have expanded from the Gulf of California, in Mexico, into Southern California during the last two decades, but that the expansion fluctuates from year to year. “Whenever the terns perceive the conditions in the Gulf as inadequate to ensure successful reproduction,” says Enriqueta Velarde, project leader, “they move to alternative nesting grounds in Southern California including the San Diego Saltworks, Bolsa Chica Ecological Reserve, and Los Angeles Harbor.”
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