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Increasing frequency of El Ninos could reduce extinction risk of long lived seabirds- new Point Blue study from the Farallon NWR

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March 7 2018

Point Blue scientists, led by Dr. Annie Schmidt, and partners including UC Davis published a new study using Point Blue’s long-term data from the Farallon Islands National Wildlife Refuge on one species of seabird.  They studied Brandt’s cormorants to model how changing the frequency of the El Niño Southern Oscillation (ENSO) might affect seabird populations.

The scientists expected to find that increasing the frequency of ENSO would have a negative effect on the population. But because ENSO is an oscillatory process that alternates between the unfavorable El Niño and more favorable La Niña phases, increasing the frequency of the ENSO process led to increasing the frequency of favorable conditions as well as poor, and overall the population was larger and less prone to extinction.

When the ENSO process was slowed down, the periods of poor conditions and good conditions both lasted longer, but the poor conditions had more of an impact and the population declined.

The study shows that Brandt’s cormorant, and other long-lived, slow reproducing species, are likely to respond much more negatively to slow varying processes rather than rapidly varying ones. This is important to take into account when attempting to predict extinction risk for a population.

Annie E. Schmidt, Louis W. Botsford, D. Patrick Kilduff, Russell W. Bradley, Jaime Jahncke, John M. Eadie. Changing environmental spectra influence age-structured populations: increasing ENSO frequency could diminish variance and extinction risk in long-lived seabirds. Theoretical Ecology. March 2018

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