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Climate change and El Niño events could seriously reduce the songbird population in North American Forests. Hi, Iím Dave Thurlow for the Weather Notebook.

Dartmouth College and Tulane University researchers discovered that the black-throated warbler did poorly during years when there was an El Niño climate cycle. These cycles reduce the insect and caterpillar food supply at the birdís breeding grounds in New Hampshire and their winter home in Jamaica. Consequently, the warbler produces fewer young.

El Niño is a natural phenomenon, but there is concern that global warming will increase the frequency of El Niño climate cycles. Strong El Niño cycles could increase the risk of songbird survival and reproduction rates reaching extreme lows or possible extinction.

Scientists are alarmed by population declines in many Neotropical migrant species. These species breed in North America during the summer and spend the winter in Latin America and the Caribbean. Most birds in North American forests are Neotropical migrants.

They service humans by eating large quantities of insects. They can even enhance tree growth by consuming leaf-eating caterpillars.

During la NiŇa years, the birds have more to eat and produce more offspring. This just proves how difficult it is to consistently predict the effects of large-scale regional climate change on ecological systems.

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