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 Climate Change and Animal Populations

In recent years, biologists have noticed changes in ecosystems that reflect changes in climate.

The extinction of the golden toad coincided with reductions in moisture levels in Costa Rica’s cloud forest. Over the past 30 years, the dry season in the area has become warmer and drier, a change that has affected many species. Researchers report that 20 out of 50 species of frogs and toads have disappeared from a 30-square-kilometer study area, and that toucans and other bird species have shifted their range, moving to higher altitudes.

Biologists have reported many biological responses to climate change, including:

- shifts in the ranges of 35 species of non-migratory butterflies.

- a decline in body weight of polar bears, resulting from early melting of sea ice.

- changes in the abundance of winter songbirds in four Great Plains states

- shifts in the species that inhabit California’s tidepools

- reduction of phytoplankton growth in the Ross Sea, a change that could disrupt the Antarctic food chain

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Climate Change and Animal Populations

Climate Change and Animal Populations - The golden toad, last seen in Costa Rica’s cloud forest in 1989, is believed to be extinct. The ecology of the cloud forest depends on the frequent formation of clouds and mist. Warming of the oceans and atmosphere has contributed to declines in mist formation. This has, in turn, affected species native to the area. Source: The Instituto Nacional de Biodiversidad (INBio)

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question Why should I care about the extinction of an obscure species in Costa Rica?

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 research connection  

Science involves observing patterns and looking for trends. In examining biological systems, researchers must be alert to indirect effects, as well as direct effects. Though biologists attribute the disappearance of the golden toad to climate change, they do not say that the shift in temperature and moisture was the direct cause of the population’s decline. Instead, they suggest that climate fluctuations may have weakened the animals, making them vulnerable to the pathogens or parasites that eventually wiped them out.

 related sites  
Biodiversity and Climate Change - A discussion of potential changes in ecosystems, provided by the World Conservation Monitoring Centre.

Warnings from the Wild - An excellent Web site created to accompany a BBC program on climate change.

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