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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
- 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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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.
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glossary terms
