Climate change, land development take toll on butterflies

January 12th, 2010 - 4:56 pm ICT by ANI  

Washington, Jan 23 (ANI): A new study led by UC Davis butterfly expert Arthur Shapiro suggests that California butterflies have been hit hard by the change in climate and after effects of land development.

Shapiro, a professor of evolution and ecology, said: “Butterflies are not only charismatic to the public, but also widely used as indicators of the health of the environment worldwide.

“We found many lowland species are being hit hard by the combination of warmer temperatures and habitat loss.”

The conclusions of the study have been drawn from Shapiro’s 35-year database of butterfly observations made twice in a month at 10 sites in north-central California from sea level to tree line.

Shapiro and his colleagues found that butterfly diversity (the number of different species present) is going down rapidly at all the sites near sea level. It is dipping more slowly or holding nearly constant in the mountains, except at tree line.

They discovered that at tree line, butterfly diversity is actually increasing, as lower-elevation species respond to the warming climate by relocating upslope to higher, cooler elevations.

It was also seen that diversity among high-elevation butterflies is beginning to come down as temperatures are unbearably warm for them and as Shapiro pointed out, “There is nowhere to go except heaven.”

Land-use figures show butterfly losses have been the most where habitat has changed from rural to urban and suburban types.

Shapiro said that one of the most surprising findings was that the number of ruderal (”weedy”) butterfly species, which breed on “weedy” plants in disturbed habitats and are highly mobile is actually coming down faster than “non-weedy” species, which specialize in one habitat type.

Shapiro explained: “Butterfly folks generally consider these ruderal species to be ‘junk species,’ sort of the way bird watchers think of pigeons and starlings.

“So it came as a shock to discover that they were being hit even harder than the species that conservationists are used to thinking about.

“Some of the ‘weedy’ species have been touted as great success stories, in which native butterflies had successfully adapted to the changed conditions created by European colonization of California. That was the case for many decades, but habitat loss has apparently caught up with them now.”

The study, “Compounded effects of climate change and habitat alteration shift patterns of butterfly diversity,” will appear in the journal Proceedings of the National Academy of Sciences. (ANI)

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