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Climate Change Decimating Butterfly Species, Expanding Habitats

August 20, 2012
Image Caption: The Giant Swallowtail, a southern butterfly historically only seen as an occasional stray in New England, has been present in conspicuously high numbers in Massachusetts in recent years, with scores of reports in 2011 and 2012. It may now be breeding in the commonwealth. Image Credit: Harvard University / Frank S. Model

Brett Smith for redOrbit.com – Your Universe Online

Climate change scientists from around the world have turned to everything from satellite imaging to the latest supercomputers in their investigations, but researchers from Harvard University have gathered data from a less traditional source for their latest study–the Massachusetts Butterfly Club.

According to the scientists´ analysis of the amateur nature group´s almost 20,000 expedition accounts, climate change could be impacting the populations of New England butterflies, decimating traditionally northern species and expanding the habitat of typically southern butterflies.

“Over the past 19 years, a warming climate has been reshaping Massachusetts butterfly communities,” said Greg Breed, lead author on the study that appeared in the latest edition of Nature Climate Change.

Warm weather species like as the giant swallowtail and zabulon skipper showed the sharpest increases in abundance, according to the report. Meanwhile, over 75% of species centered north of Boston, deemed northerly species, are experiencing a rapid decline in their Massachusetts populations. The scientists found northern species that overwinter in the area may be much more sensitive to drought or a lack of snow cover.

“For most butterfly species, climate change seems to be a stronger change-agent than habitat loss. Protecting habitat remains a key management strategy, and that may help some butterfly species. However, for many others, habitat protection will not mitigate the impacts of warming,” said Breed.

The Harvard scientists admitted that several other factors besides climate change could be at play in determining butterfly population dynamics. In a web video, ecologist Elizabeth Crone discussed how an invasive plant species is affecting the Baltimore Checkerspot butterfly. She said the Massachusetts population of this butterfly is increasing “mostly because it switched to from its native host plant to an invasive host species–Plantago lanceolata, narrow-leaf plantain–that´s much more common than its native host plant.”

Breed said increased protection of habitat may have a positive influence to certain butterfly populations and these protections should not be lifted in light of data that showed southerly butterfly populations are on the rise. The report pointed to two of these species–the atlantis and aphrodite fritillaries–that have declined by nearly 90 percent since 1992, yet remain unprotected.

According to the web video, Crone, Breed, and the other Harvard researchers are interested in the conservation and relationships of the different types of New England habitats, like open fields and forested areas. Because of the distribution of the human population–the way people manage both the public spaces and their private land has a great impact on the animal population, according to the video.

The group said they plan to continue work with the Massachusetts Butterfly Club, which they view as a valuable resource for tracking the local butterfly populations.

“Careful datasets from amateur naturalists play a valuable role in our understanding of species dynamics,” Crone said. “Scientists constantly ask questions, but sometimes the data just isn’t there to provide the answers, and we can’t go back in time to collect it. This study would not have been possible without the dedication and knowledge of the data collectors on those 19,000 club trips.”


Source: Brett Smith for redOrbit.com - Your Universe Online