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Southern Species of US Butterflies are Moving North as Climate Shifts
Between droughts, super storms and wildfires, it’s easy to overlook some of the smaller, more subtle effects of climate change. As the planet warms, populations of plants and animals shift, adjusting their territories to deal with new conditions. A paper published last year in Nature Climate Change reported on the movement of southern butterfly species in the US. Many are packing up and moving north, establishing themselves in new sites. Subtropical and warm climate butterflies have shown the greatest movement. While southern pollinators are traveling towards states like Massachusetts, more than 75 percent of northern species have shown a decline in population, with those that overwinter eggs and larvae showing the fastest reduction in numbers. This is most likely due to the presence of drought and lack of snow cover resulting from global warming.
As lead author of the study Greg Breed explains, climate seems to be a greater change-agent than habitat loss. While it is still critical to protect the places where these butterflies live, it may not mitigate the overall effects of warming. For example, in Massachusetts the frosted elfin, a species that once needed protection from the state, has increased its numbers 1,000 percent since 1992. At the same time, common summer butterflies like the atlantis and aphrodite fritillary have decreased by 90 percent.
“Conservation agencies should not use our results to infer that all southern species are safe nor that all northern species are doomed to extinction. However, understanding mechanisms of population decline could improve management practices and limit potentially costly efforts that will have little influence on species conservation.” noted the paper.
Much of the information was gathered by citizen scientists at the Massachusetts Butterfly Club over the last 19 years. Over the course of 20,000 expeditions throughout the state, backyard biologists have been adding to national research documenting butterfly movement, “escalator effects,” breeding, and urban roadblocks. As the heat rises, butterflies are becoming harbingers of major changes to come.
Via Mother Jones
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