California butterflies are reeling from a one-two punch of climate change and land development, says an unprecedented analysis led by UC Davis butterfly expert Arthur Shapiro. In one example, this butterfly, the Clodius Parnassian (Parnassius clodius), is more common at the top of its elevation range in California mountains than in the past. Credit: Heather Dwyer / UC Davis

(University of California – Davis) California butterflies are reeling from a one-two punch of climate change and land development, says an unprecedented analysis led by UC Davis butterfly expert Arthur Shapiro.The new analysis, scheduled to publish online this week in the journal Proceedings of the National Academy of Sciences, gives insights on how a major and much-studied group of organisms is reacting to the Earth’s warming climate. California butterflies are reeling from a one-two punch of climate change and land development, says an unprecedented analysis led by UC Davis butterfly expert Arthur Shapiro. … Their most significant findings:

  • Butterfly diversity (the number of different species present) is falling fast at all the sites near sea level. It is declining more slowly or holding roughly constant in the mountains, except at tree line.
  • At tree line, butterfly diversity is actually going up, as lower-elevation species react to the warming climate by moving upslope to higher, cooler elevations.
  • Diversity among high-elevation butterflies is beginning to fall as temperatures become uncomfortably warm for them and, Shapiro says, “There is nowhere to go except heaven.”

Using a battery of statistical approaches, Shapiro and his colleagues concluded that climate change alone cannot account in full for the deteriorating low-elevation numbers. Land-use data show that the butterfly losses have been greatest where habitat has been converted from rural to urban and suburban types. …

UC Davis study: Butterflies reeling from impacts of climate and development