A team of researchers focused on 20 common butterfly species in Ohio to examine the effect of temperature and urban density on butterfly emergence patterns. Results revealed a wide range of responses to urbanization across species, but one finding stood out.

“The combined effect of an urban area and a warmer part of the state appeared to delay emergence in seven of the 20 species,” Wepprich says. 

The affected species in these areas emerged days or weeks after other butterflies of the same species emerged in either rural areas in the warmer parts of Ohio, or urban areas in colder parts of Ohio. 

“Even though butterflies often change their emergence predictably to small increases in temperature, these species responded in unexpected ways to larger increases in temperature,” Wepprich says. 

“Scientists often use analogies for global climate change, such as urban warming, to understand how species’ might respond to a warmer future,” Wepprich adds. “This allows us to estimate which species are more vulnerable to climate change. 

“We don’t really know precisely where the tipping point is, or why only some species respond this way, but something is happening here. We’re still working to better understand what’s going on with these butterfly species and what consequences there may be for their populations.”

These findings are described in a new paper, “Unexpected phenological responses of butterflies to the interaction of urbanization and geographic temperature,” published online in Ecology. Lead author of the paper is Sarah Diamond, an assistant professor at Case Western and former postdoctoral researcher at NC State. Co-authors include Heather Cayton, Rob Dunn and Nick Haddad of NC State; Clinton Jenkins of the Instituto de Pesquisas Ecológicas; and Leslie Ries at the University of Maryland.

The work was supported by the Department of the Interior’s Southeast Climate Science Center.