Warmer Temperatures Cause Butterflies to Emerge Later: Climate Change Impacts

We all know that climate change is impacting species across the globe. Now, scientists have found that warmer temperatures are causing urban butterflies to emerge later than usual. The findings raise questions about how these colorful insects respond to increases in temperature.

"We know that butterflies emerge earlier in North Carolina than they do in New England, because it's warmer," said Tyson Wepprich, one of the researchers, in a news release. "We also know that cities are heat sinks that are warmer than outlying areas. So we wanted to see whether butterflies would emerge earlier in cities than they do in more rural environments."

In order to answer this question, the researchers examined 20 of the most common butterfly species found in Ohio. They then monitored butterfly populations at several sites from April through October. In all, they looked at data that ranged from 1996 to 2011 to establish when each species emerged at each site every year.

"The combined effect of an urban area and a warmer part of the state appeared to delay emergence in seven of the 20 species," said Wepprich in a news release. "Even though butterflies often change their emergence predictably to small increases in temperature, these species responded in unexpected ways to larger increases in temperature."

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

"Scientists often us analogies for global climate change, such as urban warming, to understand how species might respond to a warmer future," said Wepprich in a news release. "This allows us to estimate which species are more vulnerable to climate change."

The findings reveal that warmer temperatures can drastically impact insect behavior. As our climate continues to warm, it's possible that we'll be seeing far more lasting changes in the future.

The findings are published in the journal Ecology.