Climate change bumps up butterfly flight schedules

Using tens of thousands of museum records, researchers have found that climate change could alter the timing of butterfly flights. That could be bad news for some species if their food plants don’t keep up.

Global warming has already been shown to change the timing of everything from lily blooms to frog calls. But finding enough data to understand how different species will respond across large areas is a tall order. The authors of a new study in Global Change Biology note that “[a]n underutilized source of data with immense potential is found in museum collections, where millions of dated and spatially referenced specimens are available for species across the globe and over time periods of decades to centuries.”

The team decided to make use of this data source to analyze the effect of temperature on the emergence of butterflies. The researchers studied about 48,000 records of 204 butterfly species, dating back 139 years, from natural history and expert collections in Canada. Using each specimen’s collection date, they could estimate the butterfly’s flight season schedule. The team also gathered temperature records taken at Canadian weather stations.

When the temperature rose by 1 degree Celsius, the butterflies’ flight season started an average of 2.38 days earlier, the authors report. The effect was particularly strong for species that weren’t very mobile. That might be because these butterflies are picky about local weather conditions and have a hard time moving to more suitable spots.

What does this mean for the butterflies? “If they emerge too early, they could encounter frost and die,” said co-author Heather Kharouba of the University of California, Davis in a press release. “Or they might emerge before the food plants they rely on appear and starve.” Roberta Kwok | 22 November 2013

Source: Kharouba, H.M. et al. 2013. Predicting the sensitivity of butterfly phenology to temperature over the past century. Global Change Biology doi: 10.1111/gcb.12429.

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