Butterflies Heading North
Biologist Camille Parmesan compared the past habitat of the Edith’s Checkerspot butterfly against its current range from Mexico to Canada and found that the insect had moved slightly north in response to climate warming. She determined that the level of population extinction is four times as high at the far southern end of the range (Mexico) than at the northern (Canada). This change in a sensitive insect species was predicted from the 20th century warming of Earth’s atmosphere by about 1 degree F.

The butterfly pictured is laying eggs on Collinsia, an annual plant of the Sierra Nevada high meadows. Annual plants are more affected by weather shifts, and this is one of the factors in the butterfly population shifting as climate changes the habitat of both animals and their host plants.