An article by Ernest Williams, the William R. Kenan Professor of Biology Emeritus, was recently published online in Northeastern Naturalist. “The Butterflies (Lepidoptera) of an Isolated Island: Monhegan, Maine” documents the results of Williams’ surveys of the butterflies found on Monhegan Island over the past 21 years.
Williams surveyed the island’s butterfly population periodically from 1998 through 2018 in order to compare the species found on the island to those in the state of Maine in general. He was also interested in how the butterfly community changed over time and whether the island’s habitat and host plants might contribute to some butterflies being found on the mainland but not on the island.
According to Williams, 118 species are found in Maine. He documented 47 species on the island – a “surprisingly high number,” he said, given the island’s small size and location 16 km off the coast of Maine.
He said that not all 47 species were found on the island in a given year but that “about 27 species appear to be residents, and an additional 6 species reach the island regularly each year as migrants or temporary colonists.”
“The butterfly community in this isolated location is changing over time because of human activity, habitat change, and climate warming,” Williams noted. He believes that several species commonly found on the mainland are missing from the island because of the lack of habitat and host plants.
The full article is available on Williams’ website.