Ernest H. Williams

“A long-term survey of spring monarch butterflies in north-central Florida,” co-authored by Ernest Williams, the William R. Kenan Professor of Biology Emeritus and Lecturer in Biology, appears in the current issue of the Journal of Natural History.

The study showed that the migration of monarchs from Mexico is timed to reach areas in the southern U.S. when milkweeds are in prime condition for monarch egg laying and larval feeding. Newly emerged monarchs in northern Florida then continue the migration into the northern U.S. and southern Canada.

Standardized surveys at the study site showed an 80% decline in monarch abundance over the past 24 years, a loss that parallels the decline in the number of monarchs overwintering in Mexico.

According to Williams, the research presented was started in the early 1980s by the late Lincoln Brower, formerly of Sweet Briar College. He said many people have contributed to it over the years, resulting in 13 co-authors.

Williams ran the data analyses for the study, and he and Brower, who died in July, wrote the paper which was Brower’s final published study.

“He studied monarchs for 50 years and did more than anyone else for their conservation,” Williams said of Brower. The two collaborated extensively over the past 12 years

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