Since 1975, the North American Butterfly Association (NABA) has organized an annual butterfly count in the United States, which has been expanded to include Canada and Mexico. Each count area is a circle 15 miles in diameter and the count is a one-day census of all butterflies observed within that circle. The count promotes interest in butterflies, and provides results useful to scientists who are monitoring butterfly populations and habitats. An official report is available in the spring of the following year.
NABA’s count is an example of citizen science. Everyone is encouraged to participate, either as a member of the group that visits sites selected by the count leader, or as an observer in their own garden.
This year, NABA has organized butterfly counts on Cape Cod, to be held on four weekends during July.
The count in Falmouth will be held Saturday, July 19, (rain date is Monday July 21) at 10 AM at Crane Wildlife Management Area between the baseball field and the former Nickelodeon Theater.
Knowledgeable people to assist with these counts are needed. Beginners who want to experience butterfly counts are also welcome. To sign up, contact Alison Robb at firstname.lastname@example.org or call 508-564-4331.
The sites visited are the same sites visited in past years on comparable dates so that a comparison can be made. There are many reasons for population changes; weather, insecticide use, and habitat decrease or increase all have an impact. Interesting observations from the Cape counts include monarch numbers dwindling, representative of their declining numbers everywhere in eastern North America; Silver-bordered Fritillaries are becoming scarce in Evans Field in Provincetown due to flooding of that field, Appalachian Brown, which were abundant in the cranberry bogs there, have disappeared.
Bog Copper have increased in numbers in the small bogs at Hatches Harbor and Province Lands in the Cape Cod National Seashore; Cloudless Sulphur have visited the Cape from the south in recent years; and other species which have been increasing are those with southerly ranges, including Zabulon Skipper, Variegated Fritillary, Common Buckeye, and Fiery Skipper. Baltimore Checkerspot have increased in the mid- and lower Cape.
In 2012 and 2013 Giant Swallowtails visited the Cape and may be breeding here.