The butterfly count, held on August 6th this year, started out as touch-and-go. In the days leading up to the count, the weather forecast got grimmer and grimmer with it ultimately being “cloudy and a 70% chance of thunderstorms.” Now, if we were doing amphibian monitoring, that would have been a terrific forecast but butterflies prefer temperatures in the high 70s at least and they don’t fly in the rain.
As morning broke though, the cloud cover was high so we were hopeful. Eight teams, with 59 people, gathered at their meeting spots a little before 9am. It was still cool at that time, around 75 degrees, and with the exception of the Blue Ridge Center, the morning had a slow start.
By about 10am, the butterflies were showing up. The cloud cover and slight breeze made for a more comfortable day than we’ve seen in past years and temperatures reached the mid-80s – perfect for butterflies! But where were they?
Across the board numbers were down. In terms of diversity, we had 43 species (compared to 47-49 in past years) but it was the number of individual butterflies that was profound, as we recorded just 2312 individuals. This is the lowest count we’ve seen since 2004 and a huge departure from the last two years where we saw well over 4,000 individuals each count.
While numbers were low across the board, we especially noticed that the swallowtails, fritillaries and sulphurs were almost absent in locations where they are typically seen and in general their numbers seemed to be cut in half. Monarchs were low at just 52, compared to 193 in 2009 and 82 in 2010.
The Red-banded hairstreak was higher than in past years and the American Copper showed up at a couple of different locations, giving many participants a “lifer”. The Common Buckeye, Eastern-tailed Blue, Silver Spotted Skipper, Dun Skipper and Zabulon Skipper all had healthy numbers on par with past years.
All in all, a nice day for the count but the lack of butterflies has had a lot of us asking what happened? We didn’t have the best day for the count with the cloud cover but it was warm enough that the butterflies would have been out if they were around and the showy swallowtails could not have been missed.
It all comes down to weather and habitat for butterflies. The cool spring with its rain storms may have been too much for the adults to handle. That, followed by the heat we had through July, may have made it so the caterpillars/chrysalids couldn’t survive or develop.
In the weeks leading up to the count, I scoured the listservs and across the country fellow butterfly counters were reporting low numbers and asked the same questions we did. I just wondered if our count would bear out the same truths, and it did.
What are the butterflies telling us on a national level? In the fall, the North American Butterfly Association, where we submit our data, will have the national data compiled. It will be interesting to see the conclusions they draw.
You can view our Loudoun County data from 1997-2011 on our website: https://loudounwildlife.org/Butterfly_Count_Summary_Data.htm
Our thanks go out to everyone who participated in the count this year! We couldn’t have done it without you!
If you missed the count this year, mark your calendars now for next year! We hold it on the first Saturday every August.