Despite a cool, damp summer, and anecdotal accounts of fewer butterflies being seen early in summer, the annual Rappahannock County butterfly count showed numbers that were a bit low but in line with some previous years. In fact, they were pretty ho-hum, although that’s not a bad thing — no species’ total was down drastically, and many were up.
Before the count, which was held July 23, I was seeing a lot fewer butterflies around my yard and gardens, particularly swallowtails. These butterflies are generally numerous throughout much of the summer, with numbers increasing toward the end of the season.
With all the rain, many of my plants had grown tall but flowered late, with few blossoms, and I wondered if this may have had an effect. This was especially true with my wood phlox, which is normally a huge magnet all summer for eastern tiger swallowtails (ETSs) and spicebush swallowtails, along with other butterflies, moths, bees and other pollinators.
Old Rag Master Naturalists initiated the Rappahannock count, officially known as the “Washington, VA” count, in 2011, and has managed it ever since. It is one of many counts in the United States as part of the “Fourth of July” count, named because they are held in the U.S. around that time. These and international summer counts are under the auspices of the North American Butterfly Association , or NABA.
Our local count encompasses 19 sites within a 15-mile diameter in Rappahannock centering on the Jones Nature Preserve in Tiger Valley. Although, for various reasons, some of the sites have changed over the years, this is unlikely to affect numbers greatly, according to the count coordinators and other butterfly experts with whom I’ve discussed count results in past years.
In casual chats with some ORMN members who participate annually, my observations of low butterfly numbers before the count seemed to jibe with theirs. I was, therefore, surprised when I looked at the total number on the spreadsheets the chapter sent me for this year’s count. Keeping in mind that even six years is a short time to establish trends, I didn’t find the results to be exceptionally low, or high, in terms of overall totals and changes among species.
The overall total for this year was 1,478, down by almost half from 2015 (2,123) and 2012 (2,380), and up a tick from 2014 (1,291) and 2011 (1,254). The total for 2013 (4,798) is likely an outlier — skewed by a remarkable number of ETSs, 2,375, which represented half of the total that year. However, the next year (2014), the ETS population seemed to crash, with only 30 counted, which also affects that total. NABA had taken over the international count from the Xerces Society, which had originated it in 1975. As I noted in my Aug. 23 column last year, the number of ETSs counted in Rappahannock in 2013 was also the highest number for any year, at any count location, since the first of the international counts.
Butterfly populations, like those of many insects, can boom and bust, but in talking with butterfly experts, I could find no specific factor that seemed to account for the amazing swing in ETS numbers in 2013 and 2014. Then again, ETS numbers have been all over the map historically for the Rappahannock count: 172 (2016), 675 (2015), 615 (2012) and 102 (2011), representing larger fluctuations that for other species. While most other swallowtails followed the same pattern as the ETS, even their population fluctuations were not nearly as extreme.
Although the ETS still numbered among the top 10 butterfly species in terms of total number this year, it only made it to third place. It was beaten out by the beautiful but tiny eastern tailed-blue (226) and the introduced cabbage white (191). All three of these species have consistently ranked in the top 10 by total, along with the silver-spotted skipper. The rest of the top 10 this year, in descending order, are silver-spotted skipper, clouded sulphur, orange sulphur, pearl crescent, sulphur species (only identified down to the genus), silvery checkerspot and great spangled fritillary. All in the top 10 this year had made the list before in at least one other year. No species showed remarkably low or high numbers this year, compared with their numbers in previous years.
Although no single sulphur species numbered among the top three, these species warrant a mention for taking up three slots among the top 10. The only two new butterflies noted on the list were also sulphurs: a new species, the albino sulphur (Colias eurytheme), and a white form of the clouded sulphur. (Some butterfly species have different forms, aka morphs — same species, different coloring — such as the dark form of the female ETS.)
Over the years, ORMN’s butterfly committee had decided to drop several species from the list, which was compiled from a list used in the Fauquier County count, because those species’ numbers were so low and also to keep the count checklist short enough to fit on one page, for easier recording in the field. The species that were cut are mourning cloak, giant swallowtail, long dash, painted lady and whirlabout.
(For more on results of the counts on other years, search on “butterfly count” at rappnews.com.)
© 2016 Pam Owen
ORMN looks for new members
Old Rag Master Naturalists has just announced that they are looking for new members for their training class next March. Becoming a certified Virginia Master Naturalist requires 40 hours of training, with eight hours of continuing education in subsequent years. Only 13 slots are available for ORMN’s 2017 class, and typically competition is vigorous, so anyone interested should apply as soon as possible. For more information, go to the chapter’s website or contact Roberta Jalbert at 540-407-0552 or firstname.lastname@example.org.