Wild Ideas: Butterfly numbers generally hold steady in this year’s count  

With the fall butterfly migration likely over here for the year, I turned to the results of the 2017 butterfly count here in Rappahannock County to see how our local species had fared. The bottom line is that the numbers show no cause for concern or elation compared with previous years.

The count, officially, the “Washington, VA” count, was founded and is managed by Old Rag Master Naturalists (ORMN), was held on July 22. It’s part of the annual “July 4” count of the North American Butterfly Association (NABA).

Butterfly monitoring data gathered in the field is prone to be affected by several variables, the most important being the weather. Fortunately, the weather was good — warm and dry — for this year’s count. And, as always, ORMN had a good volunteer turnout for its count, including experts and many repeat volunteers.

Although the sites counted have varied slightly over the years here, all are within a five-mile diameter circle required by NABA. For the past three years, the same 19 sites were counted. Several have been naturalized to attract pollinators, so generally attract more butterflies. The count gives a good snapshot of butterfly populations within the county on the day. And as data accumulates over the years, trends do emerge, although six years of data is still too small a pool for discerning trending.

Among the most common species, the data show some fluctuate from year to year but no big surprises. The total butterflies counted, 2,377, was close to previous years. The species with the highest numbers were also no surprise — all made the top-10 list in at least one other year: silver-spotted skipper (318), eastern tiger swallowtail (302), silvery checkerspot (296), cabbage white (275), eastern tailed-blue (172), spicebush swallowtail (119), pearl crescent (99), variegated fritillary (78), clouded sulphur (67) and orange sulphur. “Skipper spp” actually came in ninth, but that category combines skippers that could not be identified down to the level of species (of which there are many). Identifying skippers is a hard task for even experts, considering most species are tiny, brown, quick and always on the move.

By Pam Owen
The silver-spotted skipper, shown here nectaring on native phlox, this year scored the highest numbers in Rappahannock’s annual butterfly count.

Some species can have enormous swings in populations from year to year, so looking for upward or downward trends in those species can be even trickier than for species with steady averages. The star of boom and bust here is the eastern tiger swallowtail, which has had the following totals since 2011: 102, 615, 2,375 (a record for the national count), 30, 675, 172 and, this year, 302. And these numbers don’t include swallowtails lumped into “Swallowtail spp.” Female eastern tigers can take on a dark form that is similar to other dark swallowtail species, so often get lumped into this collective category.

The top 10 species when totals are combined for all six years (excluding swallowtails not identified down to the species level) are eastern tiger swallowtail (4,271), eastern tailed-blue (1,442), silver-spotted skipper (1,441), cabbage white (1,356), silvery checkerspot (857), spicebush swallowtail (606), pearl crescent (529), great spangled fritillary (507), clouded sulphur (487) and orange sulphur (394).

Among the no-shows this year was the red admiral. This species tends to be more active early and late in the warm season, so never has high numbers at the time of the count in any year, but this is the first year none were spotted. Other no-shows were mostly species whose numbers have hovered close to zero in previous years, so not worth noting. The only new species to be counted this year was a lone northern cloudywing, although at least one southern cloudywing has shown up most years.

By Pam Owen
Eastern tiger swallowtails have the highest total over the six years of Rappahannock’s butterfly count, partly because of a national record-breaking number in 2013.

Anecdotally, numbers for some butterflies migrating through before or after the count seemed higher. The most common butterflies I saw during my vacation on the Outer Banks of North Carolina around the autumnal equinox were painted ladies, which were migrating. When I returned to Rappahannock County, the first butterflies I saw were also several painted ladies — on nonnative flowers that were still blooming in front of our farmers’ co-op. The last butterfly I’m likely to see this year was the same species, cruising blooms of potted plants at Headmasters in Sperryville on Nov. 3., apparently a migration straggler. Although two painted ladies were recorded in the Rappahannock butterfly count this year, there was only one recorded before, in 2014.

Luke Christopher | Rappahannock News
While few painted lady butterflies showed up in the Rappahannock butterfly count, migrating ones seemed plentiful here (left) and on the Outer Banks of North Carolina.

As for monarchs, the poster child of butterflies, anecdotally I was seeing and hearing about increased numbers during their spring and fall migrations. Monarchs typically are more numerous in open areas, such as the plains states of the Midwest, than in the more heavily forested East, so they always put in a poor showing during the count. Averaging four over the previous years of our count, this year, at 17 recorded, they more than quadrupled their average and more than doubled their previous highest number (eight, in 2012). Again, at these low numbers, this uptick doesn’t mean much but is still nice to see.

A Journey North, a monitoring project for citizen scientists to help track migrating species, including monarchs, has been reporting good numbers for sightings of monarchs migrating or that have arrived in their main overwintering sites in Mexico look promising. It will be interesting to see the totals from the NABA counts across North America this year, which NABA typically publishes early the following year. To find out more about the monarch, including animated maps of their migration, and how to help them, go to Journey North’s website.

Frankly, while I welcome the sight of butterflies of any species, including monarchs, I’d be more concerned if Virginia’s forest species, such as the swallowtails, were trending downward. Fortunately, that does not seem to be the case — so far.

© 2017 Pam Owen

Pam Owen
About Pam Owen 286 Articles

Writer, editor, photographer, and passionate nature conservationist living in Rappahannock County, in the Blue Ridge Mountains of Virginia. Two favorite quotes: By E.O. Wilson, who coined the term “biodiversity,” “Nature holds the key to our aesthetic, intellectual, cognitive and even spiritual satisfaction”; by Douglas Adams, “I love deadlines. I love the whooshing sound they make as they pass by.”

Be the first to comment

Leave a Reply

Your email address will not be published.


*