Each year, in the 4 weeks before or after the 4th of July, the North American Butterfly Association, NABA, sponsors a butterfly count across the nation. Here in San Francisco, Liam O’Brien manages it, maneuvering around the fog of summer. Two years ago, we nearly didn’t get one owing to the weather, but he pulled it off at the last minute in late July. This year, it was in good time, on the 15th of June.
This year, spotters found 24 species of butterfly, with 777 individual butterflies. They identified 734 by species (a few could only be identified by family). This is slightly better than last year, though down from the boom years of 2011 and 2012. No rarities were spotted this year, but the Woodland Skipper made a reappearance from 2012.
The Cabbage White butterfly is back on top for 2014. It’s topped four out of five counts, though the numbers are slightly down from the first three years. But in 2013, the number of Pipevine Swallowtails exceeded the Cabbage Whites.
The Cabbage Butterfly numbers aren’t really higher this year; it’s just that no other species was seen in large numbers.
The second was the Common Checkered Skipper, a small butterfly that’s widely found across California and most of North America. They saw 106 of them, more than twice the largest number in the past four years. Curiously, according to the butterfly website of UC Davis Professor Art Shapiro, California seems to have at least two species of these – and a third that’s genetically very similar to one of them but can’t interbreed with it.
Third was the Common Buckeye. This butterfly is dramatic enough that the US Postal Service put it on a stamp! (That’s the picture at the beginning of this article.) Male buckeye butterflies often perch on the ground, and both males and females visit a great variety of flowers.
The top three butterflies accounted this year for 41% of the insects spotted; other years, it’s ranged from 44-50%.
Which were the top three in earlier years? The distribution has been less stable than one might expect. Many factors can affect butterfly sightings – weather on the day of the Count; the weather the previous winter and spring that could affect the plants the butterflies (and their caterpillars) need for breeding and feeding; and just random changes.
- The top three butterflies of 2013 were the Pipevine Swallowtail, the Cabbage White, and the Echo Blue, AKA the Spring Azure.
- In 2012, it was Cabbage White in first place, with the California Common Ringlet and the Sandhill Skipper tying for second place, and the Common Buckeye in third place.
- In 2011, the Cabbage White, Anise Swallowtail, and Echo Blue.
- In 2010, the Cabbage White, the Umber Skipper, and the Anise Swallowtail.
THE TOP TEN
The graph below shows the top ten species for 2014, and compares the numbers to earlier years. The top ten this year accounted for 78% of the total number of insects spotted; in earlier years, it was 82-85%.