2018 Butterfly Count at BTA

Text by Ron Rutowski | President of Central Arizona Butterfly Association. Photos by Marceline VandeWater

On Saturday September 8, the Central Arizona Butterfly Association (CAzBA) ran the 12th annual butterfly count using the Arboretum as a focus. This count is part of a database administered by the North American Butterfly Association (NABA) (https://www.naba.org/butter_counts.html). There are about 450 established count sites in North America and Mexico and each is a circle 15 miles in diameter where butterflies are counted at least one day a year. The count data include the number of each species seen and are entered into a website run by NABA. These data are used in scientific research that monitors butterfly populations and factors that influence butterfly abundance and diversity.

American Snout (Libytheana carinenta), a member of the Nymphalidae family

Queen butterfly, a member of the Nymphalidae family. There are seven subspecies.

The count circle that includes the Boyce Thompson Arboretum is centered on the Superior High School. We routinely visit several sites within the circle: the grounds of the Arboretum, the Arizona Trail trailhead, the Apache Tears riparian area, Oak Flat, Upper Devils Canyon, and the town of Superior. Most counts are run on or around July 4th, a time of high butterfly abundance in most parts of North America. However, this is not a good time for counts in the central Arizona desert because this is the end of our summer dry season and there are relatively few butterflies flying then. So, we do this count in early September.

This year we had 11 counters and ended up seeing a total of 1,415 butterflies and 35 species. The number of species was a little below the average of what we have seen over the last 11 years (average 39 species), but the number of individuals was higher than ever before (previous high just under 1,200 individuals). What was especially interesting this year was that over 847 (60%) of the individuals counted belonged to a single species, the American Snout butterfly! This species is notorious for undergoing huge population explosions in the late spring and late summer. This year the count just happened to fall at a time when this species was spectacularly abundant. The results of the now 12 counts we have done are being compared to climatological data to test ideas about what determines the number of species and individuals we see at the Arboretum.

CAzBA appreciates the Arboretum’s assistance in facilitating and promoting these counts over the years and look forward to many more counts to come!

Reakirt's Blue (Echinargus isola), a member of the Lycaenidae family

Xami Hairstreak (Callophrys xami), a member of the Lycaenidae family