Annual Yosemite National Park Butterfly Count

Jeffrey Glassberg, Karen Amstutz, and Ryan Carlton searching for butterflies.

Jeffrey Glassberg, Karen Amstutz, and Ryan Carlton searching for butterflies.

Yosemite National Park initiated its fourth annual butterfly count in the Tuolumne Meadows area in summer 2014. Yosemite coordinates this event in association with the North American Butterfly Association (NABA), an organization that conducts long-term monitoring of butterfly populations all over North America. The purpose of the NABA counts is to determine how many species and individual butterflies can be observed within a 15-mile diameter circle, during a 24 hour period, within the same date-span year after year. Participants spend the day gathering data toward long-term monitoring; raising public awareness toward butterfly conservation; and socializing and having fun with other butterfly devotees.

Ruddy copper <i> (Lycaena rubidus) </i> butterfly

On the morning of July 28, 2014, under a smoky and ephemerally sunny sky, a record-setting number of butterfly experts and enthusiasts met at the Lembert Dome parking lot in Tuolumne Meadows. As the leaders introduced themselves, feelings of admiration and respect flowed freely within the group. These expert lepidopterists came from around the state and beyond, to convene in Yosemite’s beautiful high country to spend the day sharing their knowledge and intense appreciation for butterflies and natural history.

Following introductions, instructions, and the dissemination of count datasheets, the larger group divided up into six smaller groups, each led by one or two butterfly experts. Each group was responsible for counting and identifying as many butterflies as possible in their respective area. The butterfly count area included such hotspots as Dana Meadows, Gaylor and Granite Lakes, Saddlebag Lake, Ellery Lake, Warren Canyon, Hall Natural Area, lower Lee Vining Canyon, Mono Lake County Park, and Lundy Lake.

The weather that day was predictably stormy, with intermittent showers occurring after 11 am. Butterflies typically don’t fly in inclement weather, and the butterfly counters had to be extra savvy to find any butterflies at all. They systematically searched all habitats for species that specialize on specific plants, varying degrees of moisture, and that exhibit different behaviors at different times of the day or under different conditions. All the while, each person had to be completely focused, conjuring a particular search image, depending on the conditions, circumstances, and target species. The leaders were not only adept at identifying species, but also enthusiastic teachers, helping the other participants learn all sorts of facets of butterfly identification and ecology. After several hours of intermittent rain and distractions with finding amphibians and wildflowers, a fun and impromptu meeting occurred at a local coffee shop.

Undeterred by the rain, the group reconvened back in Tuolumne Meadows to share highlights from the day, report count results, and enjoy pizza. Lepidopterist, author, poet, and founder of the Xerces Society, Robert Michael Pyle, led the compilation, while sharing entertaining butterfly stories, and facilitating lively discussions about difficult species identifications.

The final tally for the day proved decidedly good, with an unexpected high species count considering the stormy weather: a total of 40 butterfly species composed of 680 individuals. Really extraordinary was having 41 participants, almost a one-to-one ratio with the number of butterfly species! With so many eyes alert for butterflies, unsurprisingly were some great natural history moments and highlights. The 3 most frequently detected butterflies were sandhill skipper (133 individuals), Shasta blue (102 individuals), and greenish blue (72 individuals). Of all the species detected, 4 were new species (Becker's White, Sylvan Hairstreak, Reakirt's Blue, and Common Checkered-Skipper) never before observed during a Yosemite Butterfly Count.

Highlights were many. One party hiked almost a vertical mile though a boulder field to successfully find 45 heather blues. Several people observed butterflies “sleeping” in the rain. The number of “blues” (255 of 11 species) far outnumbered the number of fritillaries (66 of 3 species). One group discovered 8 zerene fritillaries inhabiting Warren Canyon (having not flown up from lower elevations). The combination of the butterflies themselves, people brimming over with natural history knowledge and passion, and beautiful scenery makes this one day very special. As Liam O’Brien put it, “the Yosemite Butterfly Count quickly has become Centre Court/Wimbledom of the California Butterfly Count Season.” See you at next year’s count on July 27, 2015!

Related Information

  • View raw data results from 2011-2014 [35 kb PDF]

  • Check out an entry (includes photos) from our High Country Notebook Blog related to the 2012 event.

  • Interested in other annual events to help you connect with your inner naturalist? Each year, tens of thousands of volunteers across the Americas join together annually during the Christmas Bird Count. The event provides a full day to celebrate birds. We take part here in Yosemite - learn more!

2014 Butterfly Count participants

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