Counting Butterflies at Lava Cliffs, Rocky Mountain National Park

Written from an article by Vishva Nalamalapu, science communication intern, Continental Divide Research Learning Center, August 2019.

Butterfly expert and project lead Stephanie Mason walks a transect atop a former glacial cirque. NPS / V. Nalamalapu.

Lava Cliffs sits 15 miles up Trail Ridge Road in Rocky Mountain National Park, a formation left by volcanic activity 28 million years ago. It seems no place for butterflies: cold, windy, with small, ground-hugging plants. Yet butterflies live here in surprising numbers.

How they cope:

• they angle themselves toward the sun;
• they shiver to make body heat;
• they shelter in warm crevices between rocks;
• and the small plants, though tiny, are plentiful.

A Rocky Mountain Parnassian on Lava Cliffs. NPS / S. Mason.

The project

Lava Cliffs is one of six sites that Stephanie Mason, senior naturalist with the Audubon Naturalist Society, has monitored since 1998. In 1997, Rich Bray, then lead investigator of the Rocky Mountain Butterfly Project, and Dr. Paul Opler, professor of entomology at Colorado State University, chose these sites and 14 others because they were accessible and spanned both sides of the Continental Divide, high and low elevations, and wet and dry habitats.

The purpose: to learn which butterflies live in the park and in what numbers. Because butterflies depend on plants — adults drink nectar, caterpillars eat leaves — their diversity also reflects the park's plant diversity, and threats to both.

Alpine sunflower, a common nectar plant on Lava Cliffs. NPS / V. Nalamalapu.

The method

Mason follows a modified Pollard count:

1. She walks a 1-kilometer transect at each site.
2. She records every butterfly that enters an imaginary cube around her: 2.5 meters to each side, 5 meters ahead and 5 meters up.
3. She notes the flowering plants within 20 feet of the transect.
4. She repeats it through the season, ideally once a week, weather permitting.

The transect (lower dashed line) and the survey cube that moves with her (upper dashed line). NPS / V. Nalamalapu.

A general naturalist, Mason often steps out of her cube to point out the camouflage of white-tailed ptarmigan, identify scat, or explain lichen colored by animal urine — then steps back in and strides on.

Identifying a Melissa arctic, a butterfly often seen on Lava Cliffs. NPS / V. Nalamalapu.

The results

• Species: the project's citizen scientists have recorded 141 butterfly species in the park.
• Trends: over 21 years, some species have declined, but none have disappeared — matching worldwide trends driven at least partly by climate change, habitat degradation and fragmentation.
• Why none are gone: an insect species goes extinct only under a catastrophic or persistent threat. So far the threats have been neither. If they continue, that may change.

Rocky's varied habitats and low fragmentation, thanks to its protected status, support everything from the Rocky Mountain Parnassian to the Melissa arctic and the Shasta blue.

Sources

Written from "Butterfly Survey at Lava Cliffs," by Vishva Nalamalapu, Continental Divide Research Learning Center, published by the National Park Service and in the public domain; rewritten in hubnx's own words.