Butterfly Monitoring Program: 2020 Survey Trends and Observations

Cold weather in spring 2020 coincided with reduced detections of butterflies.

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2020 marked the fifth season of butterfly surveys at MPG North since 2014.

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Since 2014, Common Wood-Nymphs (Cercyonis pegala) and European Skippers (Thymelicus lineola) have been numerous every year.

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European Skippers (above) decreased by approximately 75% from 2019.

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Cold, wet conditions, coupled with suppressed growth and availability of host species for developing larvae, are possible contributors to the significant decreases observed in Common Wood-Nymphs, European Skippers, and other species in 2020.

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Mourning Cloaks (Nymphalis antiopa, above) can overwinter as adults, helping them better survive freezing periods in the spring.

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Generally found in low numbers each season, the number of Greenish Blue Butterflies (Plebejus saepiolus, above) was up in 2020.

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The number of greater fritillary species was up this season, with five species identified in 2020.

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2020 was a strong year for sulphur butterflies

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With only a few sightings recorded over the past three years, the common roadside-skipper (Amblyscirtes vialis, above) was abundant this season.

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Appendix: 2020 Species List

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Appendix: 2020 Species List 2

Posted on 1/15/2021 by sbradford

About MPG North

Established in 2005, the property boundary at MPG North encloses 200 undeveloped acres in Western Montana’s Swan Valley. Researchers and field staff manage the property to improve habitat quality for wildlife, discover new ways to restore damaged landscapes and study forest ecology. We also create opportunities to share what we've learned with local conservation organizations, students of all ages, management agencies and volunteers. Through these education and outreach efforts, we seek to inspire others to work together and protect undeveloped landscapes.