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Butterfly Counts

Annual North American Butterfly Count

Pearl Crescent Butterfly
Photo: Rachel Mackow

The North American Butterfly Association’s annual butterfly count occurs each summer to understand the geographical distribution and relative population sizes of butterfly species throughout North America.

Every July since 2012, FoHVOS staff and volunteers walk our meadow trails at Ted Stiles Preserve on Baldpate and Thompson Preserve to tally all observed butterflies and caterpillars. Participants also assess weather and habitat conditions that affect butterfly populations and survey results.

Across both preserves we counted 1,498 butterflies representing 47 species! Common species include Cabbage White, Eastern Tiger Swallowtail, and Pearl Crescent. We are able to support a diversity of butterfly species by maintaining wildflower meadows and protecting host plants like milkweed for Monarchs and hackberries for Hackberry Emperors. Much of our work involves invasive plant species removal, deer exclosure fences to eliminate browse, and ecologically-based mowing regimes. Check out a summary of our butterfly count results below!

Want to participate in the next butterfly count?

Contact Senior Land Steward, Beth Craighead.

Proportion of butterfly families observed on FoHVOS preserves from 2012-2021. © NABA NJ Chapter
In general, more butterflies were counted at Thompson than at Baldpate. A record year was in 2016 when 243 butterflies were counted!
Thompson had a higher diversity of butterflies than Baldpate, with an average of 39 species per census year.

More information about annual butterfly counts can be found on North American Butterfly Association.

Tally the Valley

Butterflies you observe at any time in the spring and summer can be entered on iNaturalist as part of FoHVOS’s Tally the Valley project! Not familiar with butterflies? Check out our guide of butterfly species local to Hopewell Valley!