Butterfly Big Day 2026: HCT joins worldwide collaboration with Cold Brook field class
Hearts will be fluttering on September 12th, as a worldwide collaboration of butterfly organizations celebrates Butterfly Big Day 2026. The event is designed for people of all ages to document and learn more about butterflies and other pollinators, and how we can help their populations.
A monarch butterfly alights on goldenrod. Photo by Janet DiMattia
Harwich Conservation Trust (HCT) is joining in the global fun with a Butterfly Field Class on Saturday, September 12, from 10 a.m. to noon at the Robert F. Smith Cold Brook Preserve.
The class will be led by longtime HCT volunteers Karen and Gerry Beetham, who spearheaded the creation of a pollinator garden at Cold Brook in 2025. The cost is $20 per person and registration is required. For more information and to reserve your spot, click here.
Participants will also learn how to identify different butterflies, discover fascinating facts about their life cycles, and how native plantings can attract them to yards and gardens.
A global ‘butterflying event’
Butterfly Big Day 2026 is billed as a “butterflying event,” where people from around the world can contribute to the effort by submitting their butterfly photos to iNaturalist, a nonprofit social network of biologists, naturalists and citizen scientists who share observations of biodiversity.
Gerry Beetham is well-versed in iNaturalist and will be reporting the data from the Cold Brook event.
Partners for Butterfly Big Day 2026 include organizations located in the United States, Australia, Brazil, Canada, Europe, Honduras, Kenya, New Zealand, Taiwan and Uganda.
The effort is being coordinated by the Urban Butterfly Initiative, an Illinois-based nonprofit that uses butterflies as an “ambassador to nature,” and works with partners who seek to increase biodiversity, beauty and scientific awareness in their communities.
Monarch butterflies have become frequent fliers at HCT’s Cold Brook Preserve.
Cold Brook rewilding effort provides habitat for butterflies
Karen and Gerry used to do their field class at Thompson’s Field Conservation Area. But the venue was changed after HCT completed an ambitious partner-driven eco-restoration project at Cold Brook, which added a half-mile All Persons Trail, restored 44 acres of wetland and a mile of stream habitat.
Now home to all kinds of wildlife and flourishing native plants, the area has become a popular hiking and nature-watching destination–and the butterflies like it, too!
“As the Cold Brook restoration was finishing up, I saw butterflies there that I hadn’t seen before, like common buckeyes and clouded sulphurs,” said Gerry Beetham. “And I thought, how wonderful is this? We’ve got host plants, we’ve got nectar plants, and we’re attracting these butterflies.”
Gerry was asked if he had a favorite butterfly. “No,” he replied. “I love them all. Well, maybe it’s the one that’s right in front of me at any given time.”
Butterflies to BioBlitz
A very hungry monarch caterpillar munches on a leaf. Photo by Janet DiMattia
Butterfly Big Day 2026 shares similarities with another exciting HCT event that is scheduled for Saturday, September 19th.
The Cape Cod BioBlitz, hosted by Harwich Conservation Trust is a free day-long effort at Cold Brook that will seek to identify as many different species of plants and wildlife as possible, providing an intriguing snapshot of the biodiversity that has thrived at the Preserve since the completion of the eco-restoration project.
Volunteer BioBlitzers will sign up for a taxonomic group they are interested in looking for, and during a designated two-hour time slot, they will be accompanied by a group leader with expertise in that area.
The data will also be shared via the iNaturalist platform. To view the various taxonomic groups and time slots that are available, and to register, click here.
Late summer is a great time to be outdoors and see what nature is up to. Whether it’s HCT’s Butterfly Field Class or the Cape Cod BioBlitz (or both), we hope to see you out at the Cold Brook Preserve. Chances are, you’ll learn something new, meet some nice folks and enjoy the thrill of a wildlife treasure hunt!
Details on two great HCT events:
Butterfly Field Class
When: Saturday, September 12th, 10:00 a.m. to noon
Where: Robert F. Smith Cold Brook Preserve, 203 Bank St., Harwich Port
Cost: $20 per person, registration required. For more information and to reserve your spot, click here.
Cape Cod BioBlitz hosted by Harwich Conservation Trust
When: Saturday, Sept. 19th, from 6:30 a.m. to 10:30 p.m. (various two-hour time slots available)
Where: Robert F. Smith Cold Brook Preserve, 203 Bank St., Harwich Port
Cost: Free, registration required. To view the various taxonomic groups and time slots that are available, and to register, click here.
Falmouth BioBlitz: For folks who find it more convenient to participate in a BioBlitz on the Upper Cape, The 300 Committee Land Trust will be hosting the Falmouth BioBlitz on September 19th and 20th at the Upper Coonamessett (170 Hatchville Rd., Falmouth). For more information, visit 300committee.org.
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