This is an article taken from the Spring 2022 WPC newsletter On the Edge. Read all the spring updates here.

The earliest of spring days may seem like the start of something new, but for WPC’s Taylor’s checkerspot program it’s the culmination of all of our work from the previous year with the release of thousands of individuals of this endangered species. While this event might not look like what we envision a “butterfly release” to be, it will hopefully help form a vibrant population of checkerspots at a historically occupied site, Helliwell Provincial Park on Hornby Island.

Our incredibly successful breeding season in 2021 meant that this year we had over 5,400 larvae to release. Let’s take a moment for that to sink in. We had 5,400 caterpillars, each 2cm long (which is the approximate size of a peanut) that we had to hand release into the wild one caterpillar at a time. This meant that logistically we needed to separate our releases into three different time frames. While this means a lot more ferries for staff (6 in total each trip!) it means we aren’t putting all the larva out at once, decreasing any risks, and allowing for more monitoring.

This photo series shows the scale of the Taylor’s checkerspot releases in BC. The caterpillars are only 2cm long, and must be hand transferred with a paintbrush to suitable host plants. Each release location is marked with a flag for post-release monitoring. Photos: C. Junck.

This year we were able to involve government officials, local naturalists groups and island residents, parks staff, zoo staff, industry partners, and K’omoks First Nation.
We know that for species like the Taylor’s checkerspot, 5,000 individuals will need to be released at a site for five consecutive years before we should expect to see the beginnings of a self-sustaining population. This is why our release of 5,400 larva this year is so meaningful.

Once released the larva immediately begin looking for food. At the release site they are likely to come across many appropriate species including marsh and thyme-leaved speedwell, other species of speedwell (Veronics spp.), and a surprising favorite, non-native English plantain. Once they continue their ravenous eating they will progress through a few more larval stages before they pupate and emerge into the landscape as butterflies. Adults live for about a month, to breed and lay eggs.

To ensure we have a founding population for next year, we keep some animals back at our breeding facility. Those caterpillars are entering the final larval stages and we are seeing our first pupation of our breeding animals for 2022.

With a dose of good weather, a lot of conservation science and a little butterfly luck, our efforts this year will lead to another successful release in 2023!

Andrea Gielens

Lead Biologist – Fraser Valley Wetlands Recovery Program

Andrea manages WPC’s captive breeding and release programs for the Oregon spotted frog and the coastal western painted turtle. Andrea has studied at-risk reptiles and amphibians in Canada and abroad, including a term at the Durrell Wildlife Conservation Trust in Jersey. Andrea also manages the Taylor’s checkerspot butterfly recovery program in BC.