Waking up at the right time: Using temperature to time Taylor’s checkerspot releases

Taylor’s checkerspot (Euphydryas editha taylori) is an endangered butterfly native to the Pacific Northwest, with recovery efforts focused on re-establishing wild populations in Oregon. This collaborative project—led by the Institute for Applied Ecology in partnership with the U.S. Fish and Wildlife Service and the Greenbelt Land Trust—utilizes captive rearing at Coffee Creek Correctional Facility, followed by strategic releases at a conservation site near Corvallis, Oregon. To better synchronize larval development with conditions observed in establishing field populations, captive-reared larvae are held in an overwintering diapause, or arrested developmental state, and released based on seasonal phenological cues. However, limited understanding of temperature-dependent developmental timing presents a major constraint for optimizing release schedules. This study investigated the “wake-up” timing of diapausing larvae following removal from cold storage across a range of controlled temperatures. Our goal was to quantify how temperature affects the rate of post-diapause activation in order to better match larval emergence with ideal habitat conditions and host plant availability in the field. These results have direct implications for improving the timing of release events in conservation programs. By refining our understanding of Taylor’s checkerspot phenology under variable thermal regimes, we can enhance post-release survival and establishment success in reintroduced populations.