Abstract: Amid ongoing insect declines, conservation programs worldwide are working to mitigate the negative effects of habitat loss, fragmentation, and degradation Most butterfly conservation efforts primarily focus on two main strategies, habitat restoration and captive rearing and reintroductions. For these actions to succeed, land managers need to understand how conservation actions affect population dynamics of the target species. Without this information it is nearly impossible to tailor strategies to meet recovery goals. In the context of Oregon silverspot butterfly conservation, we measured the effects of habitat restoration and population augmentation on butterfly vital rates. Oregon silverspot butterfly, Speyeria zerene hippolyta, is an endangered butterfly for which meadow management and captive rearing and reintroduction efforts have been ongoing for 20+ years with little indication of long-term success. To better understand the effects of Oregon silverspot management on butterfly vital rates, we 1) measured larval survival in response to invasive grass and thatch removal, and 2) used mark-recapture methods to estimate adult survival and female egg laying of both wild and captive-reared butterflies. We found that reducing the density of invasive grasses and associated thatch, increased larval survival by 50%. We also found that wild butterflies emerged, on average, three weeks before captive butterflies were released and lived up to a week longer than captive butterflies. This mismatch in timing resulted in observations of only 15% of captive females laying eggs as opposed to 45% of wild females, suggesting that captive-reared females are contributing very little to the overall population. For Oregon silverspot recovery efforts to succeed, continued management of invasive grasses is key, as is further work to match the timing of releases of captive butterflies with flight of wild butterflies. Our work highlights the importance of evaluating effectiveness of management actions so that strategies can be refined to maximize conservation outcomes.
