We are collecting demographic data on populations of these frogs and butterflies that span a wide latitudinal and elevational range to encompass areas with differing environmental conditions. The goal is to see how stage-specific demographic rates (survivorship from one stage to the next – like egg to tadpole or caterpillar) vary across locations with different environmental conditions (e.g. temperature and precipitation). We can then use this information in combination with climate projection models to predict how the population dynamics of these species will be affected by climate change. This can give land managers and conservationist an idea of which species will be most sensitive to climate change and where to focus conservation efforts.
We have sites that range from the Willamette Valley in Oregon, through coastal Northern California, to the Sierra Nevada foothills near Lake Tahoe, CA. To estimate the survivorship of different life stages of red-legged frogs and Hydaspe fritillaries we are measuring egg hatch rates, and conducting mark-recapture studies with tadpoles (for the frogs) and adults (for both species). We mark individuals with a unique ID tag so that we can estimate their survivorship based on how many times we catch them again and over what period. For the frogs, we mark individuals with visible implant elastomer (VIE) tags. This is a flourescent elastomer that comes in different colors and is injected just under the skin. It is non-toxic and does not injure the animals, and it allows us to give individuals a unique tag by using different color combinations. We tag tadpoles on the tail and metamorphs and adults between the toes.
For the butterflies we catch adults with nets and write on their wings using a fine-tip sharpie marker.