Why Research Prairie-Oak Obligate Butterflies?

Butterfly populations have declined in the South Puget Sound due to habitat loss and degradation. The largest remaining areas of critical grassland habitat and associated at-risk butterflies are located on Joint Base Lewis-McChord (JBLM). Ecostudies Institute monitors endangered and at-risk butterflies to understand population locations and distributions, guide habitat management decisions, and reduce impacts to military training. We also work closely with partners to identify gaps in knowledge about butterflies and their habitat needs and design research projects to fill the gaps.

Nine species of prairie-oak obligate butterflies have been identified as Species of Greatest Conservation Need (SGCN) in the South Puget Sound region. Seven of these butterfly species, including the federally endangered Taylor’s Checkerspot Butterfly (TCB; Euphydryas editha  taylori), have been confirmed to occur at JBLM. Each of these species is non-migratory and completes its life cycle in one year, so conditions must be suitable for egg, larva, pupa, and adult every year at each site to sustain the population. Many of these species depend on intact, low-statured grassland with diverse native plant communities. Habitat loss, fragmentation, and degradation make small populations vulnerable to extirpation. JBLM Fish and Wildlife, WDFW, USFWS, and Ecostudies Institute collaborate to manage and restore habitat for these species. Monitoring is required to assess population status and distribution and prescribe and assess restoration actions. 

Federally endangered Taylor’s Checkerspot Butterflies (Euphydryas edith taylori) adults fly in early spring, and lay eggs on non-native English plantain (Plantago lanceolata), as well as native harsh paintbrush (Castilleja hispida) and golden paintbrush (Castilleja levisecta). We monitor for presence and distribution of TCBs across approximately 4,000 acres of prairie on JBLM, including the Artillery Impact Area (AIA). In addition, our team is involved in research to understand TCB movement behavior and metapopulation dynamics.

In spring of 2025, we collaborated with WDFW biologists to map TCB female flight paths to quantify their diffusion (movement) rates in high- and low-quality habitat at Scatter Creek Wildlife Area. We showed that TCB movement rates were higher in low quality habitat, which is consistent with similar work with many other butterflies. This information is currently being used to help build a metapopulation model for TCBs. 

Federally endangered Taylor’s Checkerspot Butterflies (Euphydryas edith taylori) adults fly in early spring, and lay eggs on non-native English plantain (Plantago lanceolata), as well as native harsh paintbrush (Castilleja hispida) and golden paintbrush (Castilleja levisecta). We monitor for presence and distribution of TCBs across approximately 4,000 acres of prairie on JBLM, including the Artillery Impact Area (AIA). In addition, our team is involved in research to understand TCB movement behavior and metapopulation dynamics. In spring 2025, we collaborated with WDFW biologists to map TCB female flight paths to quantify their diffusion (movement) rates in high- and low-quality habitat at Scatter Creek Wildlife Area. We showed that TCB movement rates were higher in low quality habitat, which is consistent with similar work with many other butterflies. This information is currently being used to help build a metapopulation model for TCBs. 

We monitor for the presence and distribution of two late season SGCN fritillaries on JBLM: valley silverspot butterflies (Argynnis zerene bremnerii) and great spangled fritillaries (Argynnis cybele pugetensis). Adults of both species are active in the late season (July-September) and both lay eggs on early blue violets (Viola adunca) in prairies, though great spangled fritillaries can use other violet species as well. Though it has been many years since valley silverspots have been seen on base, we regularly see great spangled fritillaries in forest edges, along open sunny forest roads, and occasionally in the open prairie. In 2025, we also implemented phenological monitoring for nectar resources, as we suspect that nectar resources are limiting for late season pollinators and butterflies.

We directly use all of the butterfly presence and distribution data that we collect to prioritize, plan, and implement restoration activities on both large and small scales. For example, we choose healthy kinnikinnick patches occupied by hoary elfins to exclude from prescribed burns, which creates refugia and allows for faster recolonization of burned kinnikinnick patches by otherwise sedentary hoary elfins. We use similar methods for other species, including TCBs and Puget blue butterflies. We now have up to four years of monitoring data showing the lasting impacts of host patch exclusions on butterfly distribution within burned areas. We also use our data to decide which areas should be targeted for seeding and plugging of key butterfly resource plants.