Taylor’s checkerspot (Euphydryas editha taylori) Captive Rearing and Reintroduction: South Puget Sound, Washington, 2016-2017.

This report summarizes work on Taylor’s checkerspot captive rearing and translocation conducted in July 2016-December 2017. The captive rearing section borrows heavily from annual reports produced by the Oregon Zoo (Lewis et al. 2017) and Mission Creek (Curry et al. 2017) programs. A total of 7,840 prediapause larvae (5,020 wild and 2,820 captive) were produced at the two facilities with 6,965 of those (4,293 wild, 2,672 captive) surviving to diapause.

Postdiapause larval Taylor’s checkerspots were released at two existing reintroduction sites in 2017: Glacial Heritage Preserve (GHP; initiated in 2012) and Training Area 7 South (TA7S; initiated 2014). A total of 3,025 postdiapause larvae were released at GHP on 10 and 23 March. Larvae were split about equally between the main monitoring area where Castilleja hispida has been inter-planted with Plantago lanceolata, and the area due west of the monitoring area where C. levisecta co-occurs with Plantago. Our intent was to quantify oviposition across the range of available host species. On 16 and 30 March 2017, we released at total of 909 larvae at TA7S. One hundred forty-six adults and one pupa (88 females, 56 males and 1 unknown) were released at TA7S between 30 May and 2 June.

We used distance sampling to quantify daily population density, daily population size, and to illustrate the distribution of adults at four reintroduction sites (R50, SCS, GHP and TA7S), one potential colonization site (SCS2) and at R76 (source site). A total of 7,224 checkerspots were counted during distance surveys in 2017. Peak day encounter rates varied among sites, with about 60 percent more butterflies observed at R50 (0.142 checkerspots/m) compared to SCS1 (0.090/m). Rates at R76 (0.053/m for transects 1-16; 0.048/m for transects 1-12) were about one third of those at R50 and half of what was observed at SCS1. Long-term monitoring and population goals were used to assess progress at R50 and SCS1. Based solely on natural reproduction, adult checkerspots were distributed across the majority of the 25-ha monitoring area at R50, and have increased their spread annually since 2014, with 20.9 ha acres occupied in 2017, the largest to date. The peak single day abundance estimate (4,244; 95% CI: 3,488-5,165) was also the highest recorded for that site and topped all Puget lowland sites for the second straight year. This population is officially established based on the project definition and continues to expand. Checkerspots at SCS1 met criteria in 2015 based solely on reproduction, but a larval release in spring 2016 to address concerns about El Nino weather on that small population restarted the five-year assessment period in 2017. Checkerspots at SCS1 occupied 61 percent of the 20-ha monitoring unit in 2017. The peak single day abundance estimate of adults in 2017 (2,298, 95% CI: 1,706-2,944; Table 17) suggests this site handily met its Year 1 establishment goal, is on a strong positive trajectory, and on track to complete the trial period for establishment by 2021.