Taylor’s checkerspot (Euphydryas editha taylori) Captive Rearing and Reintroduction: South Puget Sound, Washington, 2018-2019.

This report summarizes work on Taylor’s checkerspot captive rearing and translocation conducted July 2018-December 2019. The captive rearing section borrows heavily from annual reports produced by the Oregon Zoo (Lewis et al. 2019) and Mission Creek (Curry et al. 2019) programs. At least 9,200 eggs from wild females and 8,000 eggs from captive-bred females were harvested at captive rearing facilities at the Oregon Zoo and Mission Creek Corrections Center for Women in 2018. In all, 15,371 prediapause larvae (8,546 wild and 6,825 captive) were produced, 5,175 were released prior to diapause (Linders et al. 2019) and 9,563 (7,458 wild, 2,105 captive) surviving larvae entered diapause in captivity in June 2018.

A total of 6,561 postdiapause larvae were released at TA7S on 10, 15, and 17 March. At TA7S, 204 adults were released on 7 and 9 May. At TA15, a total of 279 adults 198 adults were released on 7, 11 and 17 May. Another relatively warm and dry spring resulted in good breeding conditions in captivity and good production from wild females, which led to release of 3,250 prediapause larvae that were in excess of what was needed in captivity were released at TA15 on 11 June 2019.

We used distance sampling to quantify daily population density, daily population size, and to illustrate the distribution of adults. A total of 16,464 checkerspot observations were recorded during distance surveys, with the greatest number observed at R50. Flight season initiation was intermediate in its timing relative to past years, with peak counts occurring on most sites 29 April-1 May. The peak day encounter rate at R50 (0.20 checkerspots /m) was about 30 percent lower than in 2018 and was comparable to SCS1 (0.22/m). At R76 (0.22/m for transects 1-16; 0.25/m for transects 1-12) encounter rates were slightly higher than in 2018. Peak day encounter rates at TA15 (0.037 /m), SCS2 (0.014/m) and TA7S (0.004/m) also increased in 2019. Long-term monitoring and population goals developed in fall 2012 were used to assess progress at R50 and SCS1. Based solely on natural reproduction, adult checkerspots effectively occupy the entire 24.8-ha monitoring area at R50 for a second straight year, having increased their spread annually since 2014. However, the peak single day abundance estimate for 2019 (5,851; 95% CI: 3,927-8,716) was 34 percent lower than in 2018. This together with the widespread dispersal observed in surrounding areas, suggests this population may be at carrying capacity. In contrast, the peak single day abundance estimate for R76 (19,435; 95% CI: 14,596-25,877), was 36 percent higher than in 2018 and the population occupied nearly the entire monitoring area. Checkerspots at SCS1 returned a peak single day abundance estimate of 5,484 (95% CI: 4,214-7,137), up 13 percent from 2018 and well above the level required to meet establishment criteria for the 3rd year running and remains on track to meet all establishment criteria by 2021. Checkerspots at SCS1 occupied 93.0 percent of the 20-ha monitoring unit in 2019, with restoration continuing across the site. Similar to R50, checkerspots at SCS1 are dispersing into surrounding habitat where colonization potential is high (e.g., SCS2).