Rapid extinction of several Taylor’s checkerspot populations in south Puget Sound in the late 1990s illustrated the need for a proactive approach to recovery. Habitat restoration is proceeding on several sites. The goal of this project is to establish new populations to stem decline and move toward recovery. Funding was awarded for implementation of the Taylor’s checkerspot captive rearing program in 2008-2009 and release and monitoring of Taylor’s checkerspot at field sites in 2009. A captive rearing program for Taylor’s checkerspot was established at the Oregon Zoo in 2004 and has been ongoing since that time. Large annual advances in captive propagation have resulted in high survival during all life stages from egg to adult; postdiapause rearing conditions are being refined to improve survival and weight gain during that phase; a two-year test of indoor vs. outdoor conditions was initiated in 2009. Cumulative survival from hatching to postdiapause was 91.9 percent (2522 survived of 2743 hatched larvae) in 2008-2009. This represents a significant increase in the scale of propagation efforts relative to 2007-2008, with negligible change in survival. Co-locating females with groups of males proved relatively successful as a captive mating strategy with 112 mating attempts resulting in 37 copulations; some males mated more than once. Captive propagation at the Oregon Zoo is at capacity with sufficient space and staff for about 2,000 postdiapause larvae; a second rearing facility will be established in 2010 to expand capacity and minimize risks of the captive propagation program.
A record number (2,247) of postdiapause larvae were released in 2009, with about 750 larvae released at each of three sites (Scatter Creek South, Scatter Creek North and Pacemaker Airstrip). Flight season monitoring at these sites in 2009 revealed few adults. Very cool weather until mid-May appeared to delay the flight season and is assumed to have influenced the outcome of the release, as numbers were also quite low at the source site on Fort Lewis. A total of 48 observations of adult Taylor’s checkerspots were made during distance sampling surveys (n = 7) at Scatter Creek South, with a maximum of 19 adults observed in a single survey. Just two adult checkerspots were observed at Scatter Creek North and a single adult was observed at Pacemaker Airstrip. Releases of small numbers of postdiapause larvae at Scatter Creek South in 2007 and 2008 may have contributed to the higher numbers observed there relative to the other release sites, or may indicate more suitable habitat, although this is less likely at least in the case of Pacemaker. Similar to Scatter Creek South, adults at Scatter Creek North and Pacemaker were attracted to conifer trees 40 and 100 m, respectively, from release plots; some adults may have dispersed due to low densities, a phenomenon characteristic of male checkerspots. Because checkerspot larvae are capable of multi-year diapause, we do not know whether poor flight season returns were the result of high post-release mortality, a high rate of return to diapause, or both. All release sites will be monitored again in 2010; no new releases will occur at Scatter Creek North and Pacemaker to improve our understanding of factors that may have influenced the poor returns in 2009. A fledgling population appears to be taking hold at Scatter Creek South and releases will continue there in an effort to bolster numbers and reduce risk of extinction. Adult behaviors observed at Scatter Creek South include nectaring, territorial displays by males, mating chases, routine movement patterns, and one oviposition observation. Collectively these behaviors suggest habitat recognition and confer a measure of site fidelity; the only known egg cluster disappeared prior to hatching. Habitat restoration continues in the vicinity of the release at Scatter Creek South and is expanding to accommodate additional release areas; work is also progressing at several other sites in South Puget Sound.