Under the direction of the Nature Conservancy, a group of WBA members had the opportunity to help in surveying butterfly populations on the Fort Lewis Military Reservation this year. WBA was assigned the northern most prairie which interfaced with McChord Air Force Base, off Military Road in Spanaway. This particular prairie was surveyed almost weekly from May through August. The interest in our work here was high, for I had many pilot observation and species accounts of this prairie dating back to the 1970s and 80s, when I had resided several miles away in Spanaway. Since I had frequented the prairie (known as TA7) often during those years, the Conservancy was very interested in my input of the changes of both flora and fauna that have taken place from then to the present time.

In the 1970s and 80s the central portion of TA7 was an absolute garden of wildflowers during May and June. Large numbers of two different species of Desert Parsley (Lomatium), Lupine (Lupinus), Balsamroot (Balsamorhiza), and a large variety of other prairie plants flourished. Surrounding this open area was an invasion of Scotch Broom which had consumed many acres of potential prairie land atthis time.

During the 70s and 80s large numbers of Silvery Blues (Glaucopsyche lygdamus), Boisduval’s Blues (Plebejus icarioides blackmorei), Anise Swallowtails (Papilio zelicoan); and to a lesser extent, Edith’s Checkerspots (Euphydryas editha taylori) all flew here. An occasional Tiger Swallowtail, Pale Swallowtail, Spring Azure were seen during the spring. Later in the year Great Spangled Fritillaries and Woodland Skippers were seen. On the Kinnikinnick patches Hoary Elfins were found during late April and early May.

Many changes have taken place within TA7 since the 80s. First of all, on the negative side, the central portion of that prairie that was so well colonized by butterflies is now a huge gravel pit, which seems to be expanding monthly. Thus, the best part of the prairie is lost to “progress”. Second, on the positive side, the Fort and the Nature Conservancy have worked diligently to remove acres and acres of Scotch Broom that surround this gravel pit, opening up new area for butterfly colonies that did not exist during the 70s and 80s. Three methods of Scotch Broom removal have been used: burning, pulling plants, and mowing. We noticed during our surveys that all three methods have been used on various prairies on Fort Lewis.

I was very disappointed in our survey results on TA7. The only bright spot is the Silvery Blue population which is even larger than the population I had observed during the 70s and 80s. The Boisduval’s Blues and Edith’s Checkerspots are completely gone, and the population of Anise Swallowtails is quite low compared to observations made during past decades. One must be very careful, however, in forming conclusions based on one year’s study.

Seven other prairies were also visited during the spring and summer study period. As with TA7, we were to document location, species and numbers of individuals of any butterflies we encountered. The Nature Conservancy was most interested in potentially endangered to endangered prairie species, such as the Boisduval’s Blue, Edith’s Checkerspot, Mardon Skipper, and Zerene Fritillary (Speyeria zerene bremnerii). Unfortunately, we found none of these “target” species during our survey period. We did, however, find healthy populations of Silvery Blues and Common Ringlets (Coenonympha tullia eunomia).

The Nature Conservancy is doing an outstanding job in restoring many of the prairies located on Fort Lewis. We were very encouraged by what we saw happening and the dedication these workers had to their cause. Many of the prairies that were previously overtaken by Scotch Broom are now clear and have been replanted with butterfly larval food plants. Only time will tell whether or not these restoration efforts will be rewarded with the return of the target butterfly populations.

The Nature Conservancy workers did find populations of the Boisduval’s Blue, and Edith’s Checkerspots near the artillery impact area, which was off limits to WBA members due to the danger there. Also near the impact area, a healthy colony of the Mardon Skipper was located for the first time. Later in the summer Great Spangled Fritillaries and the Zerene Fritillary were spotted at Johnson’s Prairie.

I have requested reintroduction of the Boisduval’s Blue at TA7, since lupine is even more abundant than during the 80s, but it is questionable that this will ever happen due to policies in place at Fort Lewis.

I want to thank Richard Lindstrom and Bill Yake for the great many of hours they spent with me walking these prairies during the spring and summer. I also want to thank Marty Hansen, Peter and Gavin Klein, Mary Maxwell Young and Ian Young, Cassandra Trimble, Phillip Charvet and any other WBA members that I might have omitted for helping in the study of the Fort Lewis Prairies.

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