Butterfly Report to the ELM Committee--Fermilab--2004Tom Peterson
December 30, 2004The diversity and abundance of butterflies and birds seen here at Fermilab continue to be a testament to the extent to which Fermilab has become an environmental refuge in the heart of one of the most rapidly developing suburban areas in the U.S. While casually watching butterflies here during my 28 years at Fermilab, and especially while more intensively surveying the butterflies for the past six years, it has been a joy to find several relatively rare (for northeastern Illinois) species, such as the Purplish Copper, Meadow Fritillary, Dion Skipper, and Gray Comma not only surviving here but thriving and moving into new areas.
Summary for 2004
One new butterfly species for Fermilab was seen this year, a Cloudless Sulphur, on June 4. Cloudless Sulphur is a southern butterfly which may wander north, usually late in the summer. In spite of the early date of the sighting, that was the only Cloudless Sulphur seen at Fermilab. The year 2004 was generally a poor year for butterflies. Monarchs were noticably scarce, and there were few Red Admirals and Painted Ladies. We did, however, have good numbers of Tiger Swallowtails, Great Spangled Fritillaries, and Meadow Fritillaries, including an early May population of Meadow Fritillaries spotted by Martin Valenzuela of Roads and Grounds. We continue to see interesting shifts in the population centers for both the Meadow Fritillaries and Purplish Coppers. Both species seem to be quite opportunistic, moving into old fields with their larval host plants and nectar sources for the adults. I conclude with a few recommendations to the ELM committee.Some highlights for 2004
Luna moths
On May 13, following a tip from people at noon who had seen a Luna Moth, I found three Luna moths, including a very fresh looking one which is pictured on the Giant Silk Moth page. These beautiful members of the Giant Silk Moth family (Saturniidae) feed as caterpillars on walnut and other trees and overwinter in a cocoon. Like other giant silk moths, they do not feed as adults and live only about a week or so. They rest during the day, usually well-hidden in the green vegetation, fly at night, and are quite attracted to lights.Bronze and Purplish Coppers
In mid-June at Fermilab, Purplish Coppers and Bronze Coppers were flying, probably the first adult generation of three in a season. Bronze Coppers were especially numerous for that early in the season. They could be found in various places around pond edges, including on the transfer hall berm just east of the reflecting ponds in front of Wilson Hall. Although Purplish Coppers were never especially abundant this year, on October 21 I went to a place where I have found them in the autumn for the past few years (near the intersection of Roads A and B, also along Road C West), and, sure enough, there was a male flying around patrolling the area and occasionally visiting the white asters. Minutes later, a very fresh-looking, brilliant orange female Purplish Copper appeared, also visiting asters. Literally within seconds, the male was on the same flower with her, he turned around so they were "back-to-back", and they were mating. I just happened to be in exactly the right place at the right time to witness one of those small but amazing events in nature. It was a great way to finish the butterfly season! Both Bronze and Purplish Coppers seem to be quite widespread and well-established on the Fermilab site and are highlights of the butterfly season here every year.Meadow Fritillaries
Meadow Fritillaries are not common in the Chicago region but thrive here at Fermilab in our open fields. Meadow Fritillaries were spotted flying in early May at the southeast corner of the Fermilab site (ELM-9 and ELM-7). Subsequent generations of Meadow Fritillaries were flying throughout ELM-9, on the eastern part of the Fermilab site. They were again abundant at site 70, an old farm yard, and could also be found in the model airplane flying field and other mowed fields with violets. For the first time, we saw Meadow Fritillaries on the western part of the Fermilab site, along Giese Road (ELM-24 and ELM-25). There appear to be four adult generations in a season, about every 7 weeks starting around May 1.Great Spangled Fritillaries
Great Spangled Fritillaries were especially common in fields along woods edges in late June. These large, orange butterflies may be mistaken for Monarchs at a distance. In flight they often appear to simply have a dark center and lighter orange fringe. When seen up close, the intricacy of their markings becomes apparent. Great Spangled Fritillaries are very fond of thistle and milkweed flowers, so patches of those flowers often provide an opportunity to see one up close. In 2004 there were many melanistic variants, with more extensive black than usual, as shown on the Great Spangled Fritillaries page.Coral Hairstreaks
In late June, Coral Hairstreaks were abundant under the power lines on the eastern side of the site (ELM-9), the usual location. The old fields on the eastern side of the Fermilab site are the only place where I have found Coral Hairstreaks.Dion Skippers
Dion Skippers were abundant in early July in some of Fermilab's marshes. They are very local, seldom straying out of their marsh home, and rather rare in northern Illinois. Dion Skippers are one of the butterflies that serve as a "canary in the coal mine" for natural areas, since they can only survive in relatively pristine, undisturbed marshy sedge meadows. Bob Lootens and I found at least a dozen Dion Skippers flying in some sedges at the south end of the A.E. Sea on the eastern side of the Fermilab site (ELM-14), and we also saw several Dions in some other places around the A.E. Sea edge. This makes two large populations of Dion Skippers here at Fermilab, the other being three miles to the west along Indian Creek (ELM-27). We are also seeing Dion Skippers in marshy areas inside the Main Injector ring (ELM-4) and Main Ring (ELM-1) where they have not been seen before. The presence of these wetland skippers are a testament to the careful and successful management of the Fermilab land by our FESS Roads and Grounds people.Sulphurs and the Little Yellow
In late August, one could see many orange-yellow Orange Sulphurs and lemon-yellow Clouded Sulphurs visiting the clover in mowed grass such as along the sides of the bike paths. These are typically common butterflies in late summer. But in late August an unusual visitor, a Little Yellow was flying among all the Orange Sulphurs in a field of clover south of the Main Ring. Little Yellows are a southern butterfly that occasionally strays north in late summer; I only see a few each year in northern Illinois.Silver-bordered Fritillaries--still not here
As was described in the 2002 butterfly report, on October 2, 2002, Doug Taron introduced 40 Silver-bordered Fritillary caterpillars to the Meadow Fritillary habitat on the east side of the Fermilab site. Silver-bordered Fritillaries did not appear there in 2003 or in 2004. Doug Taron thinks the caterpillars may have been too mature to hibernate. We would like to try a release again but were not able to do it yet; perhaps next year.A species for possible future introduction
The presence of turtlehead in some Fermilab wetlands (ELM-25) brings to mind the possibility of introducing the Baltimore Checkerspot (Euphydryas phaeton) to Fermilab. The Baltimore is not officially listed; its presence would not constrain our activities at Fermilab, but it is very much restricted to pristine wetlands containing the larval host plant, turtlehead, in the midwest, and it has declined with wetland destruction. The Baltimore is found nearby at Nelson Lake Marsh, Pratts Wayne Woods, and in a few other suburban wetlands, but not found at Fermilab. Fermilab has appropriate habitat, not only in ELM-25 but other locations as well. With some enhancement of the turtlehead population in our wetlands over the next few years, we eventually could try bringing this beautiful butterfly to our site.Northern Illinois Butterfly Monitoring Network
Two locations on the Fermilab site are being monitored for the Northern Illinois Butterfly Monitoring Network, the Dion Skipper population at Indian Creek (ELM-27) and the location along the EJ&E tracks and under the power lines which hosts Meadow Fritillaries and Coral Hairstreaks (ELM-9).Conclusions
1. My strongest recommendation to the ELM committee remains the same: we should encourage savanna-like transition zones between our prairie restorations and adjacent woodlands. With the Arbor day planting just west of the Big Woods (ELM-24 and ELM-25), we are doing exactly that.
2. Dion Skippers seem to be thriving and spreading into our sedge meadows throughout the site (ELM-1, ELM-4, and ELM-14).
3. 2004 confrims that the Silver-bordered Fritillary introduction did not seem to work. We may try that species again and/or may try other species eventually, as well.
4. Two areas at Fermilab are now being monitored as part of the Northern Illinois Butterfly Monitoring Network database, the Dion Skipper habitat along Indian Creek (ELM-27) and the Meadow Fritillary habitat along the EJ&E tracks northeast of the garden plots (ELM-9).
5. Meadow Fritillaries and Purplish Coppers, both relatively rare species in the Chicago region, are proving to be very interesting subjects for observation at Fermilab. Although very widespread and well-established on site, their locations of greatest abundance seem to have shifted over the past several years. Observations here indicate that neither species is particularly "remnant-dependent", but rather quite opportunistic in moving into new habitat with their larval host plants, even rather disturbed and weedy areas. Fermilab's management of old fields with approximately annual mowing allows the host plants (violets for the Meadow Fritillaries and Polygonum species for the Purplish Copper) to thrive among nectar sources like clover, thistle, daisies, and asters. These two species in particular will merit close observation in the upcoming years.
6. The proposed Eola Road corridor on the east side of the Fermilab site includes the following species that are limited to wetland remnants: Bronze Copper, Eyed Brown, and Dion Skipper. It also includes the only Coral Haristreak population that I have found on site and is a major habitat for Meadow Fritillaries.
7. With some enhancement of the turtlehead population in our wetlands over the next few years, we eventually could try bringing the beautiful Baltimore Checkerspot butterfly to our site.
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