Tom's Notebook a summary of Tom's 2001 observations at Fermilab. . .


Tom Peterson

September Notes
One more new species for Fermilab showed up in September, the Checkered White.  This is a native American white (unlike the Cabbage White, which is a European import) and is more common to the south.  Several Checkered Whites showed up at Fermilab during September, including one at the Prairie Harvest on September 29.  September also produced, as expected, a second generation of Meadow Fritillaries at the eastern edge of the Fermilab site and Purplish Coppers near C4 in the Main Ring.  Surprisingly, I did not find another generation of Bronze Coppers.  Perhaps the large brood in August was the last for the summer, just an early final generation.  A total of seven new species were found at Fermilab this year, bringing the total seen in the past three years to 51; the table below summarizes them.
 

New for 2001 Comments
Little Glassywing Skipper A common skipper which is difficult to distinguish from several other small, common, brown skippers.
Meadow Fritillary A small remnant-dependent fritillary, rather rare in this area, a beautiful new find for the Fermilab site.
Dion Skipper A strongly remnant-dependent skipper seen at Indian Creek in the 1980's is still there!
Gray Comma This relatively rare anglewing is living in Fermilab's Big Woods (ELM-24). 
Common Sootywing A common small butterfly in open, disturbed areas like roadsides.
Variegated Fritillary This beautiful, medium-sized butterfly wanders up from the south, not unusual to find it in late summer.
Checkered White Our native, local American white, more common to the South. 

August Notes
A great summer for butterflies is continuing with a boom in the Painted Lady population.  Large numbers of these bright orange and black butterflies are visiting flowers in gardens and clover along roadsides now, in late August.  Painted Ladies are known for their periodic population explosions, and this appears to be one.  Fermilab hosts Gray Commas in the Big Woods!  This relatively rare Anglewing butterfly, which I had only seen once before, at Waterfall Glen Forest Preserve near Argonne Lab, is living in Fermilab's Big Woods (ELM-24, map).  Thus, all three Anglewings found in Northern Illinois, the Question Mark, Eastern Comma, and Gray Comma, are found in Fermilab's Big Woods.  A large number of Bronze Coppers could be found in some wet roadside areas in early August, but have disappeared now.  Unlike many butterflies, the Bronze Coppers produce another generation of adults in September, so hopefully the quantities of Bronze Coppers in early August portend another large generation in September.

July Notes
In the June, 2001, butterfly comments I mentioned that Ron Panzer, a Chicago area naturalist, reported seeing Dion Skippers along Indian Creek in the late 1980's.  Indian Creek runs through the center of the Main Injector area and south past the Batavia branch of the Illinois Prairie Path on the southwest boundary of the Fermilab site (map).  The Dion Skipper is a beautiful bright, orange-red, remnant-dependent wetland skipper.  It is only found in relatively undisturbed sedge meadows, including only a few sites in the western Chicago suburbs.  The Main Injector construction after Ron Panzer's survey, with the Main Injector tunnel excavation and road cutting right across Indian Creek,  heightened my interest in seeing whether Dion Skippers still live around Indian Creek.

The answer is yes!  In early July, following a tip from Bob Lootens regarding where the "good" areas along Indian Creek are, I found a good-sized population of Dion Skippers, especially near the southern-most part of Indian Creek just inside the Main Injector perimeter.  The skippers do not yet appear to have moved into the wetland mitigation area, a bit further north, but seem to be restricted to the remaining undisturbed parts of the wetlands.  The presence of this skipper indicates that in spite of the Main Injector tunnel and road cutting right through its habitat, enough care was taken that the areas immediately adjacent to the construction remained relatively undisturbed.   It is interesting that two other sedge meadow butterflies found at Fermilab and which I expected to find living with the Dion Skippers, the Eyed Brown and the Black Dash Skipper, do not seem to live near Indian Creek but are found in other wet areas on site where Dion Skippers appear to be absent.

June Notes
2001 is a HUGE year for butterflies so far.  Well, at least it is for some species like Red Admirals and American Ladies.  Both are more numerous this year than I ever remember.  Many other species seem to be doing well this year, such as Great Spangled Fritillaries, which can be seen (June 26) on the Interpretive Trail near the woods.

I have spotted two new species for the site so far this year--the Little Glassywing Skipper and the Meadow Fritillary--bringing the total for the site to 46.  The Little Glassywing is in an informal group of similar skippers along with the Dun Skipper that Jeffrey Glassberg (see ref. 1, below) and other lepidopterists refer to as "the witches".  Glassberg says, "All of the witches are generally common.  [Where they fly together in large numbers they can create] an unparalleled opportunity to misidentify thousands of butterflies in a single day."  If you compare my photo of the Dun Skipper with this Little Glassywing photo, you can see what he means.  I am 90% sure that my identifications of these two are correct, but I have to admit not 100% sure.

The other new species, the Meadow Fritillary, is certainly correctly identified and is a good find.  Fermilab has a colony of them living north and northeast of the garden plots, in ELM-20 (map).  Like the Purplish Copper, the Meadow Fritillary is not nationally rare, but it is locally rare in the Chicago area. At most only a few other butterfly monitors in northeastern Illinois report it at their sites. Ron Panzer and Doug Taron classify this as a remnant-dependent species. ELM-20, where the Meadow Fritillaries are found, is an old field area maintained by mowing, which is adjacent to the railroad, a power line right-of-way, and a small wetland.  Each of these could have provided a refuge for the butterflies and/or the larval host plants (some species of violets) during the agricultural years.

Mel Manner, of the Northern Illinois Butterfly Monitoring Network, reports having seen Meadow Fritillaries in some numbers for a year or two where she monitors but none before or after.  Perhaps they are somewhat mobile, colonizing and dying out from areas.  So it seems like we will have to watch this Fermilab population for a few years before concluding that it is stable.

The Little Wood-Satyr, which I only glimpsed once last year, is indeed living in the Big Woods.  I have seen several and managed to get photos of a few.  It is generally a common butterfly, but I have neither found it in large numbers nor found it outside of the woods at Fermilab, where it remains fairly well hidden.

Like last year, ELM-20 is host to Coral Hairstreaks.  I saw Meadow Fritillaries and Coral Hairstreaks on flowers together on June 24, quite a treat for a butterfly watcher! The eastern side of the Fermilab site will get a lot of my attention for the rest of this butterfly season; it may be Fermilab's best butterfly habitat.  But the opposite side of the site, along Indian Creek in the Main Injector area, will also get some attention since I have learned that Ron Panzer reported seeing Dion Skippers, a beautiful bright orange-red, remnant-dependent wetland skipper, there in the late 1980's.  Are the Dion Skippers still around Indian Creek?  I will try to find out.
 

References.

1.  "Butterflies through Binoculars, the East," by Jeffrey Glassberg, Oxford University Press, New York, 1999.

Butterfly Data - Peak Count Data for 2001 - Map of Fermilab