In April 2001, I initiated a Long-term Butterfly Monitoring (LTBM) transect at Columbus Audubon's own Calamus Swamp. The LTBM Program is jointly sponsored by The Ohio Lepidopterists, the Ohio Division of Wildlife, the Cleveland Museum of Natural History, and the Ohio Biological Survey. Throughout Ohio, weekly from April through October, butterfly monitors walk routes about a mile long and count all butterflies encountered within 15 feet. It's like the Christmas Bird Count, only more standardized.

I visited Calamus once weekly in 2001 and 2002, walking a loop from the parking lot to the boardwalk, then around the perimeter of the wetland, on the boardwalk or walking/slogging along the connecting trail. My transect passes through a variety of habitats, and butterflies reflect this diversity, with more in sunny areas than in shade, of course.

In 2001, I recorded 32 species and 1,159 individuals; in 2002 these numbers were 34 and 1286. The most common was the cabbage butterfly, 648 and 601 individuals in the two years respectively. Okay, so it's an invasive species from Europe, and its immatures eat cabbage and broccoli, but you can say the same about me.  Some butterflies were remarkably consistent year-to-year: the spring azure went from 77 to 60, hackberry butterfly from 45 to 48 and alfalfa butterfly 48 to 47.

Others showed remarkable changes. The eastern tailed blue went from four to 25, the checkered skipper from three to 47, and the buckeye from one to 20. I'd guess this results from an increase in larval food plants. A few showed huge declines: the red admiral from 67 to four and the painted lady 14 to one. Both species have well-known population cycles.

Regarding the monarch butterfly, I found 39 in 2001 and 25 in 2002, and larvae were developing successfully on the milkweeds around the parking area. The monarch Class of '02 did okay at Calamus. (Logging on their wintering grounds continues to pose a threat.)

I have yet to find anything really unusual or spectacular. I saw a checkered white last September, but 2002 was a good year for this southern butterfly. I'm surprised to not find typical wetland butterflies and skippers besides the bronze copper. Maybe the others are there and simply haven't come within 15 feet of me.

If you are interested in the Long-term Butterfly Monitoring Program, visit the Ohio Lepidopterists' Web site or contact Dave Horn.

For a complete list of butterfly species over the two year LTBM Program at Calamus Swamp, click here.

Dave Horn is a Professor of Entomology at the Ohio State University