DuPage Robust Coneheads

by Carl Strang

Last year, while conducting an evening survey drive to map fall field cricket distributions in my home county of DuPage in Illinois, I was passing through Springbrook Prairie Forest Preserve when I thought I heard a couple robust coneheads singing.

Male robust conehead in singing posture, Newton County, Indiana

Male robust conehead in singing posture, Newton County, Indiana

This was surprising, and I wasn’t able to follow up in 2012, but it was on this year’s research checklist, and on Monday evening I heard them again in the same location. I found a place to park, and to make a long story short was able to confirm my suspicion (a later sonograph analysis of the recording I made will determine whether this was a robust conehead or, less likely given the loudness of the song, a false robust conehead).

This discovery was surprising because in general I have been finding them, as researchers in past decades also have noted, mainly in areas with sandy soils.  No such soils exist outside children’s playgrounds in DuPage. On the other hand, no lesser a light than Richard Alexander listed DuPage County as a place where he had found the species a few decades ago. This is not a simple matter of latitude, as robust coneheads are abundant in sandy Lake County, Illinois, to the north. This species joins the tinkling ground cricket and spring trig as species that I have found in the county, but only in extremely small numbers in one or two places. DuPage County, out of all the 22 counties in my regional survey, is the one I have surveyed most thoroughly, and for nearly 8 full seasons. These few locally rare species are indicators that there probably will be holes in my distributional records for all counties, and so these will need to be judged accordingly. I will need to continue searching for new sites through the seasons and years, as long as I am able to do so.

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