The Currency I Work in

by Carl Strang

The main focus of my research these days is traveling through the 22 counties of my survey area, seeking the singing insects that live in the Chicago region. I am building on previous years’ work, filling gaps in range maps. The currency I work in thus is county records. There are around 100 species known to have occurred here, and so the maximum total would be 2200 county records. This is not going to be the eventual result, however, because many of the species live only in limited areas within the region. For instance, last week I closed the book on the green-winged cicada.

This distant photo is the best I have so far of a green-winged cicada.

This distant photo is the best I have so far of a green-winged cicada.

I do not expect to find green-winged cicadas beyond the 10 marked counties.

I do not expect to find green-winged cicadas beyond the 10 marked counties.

They occur only in sand soil woodlands within the region. Though other counties have some areas with sand soils, I have searched them and failed to find the species. Their numbers clearly diminish at the periphery of their range. Four of these county records have been from this year.

Other species are widespread, and ultimately I expect to find them in every county. Two early season species now have filled maps as a result of my travels this spring and early summer: Roesel’s katydid, and gladiator meadow katydid.

Roesel’s katydid

Roesel’s katydid

There is learning involved in the process. Some species which historically have occurred in the area I have not yet found. Others I have found once or twice. At some point I become familiar enough with a species that I know how to find it. Then I seek it out in the appropriate habitat in the counties where I haven’t found it. The sulfur-winged grasshopper is an instructive example. This year I made a push to complete the map for this early-season species. Though I ran out of time before the end of its season, I got close.

Updated map for sulfur-winged grasshopper

Updated map for sulfur-winged grasshopper (open circles represent historical records)

Next year I will check sandy sites in two of the counties in Wisconsin, LaPorte County in Indiana, and Berrien County in Michigan. Though I suspect that sulfur-winged grasshoppers occur in every county, they are very few and hard to find away from sand soils. Though my own county of DuPage is marked, it is a clay soil county and over the many years I have lived here I have encountered fewer than 5 sulfur-wings in DuPage.

A final example is the northern bush katydid. I had heard two of these in the early summer of 2007, in woodlands in my county. I had heard none since. But a few days ago I went back to one of those sites and tried listening at night with the SongFinder, a device which reduces the pitch of sounds. Lo and behold, I discovered that Parson’s Grove at Danada Forest Preserve has a lot of northern bush katydids. I hadn’t realized that it was the deterioration of my hearing with age that had prevented my detecting them. Now I anticipate finding them in every county in the region.

So far this year I have accumulated 47 county records. I expect to end up with more than last year’s 174.

Advertisements

6 Comments

  1. Dick Todd said,

    July 21, 2016 at 1:50 pm

    You might find this book interesting. The Songs of Insects by Lang Elliott and Wil Hershberger. Enjoy your post.

    • natureinquiries said,

      July 22, 2016 at 5:48 am

      Thanks, Dick. Sadly that book is out of print; I got my copy soon after it was published.

  2. July 22, 2016 at 2:38 am

    Your ongoing study is so excellent, and I very much enjoy reading about it year after year.

    • natureinquiries said,

      July 22, 2016 at 5:47 am

      Thanks, Lisa. At some point I need to quiz you about Say’s cicadas and least shieldbacks.

  3. July 22, 2016 at 6:05 am

    Very interesting post! I enjoy observing any type of nature. I was curious if you’ve been to Illinois State Beach? I was there last week. It’s like going to another country with the geological differences compared to the rest of the area. I find many plants that don’t show their pretty faces anywhere else in Lake County.
    Good luck with your research!
    BTW – Any job openings in your department? 😉 I’d kill for a job like yours.

    • natureinquiries said,

      July 25, 2016 at 6:24 am

      Illinois Beach State Park is one of the main sites I visit in Lake County, and a number of the records for that county could not have been made anywhere else. I am retired now, but the singing insects work always was on my own time. Thanks for the comment.


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: