Tinklers

by Carl Strang

After last year’s field season was done, I learned of the possibility that slow-tinkling trigs (Anaxipha tinnulenta) might be in my study region. Checking this needed to be a high priority this year, because the tink-tink-tink song of this newly described little cricket is very similar to that of the tinkling ground cricket (Allonemobius tinnulus). In fact, I had assumed that all the tinkling songs I had been hearing across the region were from the ground cricket. I sent two of my recordings from past years to Wil Hershberger, the experienced sound recordist, and he gave reason to think that these both were of slow-tinkling trigs rather than tinkling ground crickets, as I had assumed.

I began this year’s quest at Big Marsh, a Chicago Park District site where I heard tinkling songs last year. I began finding the songs, coming from dense, tall vegetation. I saw some trigs in that first spot, and did not see tinkling ground crickets, but that was not decisive because I also could hear the songs of another species, Say’s trig (Anaxipha exigua), in the same spot. The 2014 paper by Tom Walker and David Funk which described the slow-tinkling trig indicated that its general appearance is practically identical to that of Say’s trig.

In a second, more open location, there were tinkling songs but no Say’s trigs were singing. I spent a lot of time on the ground trying to spot one of the singers. Clearly they were 2-3 feet above the ground, which practically ruled out tinkling ground crickets, but I needed more. Though I never saw a singing tinkler, I caught a female trig in the same clump of plants. I photographed her before returning her, and she met the one gross anatomical separator from Say’s trig, having a proportionately longer ovipositor:

My next attempt came a few days later. I traveled to Indiana’s Jasper-Pulaski Fish & Wildlife Area. When I checked in at the site’s headquarters, I heard tinkling songs coming from some tall, dense herbaceous vegetation nearby. I made a recording but did not see any suspects:

 I went on to some woodland edges where I have photographed tinkling ground crickets in the past. Immediately it was clear that the tinkling songs there were different from the ones at the headquarters:

They were quieter, though that could have been because the singers were buried in leaf litter. More significantly, they were faster, the tinkling notes coming at a rate of 8 notes per second rather than 6. That may not seem like much, but I noticed it immediately. If anything, the temperature there was a little cooler, so if all else was equal the rate should have been slower rather than faster. There was no question that these were tinkling ground crickets, which I could see near the recorded individuals.

I went to another more open spot with tall dense vegetation where members of the slower tinkling species were singing. I made a recording, then dug in with my net. I caught two female trigs and a male, which I placed in a container to take home. No Say’s trigs were singing there, so I was hopeful. I set the crickets up in a cage, and to my delight that evening the male began to produce his tinkling song. That was the final confirmation I needed.

So far, my analysis of the sound recordings indicates that tinkling ground crickets have a faster note rate than slow-tinkling trigs at similar temperatures. The pitches (carrier frequencies) of the songs are so similar that these cannot be used to separate the species. There is another difference, however, that Wil pointed out and I can confirm. When the notes are magnified in a sonograph, those of the two species usually have different shapes. First, the slow-tinkling trig:

The largest, brightest notes are those of the trig. The shape is generally horizontal, in this case with symmetrical downward tails at each end. Sometimes the shape is a gentle, nearly flat arc with no tails. Sometimes, however, there is a lower descending tail on the right end. Now, the tinkling ground cricket:

Here there is practically no horizontal portion, the shape angling down and to the right. Sometimes the shape is sharply arched, but the right end almost always shows a longer downward tail. If you look again at the trig’s sonograph, you can see a line of smaller, more rapid notes just above those of the trig. There was an Allard’s ground cricket (Allonemobius allardi), a close relative of the tinkling ground cricket, close enough to be picked up by the microphone. Allard’s has an even more rapid note production than the tinkling ground cricket, but you can see that it shares the note shape of a downward right-hand tail.

Since those initial experiences, I have made a few dozen recordings of tinkling songs in several counties. Often note shape alone is distinctive enough to ensure an identification, but some are ambiguous enough to give me pause. I found that I need to standardize the notes, expanding them so they are 0.2 inches long on the computer screen. All of the songs coming from leaf litter on the ground have been those of tinkling ground crickets, and all of those a foot or more above the ground have been those of slow-tinkling trigs. Tall dense vegetation always has proven to house the trigs. Finally, trig songs are produced at a rate slower than ground cricket songs. All but one of the 18 ground cricket songs had note rates of 8 per second or higher. All but one of the trig songs were at 7.5 per second or lower, and 40 of the 46 were below 7. These all were recordings made at relatively warm temperatures, and higher temperatures were associated with higher song rates. At a few sites where both species were present, the difference was clear.

So in the upcoming annual revision of my guide to the singing insects of the Chicago region I will be adding a page for the slow-tinkling trig, and the site maps of these two species will show only locations for each that I have been able to verify visually or through sound recording analysis. The trigs have proven to be more widespread, and I suspect that in DuPage County, at least, they are increasing.

5 Comments

  1. jpdenk said,

    September 15, 2021 at 8:20 am

    Very interesting! I’ll be listening more closely at night now.

  2. Susan said,

    September 15, 2021 at 7:54 pm

    Thank you for putting a name to these mysterious late summer and early autumn sounds. I am still waiting to hear the Greater Anglewing
    Katydid, which I usually hear at this time of year. Perhaps it is too hot or too dry?

    • natureinquiries said,

      September 16, 2021 at 5:59 am

      They have been active for a few weeks. Local insect populations go up and down from year to year, you may have a down year in your neighborhood.

      • Susan said,

        September 16, 2021 at 9:17 pm

        Thanks! I will keep listening for them.

  3. Lisa Rainsong said,

    September 15, 2021 at 10:19 pm

    What an excellent post, Carl, and I love your photo of the female!


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