NE Ohio did not have a gentle autumn decrescendo this year.
I thought it might be yet another warm fall after the hot weather in the first
half of October, but a dramatic change in late fall brought early winter
temperatures and an end to the singing insect season that often lasts into
early November near Lake Erie. Instead of late-season field explorations, I sat
inside with crickets and katydids singing in the dining room and considered
what felt so odd about this year’s field season.
It wasn’t the crickets. All the various crickets I expected to find were present everywhere I went.
Previous blog posts have detailed my documentation of the northward advancement of Handsome Trigs and Jumping Bush Crickets. They certainly continued their steady progress into the lakeshore counties and the snow belt this year. Parts of Geauga County are even beginning to sound like Portage and Summit Counties, where Jumping Bush Crickets can obscure other members of the singing insect chorus.
Later in the season, I was able to learn a little more about the look-alike and sound-alike Black-horned Tree Crickets and Forbes’s Tree Crickets whose ranges overlap here. I’ve improved my ear training skills for identifying the two species by sound, especially when both are in the same location. The more familiar I become with them, the easier it becomes to hear the difference in the overtones of their songs.
I added a new aspect to my search this year: investigating habitat preferences for these two species.
It appears that the Black-horneds, where present, prefer edge habitat with a mix of shrubs, blackberry, and goldenrod. They seem far less likely to be in the large, open, goldenrod-filled meadows that are the typical habitat of large numbers of Forbes’s Tree Crickets. In fact, I have found Black-horneds several feet up in shrubs and small trees that are out of reach of the tip of my shotgun microphone. This can make photographing and catching them more of a challenge for a 5’3” inch human.
Forbes’s are less of a problem. I just need to be willing to push and plod through dense stands of goldenrod that are at least as high as I am tall.
I noticed a possible habitat division at The Rookery in the Geauga County park district. This park is unusual in that it supports a much higher percentage of Black-horneds than of Forbes, but I didn’t have any idea why that might be. I decided to try refining my search by observing where each species was concentrated.
How did I do this? By ear. I later checked my accuracy by recording a number of these crickets, noting the habitat and the temperature on their individual plants, and then counting the number of wing strokes per second in my sonograms
Next, I decided to revisit a preserve that had plenty of both species. The Buttonbush Trail area of Summit County Metroparks’ Pond Brook Conservation Area was an obvious choice. I’d surveyed this area for singing insects in 2013 and subsequently searched specifically for Black-horned and Forbes’s Tree Crickets in 2018.
Black-horned were somewhat more common than Forbes’s at that time (about 60% and 40%). My field notes even indicated that along Pond Brook
itself, one species was on the left side of the trail and the other was on the
right. You can hear Pond Brook in my 2018 recording of these two species - Forbes's first, then Black-horned.
I’d simply noted their occurrence at that time, but now I wanted to know why they seemed to be separated instead of mixed together. Was the vegetation the difference? I had the beginning of an idea.
It seems to be my pattern to get compelling ideas late in the season when time is short. This one was no exception, and I knew I wouldn’t have time for an extensive study. I had to begin to pursue my intriguing idea, though, so I decided to search for Black-horneds, as they are less common overall in my region.
I applied my developing ear training skills to my habitat hypothesis and recorded the ones I thought were Black-horned. In fact, I even brought three probable Black-horneds home so that I could record all of them at exactly the same temperature.
Every one of my three indoor residents and all the others I recorded in the field were indeed Black-horneds. I’d found all of them in intimidating thickets of shrubs, blackberry and young trees.
Black-horned Tree Crickets were in the blackberry, the shrubs, and a few were even in the smaller trees up to 8 feet high. Any goldenrod was mixed in with the blackberry and shrubs.
Edge habitat or clumps of shrubs and small trees in a more open area? Look for Black-horned. Wide-open goldenrod-filled meadow? It will be filled with Forbes’s as far as the ear can hear.
This isn’t a definitive discovery, of course; it’s an engaging first step that could be the beginning of my plans for next year.
But what about the katydids?
The season began with a very encouraging number of Broad-winged Bush Katydids and Rattler Round-winged Katydids. Broad-winged Bush Katydids are an expected species beginning in the first week of July.
Rattler Round-winged Katydids are occasional, and they seem to mature in mid-July. I discovered substantial numbers of them as well and felt quite optimistic about what I’d find later in July and in August.
The reality was even more troubling as a result.
It started with the Curve-tailed Bush Katydids.
I expect to find Curve-tailed Bush Katydids in strong numbers everywhere shortly after the Broad-wingeds mature, but where were they this year?
They are by far the most common of the Scudderia in NE Ohio, yet I only occasionally saw or heard even one in the counties I visited. Some species like the Oblong-winged Katydid have abundant years followed by sparse ones, but not Curve-taileds. It would never have occurred to me that they wouldn’t be widespread. What was different?
The subsequent lack of Texas Bush Katydids in August was also concerning. While there may be more individuals some years than others, I saw none in 2021 and possibly heard just one. I visited multiple parks and preserves in counties both east and west of Cleveland, yet there were no Texas Bush Katydids and only one or two Curve-taileds.
Fork-tailed Bush Katydids, perhaps? I don’t see the as adults as often as the nymphs, yet I only encountered one Fork-tailed nymph this year.
What about the other katydids that typically can be found at eye level?
The bounty of Rattler Round-winged Katydids was very brief, corresponding with the Broad-winged Bush Katydids in early and mid-July. I did not find any after this time.
Oblong-winged Katydids are more common in some years than others and I didn’t expect a large number after 2020’s outstanding season. But even in slower years, they’re always present – except in 2021.
Meadow katydid numbers were neither plentiful nor alarmingly low, though there weren’t as many Black-legged Meadow Katydids in the wet areas as I would typically find. Our ever-present Sword-bearing Coneheads did not form the usual dense wall of sound along every trail, but at least scattered coneheads were singing.
True Katydids and Greater Angle-wings were plentiful up in the trees, but Scudderia and Amblycorypha? Except for the first half of June, they simply were missing.
What changed?
Could weather have been a factor? I didn’t notice a shortage of crickets this year. When there are storms and heavy rains, both katydids and crickets seem to be amazingly resilient. There were definitely periods of hot weather, but the range of our common Amblycorypha and Scudderia extends to the Gulf Coast. (The one exception is the Broad-winged Bush Katydid, whose range is from southern Ohio northward.)
What I heard – and didn’t hear or see – reminded me of
parks I’ve studied with less singing insect diversity. These parks typically
have the arboreal katydid species and perhaps some of the most common meadow
katydids such Short-winged and Slender Meadow Katydids. There may also be at
least some Sword-bearing Coneheads, though not the typical loud and cheerful abundance
one normally finds in NE Ohio. Crickets are more common than katydids.
What I find obvious in these parks is the significant lack of bush katydids in the edge habitats, meadows, edges of wetlands.
The general deficiency this year was obscured by all the tree crickets, ground crickets, and trigs. The crickets, Common True Katydids, and Greater Angle-wings can create an impressive chorus without any bush katydids but listening for diversity quickly reveals their absence. There is a gap in the orchestral texture.
Here's an example from our backyard: the rich sound you hear is comprised almost entirely of of crickets. Only Common True Katydids and Greater Angle-wings up in the oaks are present, yet it sounds like a complete ensemble. This is to be expected in a more urban area, even when gardening for wildlife. Katydids, however, should be - and usually are - in our parks and preserves.
This was just one season. I guess I’ll need to see and hear what happens in 2022 and think through what kinds of records I should keep and how I will do this. But in a changing climate, how can I not feel uneasy?
Great information, Lisa. Here in SE Wisconsin, where I have always only encountered Forbes' (no Black-horned), there have been a few up in shrubs -- even in the middle of a parking lot. I have my fingers crossed you make some breakthrough discovery in how to tell them apart by eye!
ReplyDeleteGreat information, Lisa. Here in SE Wisconsin, where I have always only encountered Forbes' (no Black-horned), there have been a few up in shrubs -- even in the middle of a parking lot. I have my fingers crossed you make some breakthrough discovery in how to tell them apart by eye!
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