Monday, September 5, 2016

Lost and Found




Last year at about this time, I wrote a post titled, “Has Anyone Seen Me?” It was about the Dusky-faced Meadow Katydid (Orchelimum campestre), a wetland species I’d searched for year after year but had never found in Ohio.



Until just recently - specifically, August 23rd.



I knew there were historical records of this species and it appears to have been somewhat common in Ohio. However, Ohio has also lost 90% of its wetlands, and most of what remains is degraded by invasive phragmites and narrow-leaved cattails. 


I’d also written in my post that I thought I’d need to observe these katydids closely in order to learn about their behavior and where they live. 


Wendy and I had a brief introduction to them at Kingsbury Wildlife Area in NW Indiana last year. Carl Strang, who has been doing a 22-county Orthoptera survey in NE Illinois/NW Indiana for years, was our guide when we visited his area last Labor Day weekend. He knew right where to go to find them.


This year, the three of us were joined by Wil Hershberger, co-author with Lang Elliott of The Songs of Insects, for a 5-day exploration of Carl’s area and the crickets and katydids he has found in his region. It was a fascinating trip with companionship as excellent as the insects we found. As Wendy and I headed back to NE Ohio, I felt I was in a stronger position to search for additional singing insects that might possibly be in our area.


It was clear that the first thing I’d need to do is search wetlands that still had native plants, and I’d need to wade out into the water. Since I’m studying the crickets and katydids at Bath Nature Preserve in Summit County this year, I promptly headed for one of the ponds within a couple of days after returning home.


The Garden Pond is not invasive-free, but there’s lots of arrowhead at the edge of the water with other native plants as well.


I started wading into the arrowhead, periodically checking the tops of my rubber boots. I thought I heard a pattern of tics and whirrs that was different from the typical boisterous Black-legged Meadow Katydids that seem to inhabit any damp or wet area in NE Ohio. 

I looked down at my boots: water ½” from the top…



...and there in the arrowhead was a Dusky-faced Meadow Katydid! And then another!



My dilemma, as always, was: record first, or photograph first?



But it wasn’t a problem, as they weren’t going anywhere. These katydids were surprisingly tolerant of my standing in their marsh. Of course, I couldn’t move very quickly, either, as it was dark and my preference was not to fill my boots with water or get stuck in the mucky bottom of the pond.



So I remained relatively stationary, watching and listening. Eventually I saw a few more of them. When I slowly moved to the other side of the pond, I found three or four more – but only when I had waded out into at least a few inches of water. 




I was delighted!


As I wrote last year, their songs are indeed quite loud. It just doesn’t seem that way because the frequency is so very high for human ears. My recorder shot into the red zone, yet my perception was simply that I could hear this katydid better than I thought I would. I couldn’t back up very well, as I was rather embedded in mud by now, so I quickly pulled back my microphone until I could adjust the input level.
   


I could later see that the song was well over 15 kHz (that’s 15,000 Hz, and the threshold of human hearing is about 20,000 for young ears). Wil confirmed for me that the peak frequencies of the Dusky-faced he recorded were 16.3 -17.7 kHz. 

The pattern of "tics" is irregular, and the "whirrs" (or trills) are of varying lengths. Here's another example from Garden Pond. 




When I returned the next night, my initial little group now had six individuals, all on arrowhead. When they jumped, I could hear the sound of their feet hitting the tough, thick leaves. They not only perched on these leaves and stems, but were eating the leaves as well.

 

One of the females hopped from a leaf right onto my hand as I was recording a singing male. Perhaps she remembered how much she’d enjoyed nibbling on my skin during our photo shoot the night before. 


Katydids do like to nibble on human skin, but it’s usually just the lightest tickle. Not with this girl, though. I guess it takes more power to chew that tough arrowhead, and I felt sharp little pinches up and down my arms and hands as she explored and I recorded. Did I care? Absolutely not!



I visited the pond three times that week, watching their behavior, noting what plants they were on and how close to the water they stayed, and also observing how dusky their dusky faces were or were not.




There was considerable variation. Some are much darker reddish-tan while others are light tan to almost green. All have interesting wavy lines and spots that remind me of capillaries. Here are some of their faces:










 


 



The cerci are bright yellow, and the wings are brown and quite long. Their eyes are tan with a touch of orange, unlike the bright, red eyes of the Common Meadow Katydids, and their legs are green with a little brown toward the back. 




Compare their subtle shades to the yellow and black legs of this colorful Black-legged Meadow Katydid (Orchelimum nigripes) I found at the same location (photo below).


Katydids in the genus Orchelimum are larger than those in the genus Conocephalus, which includeds our very common Short-winged Meadow Katydids and Slender Meadow Katydids. The Dusky-faced Meadow Katydids seem  comparatively substantial even to some of the other Orchelimum members, perhaps in part because they stay calmly in place rather than rapidly leaping from leaf to stem to somewhere out of sight.



They are uncommon, relatively inaccessible, elegant, and - fortunately for me -  tolerant of respectful humans.





This past week, I checked the Garden Bowl wetland, also at Bath Nature Preserve. The preserve had previously been the Raymond Firestone estate before its purchase by Bath Township in 1997, and the wetland was drained in the 1930s for use as a polo field. How excellent that this wetland has recently been gloriously restored! (You can read about the process here.)

I wondered if there was any possibility that it might have had a remnant population from before the destruction. I wasn’t too hopeful, but the area is now quite gorgeous with all its native plants, water, and wildlife. Why not go down right to the water and check? I could see there was arrowhead there, too…


I searched at dusk, and didn’t find any. I waited for darkness, and continued to search. And then – there was a Dusky-faced! 


I found a second one shortly thereafter. I imagine there were more, but I couldn’t guarantee that I wouldn’t lose my boots in the mud below the water. 


But how exciting! Had they been there all along? Did they somehow move in from the Garden Pond? Are there more out at the much larger Bath Pond in areas that are not accessible? 

And maybe, just maybe I’ll find them in other northern Ohio wetlands as well. I now have a better idea of how and where to search. Perhaps I’ll even find one of the other even less common katydid species I have yet to find in Ohio. That’s where I’ll leave the story for now, but you know it will be continued next August!
 



Saturday, August 13, 2016

Spot Check




Narrow-winged Tree Crickets (Oecanthus niveus) are a common singer in NE Ohio. I know them well. I’ve found them singing between two leaves in many small trees, lower down in larger ones, in vines and shrubs, and even occasionally in meadow vegetation. 

 
In more urban areas such as where we live, they often sing with the Snowy Tree Crickets in our yards. (In fact, I'm listening to both species outside the window as I write.) It’s easy to tell them apart, as the Snowy Tree Cricket’s short, rhythmic, chirp-chirp-chirp song is easily distinguished from the slightly longer songs of the Narrow-winged. 







Their wings do seem a little more narrow than other crickets in their genus, and they have reddish or rich orange caps on the tops of their heads. 



And then there’s the antenna spots. That’s the reliable way to tell these Oecanthus genus cricket species apart. Not that they are happy to show their little antenna spots to me - or to you. It’s a challenge to get close enough at just the right angle!
 

I haven’t been too concerned about that, though, because I know my Narrow-wingeds. The red spots on their heads are obvious enough, and when I've checked the antenna spots, they clearly curve to form either a forward or reverse “J.”

 

Davis’s Tree Crickets are another matter, however. They're not nearly as common as the Narrow-wingeds, and I don’t generally come across this species. They live up in the trees, far out of reach of anyone who wants to see them at all, not to mention look at their antenna spots. The Latin name is Oecanthus exclamationis, because the spots form an exclamation mark! But again, that’s if you can: 

a. find a Davis’s Tree Cricket
b. get one down from the trees so you can look closer
c. maneuver him so that you can see his antenna spots.


Just listening, though, shouldn't be a point of confusion. Their songs are longer with more erratic pauses than those of the Narrow-winged Tree Crickets. The Singing Insects of North America web site describes the Davis’s songs as “a melodious trill irregularly interrupted, usually briefly and often after the trill has continued without interruption for >5 sec.”

The Narrow-winged's song, however, is “a melodious trill interrupted briefly at intervals of 5 sec or less. Interruptions are not synchronized, so when several males are calling the sound becomes continuous. Easily confused with the songs of two-spotted and Davis's Tree Crickets, but trills by these species are interrupted at longer intervals and have faster pulse rates.”


This all played out in a most unexpected manner at Bath Nature Preserve in Summit County, Ohio, where I’m doing a cricket and katydid study for the University of Akron Field Station this summer. The parking area's small trees are exactly the size that Narrow-winged Tree Crickets often seem to prefer. There are two young swamp white oaks, a pin oak, a sweet gum, and what might be a crabapple, though I’m not entirely sure. 


Those Narrow-wingeds were singing up a storm in the two swamp white oaks. I couldn’t get too close to the actual singers, but I saw a couple of females that had red head patches, and the males were singing the repetitive songs of the Narrow-wingeds. It sounded a little lower in pitch than I might have expected, but I didn’t have any for a comparison. The phrasing was what I expected for Narrow wingeds. 




I took some photos shooting upward from below the singers, and declared them to be Narrow-wingeds. After all, that’s who the females were. Here are some antenna spots of the individuals I checked – I think you can see how they curve to form the diagnostic forward or reverse “J.”





Imagine my surprise when it was later brought to my attention that  the two loudest singers might actually be Davis’s Tree Crickets! 


What? No, really? But Nancy Collins, who has specifically studied tree crickets for years and even discovered a new species, encouraged me to take a closer look at my singers.


Somehow, I would need to find the antenna spots of crickets who were singing in the dark up in the trees


I wasn’t entirely committed to putting a step ladder in my little car and pulling it out in the parking lot, so I was going to have to try using my insect net very gently in the branches. I feel strongly about being sensitive to insects and returning them unharmed where I found them, so the net was going to take some maneuvering.


And I succeeded! I got the singer I had recorded, and…here are his antenna spots:



It’s an exclamation mark.


So… both Narrow-winged AND Davis’s are in these little trees! I checked some additional crickets, and I did indeed find both species, including singing males. My species confirmations came through recording a singer, catching him gently in one of my trusty Parmesan cheese containers...


...and then trying to get the right angle for an antenna spot photo.

 

And what about the songs? What I'm finding is that if both species are singing together, the Narrow-winged Tree Crickets will be a whole step (major 2nd ) or a minor third higher than the Davis’s. Here's the Narrow winged in swamp white oak #2, then at least two Davis's in swamp white oak #1 (the larger of the two). They are singing at exactly the same temperature.






 
If there’s just one species singing, though, I won’t have the benefit of comparing the pitch relationship between them.

Remember, too, that all of these crickets sing lower and slower when the temperature is a little cooler, and warmer and faster when it’s warmer. The pitch of their songs will vary even during the course of an evening as temperatures change, and I'll need to learn how the relationships change as that happens.


But now I know that Davis’s Tree Crickets don’t always sing longer songs with erratic pauses. They can sing with a steady rhythm that is similar to the Narrow-winged Tree Crickets. Here's my initial recording that you heard earlier:




They don’t have to be high up in the trees, either, though that’s their common habitat. Why do those little swamp white oaks in the parking lot please these Davis's? I have no idea.

 
In time, I hope to be able to reliably identify Davis’s Tree Crickets by ear, even if there are no Narrow-wingeds with which to compare them. But for now, this is a new - and interesting – project, and Bath Nature Preserve is the place to study the songs.