Thursday, January 12, 2017

Identify Yourself!




The break between fall and spring semesters was my long-awaited opportunity to begin editing the backlog of insect song sound files I recorded last fall. It’s far more than analytical work. When I’m listening, I’m inevitably immersed in what I heard, saw, and felt as I made those recordings. I emerge feeling as though I’ve actually been back in the meadows, and it takes a few minutes to readjust to the snow and ice outside my windows. Only four months until the first Spring Field Crickets begin to sing in NE Ohio…

In going through those sound files, I’ve focused on sorting out the Black-horned Tree Crickets (Oecanthus nigricornis) from the Forbes’s Tree Crickets (Oecanthus forbesi).  They look identical and live in the same kinds of habitats, so visual cues aren’t helpful, and their exact ranges aren’t known. Doesn’t that sound like the kind of challenge I’d find engaging?

Here are two Black-horned Tree Crickets from Novak Sanctuary State Nature Preserve in Portage County, which is southeast of Cleveland. The male is singing, and the female is ovipositing. You can see the black legs and antennae, and these crickets’ heads are typically partially or entirely black.




Now here are two Forbes’s Tree Crickets. As I noted above, they have black legs and antennae, and their heads are typically partially or entirely black.





The only way to tell them apart is to measure the number of sound pulses per second in their songs. A pulse of sound is generated when a singing cricket closes his wings, engaging the file on one with the scraper on the other. (“Closing” doesn’t mean “lowering – the wings are still raised.) The number of pulses is measured against the temperature at which he is singing in order to get the “pulses per second.” 


You may recall from other posts that crickets and katydids sing higher and faster when it’s warm and slower and lower in cooler temperatures. Therefore, pulses per second will be affected by temperature: there will be more pulses per second at 78 degrees than at 68. 

Got it? I promise it won’t be as tedious to read this post as it is for me to count all those pulses per second on my sonograms. 


Now for the song comparison.

The first recording is a Black-horned Tree Cricket on 9-22-16 at Novak Sanctuary State Nature Preserve in Portage County, which is southeast of Cleveland. He’s singing at 47 pulses per second at 72.5 F. I’ve highlighted a one-second area of the sonogram.



The next recording is a Forbes’s Tree Cricket from Bath Nature Preserve in Summit County, which is south – but not southeast – of Cleveland. He was an old guy who was getting a little creaky when I recorded him in his goldenrod on 11-1-16. He’s singing at almost exactly the same temperature – 73 degrees F – but he sings at 59 pulses per second. That means there are more wing strokes per second in his song, and to my ears, it sounds a little denser or more concentrated. (You can also see in the sonogram that an occasional wing stroke isn’t as strong as the others. Remember, tree crickets in early November are elderly!)




So who lives where, and what’s the actual overlap zone? Is the Forbes’s moving east, or have they been here all along? Do the two species coexist, or does one replace the other? And if it’s changing over time, what’s the baseline as of now?

Forbes’s Tree Crickets had been documented as far east as the Sandusky Bay area on Lake Erie’s central Ohio shore and also in the Columbus area. Now I’m documenting them here in NE Ohio. I go through the pulse-counting process for all the Black-horned/Forbes’s I record at a specific location, then enter the data in a graph for that particular place. 


Dr. Thomas Walker, entomology professor emeritus at the University of Florida, created a graph on which a Forbes’s or Black-horned’s song can be placed by pulses per second at a given temperature. The upper line would be the Forbes’s, as they sing at more pulses per second at a given temperature. The Black-horned Tree Crickets would fall along the bottom line, as their songs have fewer pulses per second at the same temperature. In my graphs, the upper line is orange and the lower line is blue.

So far, I’m finding Forbes’s Tree Crickets east along the Lake Erie shoreline counties and a little inland all the way to the eastern edge of Lake County and into Geauga County. Here are three examples:

Lake Erie Bluffs, below, is near the Lake/Ashtabula County line. I have only recorded Forbes’s Tree Crickets there, and this chart shows five of them.


I recorded only Black-horned Tree Crickets at Novak Sanctuary/State Nature Preserve in Portage County near the Summit and Geauga County borders.


At Bath Nature Preserve, which is the location of the University of Akron Field Station, I found both Forbes’s and Black-horned Tree Crickets. Some crickets’ songs fell in between the two. I had no idea when I recorded them that both species were present!



(These two crickets are from the Garden Bowl wetland at Bath Nature Preserve. He is a Forbes's and she could be as well.)






There isn’t too much time to gather data, as these crickets mature in early August and their lives end when freezing temperatures arrive. I can record at night while nights are warm, but these crickets sing only in the afternoon when days get shorter. As adequate warmth becomes increasingly unreliable, I bring some home to warm terrariums and record them at a constant temperature right here.

Take this old guy, for example. He was already a senior when I brought him home, but he was still singing quite a bit. You may be able to hear - and perhaps even see in the sonogram - that his song wasn't as rich and full anymore and he sounds rather crackly and creaky. Apparently, this did not diminish his attractiveness in the terrarium.






I decided to bring a female home for him, and did they ever hit it off! They were together all the time, often sharing the same leaf. It almost looked like an autumn romance. 


But they were old, as I said. After she died, I brought home another female. Within 15 minutes, their courtship was underway. 

 


I didn’t think he still had it in him. He died a few days later, though she lived for another few weeks.

I had two other Forbes’s males as well. The one who lived in a kitchen terrarium near the refrigerator instead of in the dining room had a rich, strong song that sounded like he could have been younger, though I have no idea if that could possibly be true. (Some human singers “keep their voices” later in life. Could something comparable be true for crickets?) 

      
     (Yes, that's him. I brought him home from Lake County.)





I think what I’ll try to do next year is have a Forbes’s, a Black-horned, and a Four-spotted in separate terrariums here so that I can really working on refining my listening skills! In the meantime, here is my work-in-progress Google map of Forbes's and Black-horned Tree Crickets in northern Ohio. Purple is Forbes's, orange is both, and blue is Black-horned.



I just wish I didn’t have to wait until next August to record more of them!


Many thanks to Neha Reddy, who made it possible for me to enter all these cricket songs using Dr. Walker’s regression lines.

Sunday, December 18, 2016

Large Presence in a Tiny Exoskeleton




Who would have guessed? 


The last cricket in the house this year should have been ground cricket, or possibly a Broad-winged Tree Cricket.

But this tiny individual? 



 Shortly after midnight on 12-17-16, he was singing like it was August. 




This feisty little cricket is a Handsome Trig (Phyllopalpus puchellus), and he has already lived about two months beyond his life span outdoors in a blackberry/grapevine tangle or in a shrub. I had positioned his little singing cage between the heat vent and the portable radiator, and the temperature must have been perfect.



I’ve written about these little beauties, their curious name, and their expanding range in 2014 and 2015, and you can read more about them by looking up Handsome Trigs on the right sidebar of this blog. 


So what’s different this year? 


The past several weeks is the longest period of time I’ve spent with trigs. I also had three of them in the house - one from eastern Cuyahoga County and two from Erie County – so I was able to compare the songs and behaviors of three individuals.  


A single Handsome Trig is surprisingly loud, especially for such a small individual. Although I enjoy having crickets in my little studio, sometimes a trig’s song can be too powerful to concentrate on my work and I’ll have to move him to the dining room or kitchen.


I’ve emphasized that their songs are much louder than those of ground crickets. Tree Crickets seem louder, but we humans also hear them very well because their pitches are significantly lower. Their songs are in the range of many bird songs, which is also a range that many of us simply hear better, especially as we get older. Handsome Trigs sing at 7000+ Hz, which is higher than many ground crickets but below most of the katydids. 


So how powerful are their songs? When I record ground crickets, I never need to lower the input level on my recorder. If I’m very close to a tree cricket, I’ll need to lower it a little. This little guy? I recorded him in the warm, quiet bathroom last night, and I had to decrease the level to minus 9 to keep the indicator light out of the red zone. 


While a Say’s Trig has a very smooth song, the Handsome Trig’s will sound scratchier or more crackling to us. It varies with the temperature, sounding smoother when the insect is warmer. I think of it as sparkling rather than crackling, and I find it delightful. 


Here are two Handsome Trigs singing next to each other, so they are at the same temperature (usually 68 degrees in our house).



Now let’s add the third one.  This is quite a nice little chorus. There are moments when you’ll be able to pick out one of the individuals, and other times when they will all blend perfectly. (There is also a tree cricket singing in the kitchen now.)



When I made this recording, all three singing cages were close together in the center of the dining room table. Dmitri, as usual was monitoring his beloved crickets.
 


Although this story is part of my “Tales from the Terrariums 2016” series, I can’t really keep Handsome Trigs in terrariums. These are tiny, acrobatic escape artists! They can squeeze right through a typical terrarium screen lid and will gladly do so. 



What about one of those plastic insect carriers? That should work, right?

Well, no, as I learned through experience a couple of years ago. How did he get out? Look at the space by the handle – it was just large enough for a trig, and easily accessible to an insect who can (and will) climb up anything.




It takes mesh fabric to keep them inside. In addition to safety, the other benefit for them is that they can climb it and even sing from it. When the heat is on, a trig can position himself on the side of his singing cage that is closest to the heat vent for added warmth that flows in through the top and the sides.

(For additional information on singing insects at home, I’d recommend “Singing Insects as Pets" from The Songs of Insects by Lang Elliott and Wil Hershberger and the chapter in John Himmelman’s Cricket Radio entitled “Assembling Your Cricket Radio.”)


Caring for them presents challenges. Not only are they small enough to easily escape and disappear, they are also the most impressive jumpers that have ever lived in this house. They seem to pop straight up like fleas or springtails. Often I don’t even see the jump - just the relocation. I've decided the movement is too fast for my eyes to register. 


While removing the singing cage lid, a trig can – and occasionally will – spring right out. I therefore work on an open surface – the kitchen counter - so I can see if he suddenly lands somewhere unexpected. We’ve gotten used to each other by now, though, so I find I often know how, when, and where he will move. He is also increasingly likely to simply step aside and wait for his fresh produce to descend. 


Since I haven’t kept Handsome Trigs in the house for more than a week in the past, I wasn’t certain what foods would most appeal to them. I set up the inside of the singing cages like “small plates,” and this has worked quite well.




I found organic Romaine lettuce to be acceptable – it’s a little softer and more leaf-like than iceberg lettuce. Fortunately, we live in an area where we can get organic lettuce, as pesticide residue can kill crickets. I drip water on his lettuce and rinse the mesh lid of his singing cage to provide moisture.



Ground crickets thrive on dry cricket food, and the Handsome Trigs nibble on it as well. All three trigs have absolutely loved the yellow water cubes (Cricket Quencher by Fluker) that provide a safe water substitute. Both the dry food and the water cubes are served in tiny medicine bottle caps left over from cat pills. 




Handsome Trigs seem to like tiny apple slices best of the various fruits I’ve offered. The apple is also a nice place to just hang out for a while as well. 


Grape halves are welcome, especially after they’ve been out for a few hours and have gotten soft.




I learned over time that if I place a couple small pieces of lettuce and maybe a small blackberry leaf in the singing cage, the trigs enjoy crawling between them. They sometimes choose to sing there as if between leaves on an actual plant.



In the wild, Handsome Trigs do not typically sing in the open. I may spot a trig on a twig or stem, but it likely will be a female. Males are usually on the underside of a leaf. If the leaf is folded or curled, so much the better. I have even found them in a fallen leaf on the ground, still singing from underneath or within a rolled-up hiding place. 


Only one Handsome Trig remains now, and he shows no signs of slowing down. He sings for hours as long as he’s warm. He explores his fresh food from the second I place it in his cage, and he jumps as impressively as ever.


Here he is on December 17th, singing in the warm, quiet bathroom away from cats, the grumbling refrigerator, the computer going through its backup, and the ticking kitchen clock. The furnace blower had just completed its cycle.  


His song was so powerful that I kept lowering the recording level until I reached minus nine to get out of the red zone. 




I could listen to him for hours.


In return for extra heat and a buffet of appealing food, I’ve been rewarded with the opportunity to study a tiny, fascinating cricket up close over time. Best of all, I am still hearing his cheerful, sparkling song resonating through the house even as temperatures drop into the single digits and wind-driven snow adheres to the windows.