Sunday, July 23, 2017

The Sweet Sound of Confrontation




After writing about Eastern Gray Treefrogs and Cope’s Gray Treefrogs a few weeks ago, I continued to ponder my ongoing inability to actually locate and photograph them – especially when they’re singing. Was I going to have to wait until 2018 to try this again? 


I decided to go for a few evenings of after-dark walks at Orchard Hills Park in northwest Geauga County. Singing insect season would be starting soon, but I was getting impatient. I did a cricket and katydid survey at Orchard Hills some years ago and remembered how many frogs would sing in the wetland restoration area of this former golf course. While waiting for northeast Ohio’s singing insects to reach maturity, perhaps I'd spend more time with the frogs. 



The lush, recently-created wetlands were full of singing frogs, and many were the Gray Treefrogs I’d hoped to study. The walking paths include little bridges and decks that enable accessible wetland viewing. Could this possibly be a location to learn more about these resonant, but cryptic, singers?

I walked past the rowdy commentary of a Green Frog chorus near the water's edge, and they almost drowned out the Gray Treefrogs for a little while. 


You know these frogs. They're the ones that sound somewhat like snapping rubber bands, and they yelp when startled if they're on the bank when you walk past. Look at the sonogram as you listen, and you can see the exclamatory spikes when they call. 




Within minutes, a particularly loud treefrog was close enough that I thought I might actually have a chance to find one this time. My microphone is highly directional and can assist me in locating who I’m hearing, and it definitively stated that I should look in the little willows.   

 


But would he be on the trunk? In the branches? And what color would he be? Gray Treefrogs can actually change color and have a palette of possibilities between vegetation green and varying shades of gray and brown that resemble a branch …



…like this!


I was delighted! I recorded AND photographed him! The closer I studied his coloration, the more impressed I was with how he blended with his surroundings.



With that immediate encouragement, I was determined to continue looking and listening. Should I check the bulrushes and sedges next for a green individual? 


While searching, I was aware that these frogs were singing on different pitches. The highest pitch of the collection seemed to be the E that the willow resident sang. Other frogs were anywhere from a whole step to a major third lower. 


For example, listen to the lower pitch sung by this frog:




It was the song of a green Gray Treefrog in the marsh vegetation. 

 

It took considerable time to locate him in the dense texture, but I was again successful! The process of learning more about them was as exciting as actually seeing them.


There were variables in location, color, and pitch. Individual Gray Treefrogs could be either green or brown and could be singing the higher pitch, the lower pitch, or one of the ones in between. Listen:



I was clearly going to have to spend a couple more evenings here.


Before I left that first evening, I heard a very loud voice on the high pitch while walking across a small deck. Although I scanned the rushes carefully for a green individual, I could not find him. I consulted my microphone, which directed me to look straight down…

 

He was brown like the wood, and I’d been walking back and forth past this little frog while he was singing from the deck!



I came back the next night to determine whether the same frogs were still singing their distinctive pitches in the previous night's locations. They were.  


The brown one in the willows was there. 




The brown one on the deck was there, too, and he seemed to be guarding the edge of it. He sang his same pitch in different directions, but always toward the water. 







 

Was there a competitor for his territory? I heard a lower pitch coming from the vegetation near the deck,



but didn’t see anything until…


 

Now that was one imposing individual!



They sang back and forth on their respective pitches. The green one advanced toward the deck, and then climbed onto the edge! 





The brown one did not back down.



The green one advanced even farther. Though seated right on the deck near both of them, I was an irrelevant presence.


The back and forth singing was actually a full-scale confrontation. Just as with American Toads, whose distant songs sound so peaceful and lovely, close proximity revealed the true nature of those sweet pitches.



How would they reach a resolution? Should I stay, or withdraw to avoid interfering? I took some photos and left, as I didn’t want to add further stress to a very tense situation. (I’ll admit that I especially wanted to avoid any additional upset for the brown frog while he defended his space.) 


I came back a third night to see who won the deck space. The frog in the willow was still singing right where I expected. Other treefrogs sang back and forth on their various pitches, and the Green Frogs continued their emphatic discussion.



When I got to the deck, I heard the brown frog’s pitch, and I did not hear the green challenger. How could I distinguish between them? 

I've created a composite track to demonstrate. The first six calls you'll hear will be those of the brown Gray Treefrog. The second six songs are those of the green Gray Treefrog. 



The song I heard when I returned was the first one. What I saw, however, was this:



It was the brown frog, but greener now and moving between the deck and the rushes. His markings were the same, but now his color was green. 

He was still guarding his deck but his position seemed secure, at least for the moment.



I’ll end with a recording of the peaceful, meditative music of Gray Treefrogs singing back and forth, creating a delightful texture of pitches alternating in a repetitive rhythmic pattern that resonates across the pond as if the entire marsh is inhaling and exhaling. 


Funny – it doesn’t sound like territorial proclamations and belligerent threats at all!





Saturday, July 15, 2017

"Isn't It Too Early for Crickets?"




I opened my last blog post with the observation that people sometimes aren't sure if they’re listening to birds or crickets when they’re actually hearing Gray Treefrogs. This post begins with another question I was asked several times this spring by people who were aware that they were hearing a cricket. They also knew that they typically hear cricket song beginning in later July here in NE Ohio.



Except for the chirping of Spring Field Crickets, this would seem true. 




However, I’ve observed an increasing exception, especially this year. 

Let’s start where we left off in the last blog post. Imagine we’re back at the pond at the Ross County Park District’s Buzzard’s Roost Nature Preserve in Chillicothe. Remember those Cope’s Gray Treefrogs along with their Green Frog and Bullfrog chorus members? Here’s a reminder…but this time, they’re joined by today’s featured soloist. He’s right in the foreground, but listeners will often focus on the frogs and not immediately notice the cricket. 




It’s June 24th. Just who IS this? 

Spring Trigs (Anaxipha vernalis) are tiny “sword-tailed” crickets whose name comes from their subfamily name: Trigonidiinae. We commonly hear Say’s Trigs and Handsome Trigs in August and September, but Spring Trigs have been far more common in the southern two thirds of the state. In NE Ohio, it’s typical to hear a few here and there, as with this individual singing at the Medina County Park District’s Allardale Park near the Summit County border. (The temperature was warmer than in the first recording, so the pitch of this song is higher. Remember: cooler temperature = lower and slower songs and warmer = higher and faster.)



Imagine how surprised I was to hear this sound at Mentor Lagoons practically on the Lake Erie shore in Lake County!



The temperature was quite warm that afternoon, and the songs were as high in pitch as I ever hear them. They were in a small, south-facing meadow/prairie next to Mentor Marsh, which is north of the range map for this species. 

           (Range Map from Singing Insects of North America)

It wasn’t just a few trigs, either – the meadow was full of them!


I’ve been trying for a few years now to catch one for confirmation of this species’ presence. I thought it would be easy to do so with this many singing trigs. Of course, I was wrong.



The vegetation was already quite tall from the generous amount of rain we’ve had this year. Although trigs aren’t ground crickets, they certainly don't sing near the top of the grasses and wildflowers, either. Also, all our trig species are no larger than 1/4"-1/3” in size.



And can they ever jump! A trig can disappear faster than my eyes and brain can register the movement, traveling far enough to eliminate any hope of ever seeing that individual again.


I continued recording while I searched for them, and I began to notice that there were different song lengths. 




Did different crickets have specific song patterns, or did each individual cricket have more than one song length in his repertoire? Were the variations I heard triggered by conflict with other males or courtship with a female? If I could just catch one and take him home for a while, maybe I could learn more.




I had better luck locating a few females, as they were sitting in slightly more visible locations on blades of grass. 


When I actually saw a male, his athletic ability resulted in my missing with pathetic clumsiness.



Until this one.




And look at his wings! His fore wings, which are the ones he raises for singing, are the expected length. His hind wings, however, are much longer than those of other males I’d briefly encountered. He was macropterous rather than micropterous: a long-winged form who could fly. I’ve seen long-winged forms of Striped Ground Crickets, Roesels Katydids, and some of the meadow katydids, and here was a long-winged trig.


Even with his long wings, this one did not elude me. He was decisively transferred into in a mesh-walled singing cage and was on his way back to Cleveland Heights for a visit. 


As I learned with Handsome Trigs, these tiny crickets have to be kept in a container with mesh walls and ceiling because they can climb through the holes of a terrarium screen or out of the little holes along the handles of a cricket carrier. I wanted him to feel comfortable enough to sing, though, so I put the singing case inside a terrarium full of grass as high as the cage. 


He sang that first night and each night thereafter, producing songs of variable lengths like those I’d heard in the meadow. 


His repertoire also included the same series of five-second songs that I’d heard at Mentor Lagoons and elsewhere: Approximately five seconds, pause, five seconds, pause…you’ll see it on the sonogram below as you listen.





An additional pattern I noticed in the field and subsequently in the house was a short, almost stuttering start to a longer song. I’ve observed something similar in Carolina Ground Crickets when they first begin singing in the evening and also in Black-horned and Forbes’s Tree Crickets. It’s as if they’re warming up before the actual  performance  begins.


Here's a recording that begins with a song from the field immediately followed by one I recorded at home. (Remember that the difference in pitch is the result of the how warm the cricket was at the time.) The sonogram shows part of this composite recording. 




When these crickets are not singing a series of shorter songs, their extended songs can continue for 60 seconds and longer. In the field, various individuals may simultaneously sing different length songs, creating an overlapping texture similar to choral musicians discreetly breathing so it sounds as if no one has to breathe at all.



My long-winged male sang all the variants I’d heard in the field. I put the terrarium upstairs at night and kept my recording equipment nearby so I’d be ready to document his repertoire when he felt it was dark and peaceful enough to begin. We loved having him here, but I eventually took him back to his meadow. He vanished into the grasses within five seconds. 




Although their songs sound similar to the Say’s Trigs (Anaxipha exigua) who will begin singing at the end of July, their pitch is lower. Say’s Trigs may often sing at 7000-8000 Hz, but Spring Trigs sing between 4500-6000 Hz. The slightly lower pitch sounds more musical to human ears. 

Here’s a Say’s Trig singing in early September and a photo of one as well.

    (If my long-winged male Spring Trig had typical hind wings,
 they would look like the wings you see -  and don't see - on this Say's Trig)





The two species look very similar, though Say's Trigs have a pattern of dark lines on their faces. Spring Trigs are a little darker reddish-brown overall and have very dark "knees." Females are lighter than males.  

Season is the best way to separate them, and at least in NE Ohio, there's also a certain degree of habitat differenc.

Spring Trigs are residents of meadows and along habitat edges bordered by meadow vegetation. They sing from grasses and meadow plants, but I haven't heard them singing from shrubs or around wetlands.

Although Say's Trigs can be found in meadows, I can count on locating them near wetlands. They are partial to shrubs and vines, and I periodically find them sitting on poison ivy leaves. They especially love buttonbushes, and that's the first place I check for them.

I don’t know how much longer we’ll hear the last Spring Trigs, as it’s now July 15th.  Say’s Trigs are just a couple weeks away from a season of song shared with the many other crickets and katydids who be maturing soon. Spring Trigs often sing alone, but listen to the sound of early August in this recording of a Say’s Trig soloist in the foreground and Snowy Tree Crickets in the background at Lake Erie Bluffs. 
 
       (Notice that this Say's Trig is sitting on a broad leaf rather than a blade of grass. This is typical)



I’m so thankful to have had the chance to get to know Spring Trigs this year and to hear their silvery songs for weeks when it was “too early” for crickets. Will they continue to become increasingly common up here in NE Ohio? I think you probably know the answer.