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.

1 comment:

  1. So little is known about spring trigs, which species was only recently described. Great contribution!