Return to Berrien

by Carl Strang

Earlier this season I scouted some new sites in Berrien County, Michigan, and on Sunday I returned to see what singing insects I could find in the early portion of the peak season. A first quick stop at Mud Lake Bog produced a hoped-for population of sphagnum ground crickets, and I was reminded how utterly teeny tiny they are.

Most of the day, and a return trip in the evening, went into a place in the eastern part of the county called Chikaming Township Park. If this were Illinois, I wouldn’t expect much from a park district administered at the township level, but this is a good and well maintained site, and it yielded a pile of county records for my study. One of these was provided by a female curve-tailed bush katydid that flew to a landing right in front of me on one of the trails.

The dark-tipped green ovipositor with this shape and proportions, along with the katydid’s overall size and the habitat, permitted the identification.

The dark-tipped green ovipositor with this shape and proportions, along with the katydid’s overall size and the habitat, permitted the identification.

After release, she hung around long enough to let me take a single usable, if not absolutely sharp, photo.

After release, she hung around long enough to let me take a single usable, if not absolutely sharp, photo.

Perhaps the most bizarre observation came as a result of the day’s odd weather. I drove through intermittent rain to get to Berrien County, and waited out the last shower before going out onto the Mud Lake Bog boardwalk. Dark clouds remained until mid-afternoon, but they slowly drifted east and the sun was revealed at 4:00 local (eastern) time. Almost immediately, Chikaming’s swamp cicadas began to sing. These generally are limited to mornings, but here they were going in the late afternoon. This site proved to have the largest concentration I have encountered to date. At one point I wandered into a song battle taking place among a trio of males in a meadow with scattered tree saplings. One allowed a close approach.

None of our other cicadas matches the swamp cicada’s heavy black coloration.

None of our other cicadas matches the swamp cicada’s heavy black coloration.

Later in the evening I was able to pick up some additional species.

Among them was this Forbes’s tree cricket.

Among them was this Forbes’s tree cricket.

The highlight of the day, though, came at another site, Galien River County Park. I had set a goal for this season of listening for spotted ground crickets, which historically have been documented in several Chicago region counties, but which I had not noted to date. Described as a forest species, the spotted ground cricket’s song to my ear is similar to that of a common and widespread species, the Carolina ground cricket. I realized that while some of the forest crickets at Galien River indeed were Carolina ground crickets, others sounded a little different. I made recordings, and listened carefully, and was pleased to conclude that spotted ground crickets were there as well.

An example of a spotted ground cricket location.

An example of a spotted ground cricket location.

The songs have a similar tonal quality and pitch range to my ear. Where the Carolina ground cricket’s song is a steady purr with intervals of added overtones, the spotted ground cricket’s song is composed of regular pulses (about 4 per second), has no overtones, and lacks the continuous steady sound.

 

Return to Cicadas

by Carl Strang

On Monday I returned to the area where I searched for northernmost lyric cicadas, as described two posts ago. I had thought I heard a swamp cicada at Penny Road Pond, and wanted to listen again to confirm it.

Swamp cicada

Swamp cicada

This time two were singing, and there was no doubt I was hearing swamp cicadas’ percussive vibrato. The observation represented a shift well to the north of my previous northernmost location for the species.

The red star indicates the previous location at West Branch Forest Preserve in DuPage County. Penny Road Pond is marked by the yellow star. The two places are around 12 miles apart.

The red star indicates the previous location at West Branch Forest Preserve in DuPage County. Penny Road Pond is marked by the yellow star. The two places are around 12 miles apart.

I don’t know of any place in my 22-county survey region that has abundant swamp cicadas. As the map shows, I haven’t documented them in many counties. In large part that is because they sing only in the morning, and I have done most survey work in the afternoons and evenings when the majority of singing insects are displaying. On the other hand, I went for many long morning bicycle rides in Starke and Marshall Counties, Indiana, and heard only widely scattered individuals. Such a thin spread prevents me from being confident about finding the swamp cicada’s range boundary in the Chicago region.

Back to Monday of this week. I wanted to employ the bicycle as a tool again, this time to see if I could extend the lyric cicada’s northernmost point beyond last week’s record. I started from Trout Park, where I had heard that individual, and dropped down onto a bike trail that took me north along the Fox River. After going 6 miles without hearing a lyric cicada I turned around and headed back. Shortly after making that turn I heard a single lyric cicada, though, giving me a new north point 5 miles beyond the one reported earlier. That was it, however, as I heard no more on the return ride.

Revised lyric cicada map. The new location brings that species’ known range within 2 miles of the McHenry County border.

Revised lyric cicada map. The new location brings that species’ known range within 2 miles of the McHenry County border.

That is as much as I will do this year to determine the possible northward expansion of these two cicadas. I will be interested in pursuing this study in the future, mindful that the thin scatter of both species will lend some uncertainty to the results.

Seeking Northern Limits: Swamp Cicada

by Carl Strang

The swamp cicada (Tibicen tibicen, the scientific name recently changed from T. chloromera) is another species whose northern range limit is within the 22-county area I am surveying for singing insects.

Swamp cicada. This species is largely black, highlighting the white patches at the anterior end of the abdomen.

Swamp cicada. This species is largely black, highlighting the white patches at the anterior end of the abdomen.

They are present mainly as widely scattered individuals in DuPage County, and sing in the morning. As my survey work this year was taking place mainly in the afternoons and evenings, I hadn’t heard any, and thought I would not. Then, last week, while on the job up at West Branch Forest Preserve, I heard one singing near the lake.

He was in one of these small trees. This habitat resembles an area at Springbrook Prairie near the south boundary of DuPage, the only place in the county where I have heard several swamp cicadas singing at once.

He was in one of these small trees. This habitat resembles an area at Springbrook Prairie near the south boundary of DuPage, the only place in the county where I have heard several swamp cicadas singing at once.

This observation not only is the latest I have heard a swamp cicada singing, it also extends the known northern range boundary.

Swamp cicada observations in DuPage County. The West Branch location establishes the species in the northern half of the county.

Swamp cicada observations in DuPage County. The West Branch location establishes the species in the northern half of the county.

At some point I will need to do more morning survey work in the southern counties of the region, to get a better handle on this species’ abundance and geography.

Learning to Identify Insect Songs

by Carl Strang

One of the obstacles to a singing insect monitoring program is the large number of various songs that need to be learned for identification. This is not really much different from learning bird songs for breeding bird monitoring, however (except that the total number of species is smaller here). Instead of being daunted by the entire process, it is possible to take the learning process in stages, beginning with the songs that are common and easy to recognize, the ones you have been hearing all along but simply didn’t have the species labels. Here is a list of a dozen suggested species to start with in the first stage: spring field cricket/fall field cricket (their songs are identical), Allard’s and striped ground crickets, snowy tree cricket, common true katydid, black-legged meadow katydid, greater angle-wing, round-tipped conehead, dog day cicada, scissor-grinder cicada, and Linne’s cicada (for more information on these species, try the tags at the head of this post).

Snowy tree cricket, one of the species on the starter list

This list and those that will follow are for northeastern Illinois and northwestern Indiana. There would be substitutions in other parts of the country (I encourage readers elsewhere to make comments here with their own suggestions). Go to reference recordings of these species’ songs, either on-line at the Singing Insects of North America website or through the CD that accompanies the Songs of Insects book. It is not too late this year to hear many of the species on this list on the warmer days, though some are finished or nearly so.

My recommended species list to focus on in the second stage of learning consists of 8 species and groups of species: greenstriped grasshopper, gladiator meadow katydid, Roesel’s katydid ( three species that sing relatively early in the season), and then later, Carolina ground cricket, Say’s trig, sword-bearing conehead, two-spotted/narrow-winged tree crickets (no need to worry yet about separating the two), and the meadow tree cricket group (3-4 species whose songs are essentially identical to the ear and will remain so).

Roesel’s katydid is a species from the second-stage list.

This list of common species either will take you to additional, though still readily available, habitats, or else require a little more of a practiced ear (which practice you got with the first species group). In particular, seek out and spend some time getting familiar with the songs of the Carolina ground cricket and Say’s trig. They need a little more effort to recognize in the field, but once you have them, they will be touchstones for many other species (much as robin songs are for learning bird vocalizations). If you are starting now, you might push the Carolina ground cricket to the first list, as it is one of the few species singing on the cooler days and evenings.

Once you have mastered the second list of species, you are ready for the more subtle distinctions needed to distinguish the songs in the third species list. This includes separating out the song of Linne’s cicada from similar songs by the lyric cicada, and in some areas, swamp and/or northern dusk-singing cicada.

Linne’s cicada

Also, by this point you are ready to distinguish the two-spotted tree cricket song from that of the narrow-winged tree cricket. Also, the broad-winged tree cricket should stand out now from other long-trilling species. In addition, you no doubt have noticed and begun to puzzle out other species that are more idiosyncratic in their distribution or smaller in numbers that you have encountered in your favorite places.

And that brings you to the fourth stage, learning the songs of whatever remaining species may live in the area you wish to monitor. For this you will need a regional guide. In the Chicago region, you can meet this need with the guide I am developing. It is available for free as a .pdf e-mail attachment. Simply request it at my work e-mail address: cstrang@dupageforest.com

As you are learning and listening, pay attention to which songs you can hear clearly, and at what distances, and which are marginal. This will inform the limitations you will need to address or acknowledge in your monitoring.

Swamp Cicada Confirmed

by Carl Strang

Two years ago I was positive that I had heard swamp cicadas at Springbrook Prairie Forest Preserve, and posted about it in this blog. The habitat and song were right. However, I had not seen any of them, failed to hear any when I checked the site last year, and doubts developed as I noticed how percussive are some songs of Linne’s cicada, our most common summer species. On Saturday morning I returned to Springbrook for another try (this cicada is mainly a morning singer). I heard a distant cicada that sounded right, and made my way to a pair of small isolated mulberry trees.

They were in a dry location elevated above the stream that was converted from a straight ditch to a proper meandering configuration a few years ago.

I came in too quickly and the cicada flushed, but he simply flew to a new perch higher in the same tree. He resumed singing, and I was able to get a good binoculars view. The swamp cicada, unlike most of our members of genus Tibicen, is physically distinctive. It is largely black, with some green about the head and brilliant white spots on the sides of the abdomen. I was able to confirm the identification, and brought out the camera.

Not the sharpest photo, but sufficient to document the identification.

As singing cicadas often do, he changed his location slightly every few songs.

Here’s a side view. Note that he has lowered his beak.

I was able to get good recordings of the songs, too. I feel confident now that I can identify this species by song. It is based on a pulsing vibrato like that of Linne’s cicada, but is distinctively percussive. Though some individual Linne’s have a hard quality to their vibrations, it is not as sharp, and the sound quality is different. To my ear, the swamp cicada’s song is reminiscent of a rapidly struck tambourine. You can hear an example at the Songs of Insects website.

The significance of this is that the swamp cicada is not supposed to occur this far north in Illinois, though it does so farther east. The swamp cicada joins other species including the broad-winged tree cricket, jumping bush cricket, and round-tipped conehead as singing insects that have extended their range to the north in recent decades. Note: older references give chloromera as the species name for the swamp cicada, but more recent ones have been calling the species Tibicen tibicen.

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