Return to Houghton Lake

by Carl Strang

With the singing insect season winding down, I made a final trip of the year to Houghton Lake in north central Indiana. I had not been able to reach certain wetlands on my previous visit, but with much of my strength recovered I was able to wade through the tall dense vegetation.

The periphery of the wetland area was of good quality. There were many interspersed shrubs.

Farther in the center, the portion I explored quaked like a bog, but there was no sphagnum and I imagine it is more calcareous, over marl, and thus more fen-like. The plants were senescing, and I found no singing insects of interest in there, but it will be worth exploring earlier in a wetter year.

One highlight of the trip was a pair of black-horned or Forbes’s tree crickets I found engaged in courtship. My attention was drawn by the unusual buzzing quality of the male’s singing, which he produced whenever the female backed away.

Most of the time I watched them, she was feeding from the glands on his back at the base of his wings.

The male was relatively small and pale. The female was larger, and the darkest individual of this species pair I have seen.

Her head was black, and she had liberal amounts of black pigment on the rest of her body and legs.

These species remain active well into October, and I have wondered if the dark pigmentation is an adaptation for the late season.

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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.

Toward Singing Insect Monitoring: Wall of Sound

by Carl Strang

A few days ago I began addressing the challenges to developing a monitoring protocol for singing insects. The biggest single difficulty is, as I described, differences in peoples’ ability to hear different pitches of sounds. Frogs and birds, the other organisms monitored by their songs, vocalize well within the hearing range of most people. Not so with singing insects.

It takes time to learn to recognize the various songs, but a learning period is part of every monitoring program. Also, monitoring will need to be done day and night because different species sing at different times. Apart from these relatively straightforward aspects, there are at least two other difficulties to overcome that are peculiar to singing insects. One of these is the lack of a vocabulary for describing insect songs. This will come with time, as different people come up with creative ways to communicate. For instance, several times I have heard people likening the tick-and-buzz pattern of the generic meadow katydid song to the sound of a sprinkler set to bounce back rhythmically to its cyclic starting point every few seconds.

Carolina ground cricket, one of the contributors to the wall of sound (though not this particular female, of course).

The final challenge is what I call the wall of sound. This is especially true at night, when the greater number of species and especially of individuals all are singing at once. In particular, many of the common tree crickets and ground crickets have more or less continuous trilling songs that blend to produce a collective mass sound that seems largely undifferentiated. I have a solution that works for me, and perhaps it could be made part of a protocol. When I do my block counts at night, I count only those individual singers that are close enough for me to distinguish clearly as I walk along. I ignore the wall of sound at large. For the most part this gives me a good sample of the species producing that wall, along with the others whose songs are more easily distinguished.

Singing black-horned/Forbes’s tree cricket, another element of the wall.

This isn’t a neat and perfect solution, however. Some of the long-trilling tree crickets have songs that cannot be separated from one another by ear. Others, and I am thinking here specifically of Davis’s tree cricket in my area, usually sing high enough in the trees that their songs are completely buried. Individuals can be distinguished only on the rare occasions when their song perches are low in the canopy (in such cases the Davis’s song is low enough in pitch to stand out).

As should be clear by now, if a singing insects monitoring program is to be comprehensive, it can’t be based on point counts, as is the case in breeding bird surveys and frog monitoring. It will have to be based on a route, as in dragonfly or butterfly monitoring. In conclusion, I think the elements are in hand to produce a workable protocol for a singing insects monitoring program. The main thing missing is enough people sufficiently interested that they will put in the time to learn the songs. Tomorrow I’ll suggest a learning program that will help people to learn insect songs in readily digestible stages.

Celebration

by Carl Strang

Yesterday was a day of milestones, celebration, with just a touch of poignancy. My new tree was planted.

A Hill’s oak, in its new home

As I shared last spring, the green ash in my front yard had become infested with emerald ash borers. There was no saving it, so sadly I had to let it go. As I considered replacement possibilities, my thoughts turned to Hill’s oak. I love oaks most of all among tree groups, and Hill’s oak is a species I have seen doing well in the clay soil of the savanna ridge at Mayslake Forest Preserve. Spring Bluff Nursery had the species, which they call by its other name of northern pin oak (though recent taxonomic work makes clear that northern scarlet oak would be a more accurate name), and for an extra fee they were willing to go beyond their usual delivery boundary and plant it for me. That was one cause for celebration.

The other was that Thursday was the day I completed my first full week of 3-mile runs (excepting cross-training days) since I strained my back in mid-April. It has been a long road back. Too little activity, and too much nursing of an extremely painful left side, had left me with an atrophied left leg and total loss of cardiovascular conditioning. Physical therapy, gradual resumption of core exercise training, strengthening exercises, eventually bicycling, and finally awkward bits of jogging, gradually put me on the road to recovery. I hope to run a half-marathon in the spring.

I had saved my last bottle of Central Waters Bourbon Barrel Stout for this day. Only one batch is produced each winter by that Michigan brewery, and none had been available since spring. As I finished my post-run pizza and sipped the last of that beer, I looked out the window at the new tree. It occurred to me then that this tree will be growing long after I am gone. It will shade generations of children waiting for school buses. Its brilliant autumn color will draw the eyes of passing neighbors. Such buried poignant thoughts perhaps are behind all celebrations. So here’s to oaks, to distance running, and to future generations!

Grub Control

by Carl Strang

Earlier this week a number of small, freshly dug holes appeared in scattered parts of the mansion lawn at Mayslake Forest Preserve.

The holes were small, 1-2 inches in diameter, and not very deep.

Considering the structure of the holes, their location, and the time of year, it was not a big challenge to identify them. In fact, I had seen such holes being dug one night when I was camping in Ohio in 2005.

The next day I had photographed one of those holes.

The excavator was a striped skunk, and it was after beetle grubs in the lawn. Here are my notes from that night in Ohio: “12SE05, Caesar Creek campground, southeastern Ohio. I saw much evidence of skunks in the area. In the dusk, a large beautiful individual whose broad back stripes had joined, giving it a white back with just a little black in the middle of the lower back, passed my campsite. Later in the dark, a smaller individual was digging grubs in the lawn of the adjacent campsite. This one was all black with a tuft of white on the head and another at the tip of the tail. It came as close as 15 feet, but turned away when I shined a light in its eyes. It moved slowly, sweeping its head back and forth and sniffing, but when it found something to dig it moved quickly, excavating and moving on within about 3 seconds.”

The holes at Mayslake might even have been dug by the same skunk rescued by Nikki earlier in the summer.

That skunk awaiting rescue in early July.

It can be alarming to find so many holes in your lawn, but keep in mind that the grubs could have done a lot more damage if left there. The skunk efficiently removed the grubs with the smallest of holes, incidentally aerating the lawn. The skunks strike me as being patient and economical, waiting until the grubs are big enough that they are both easy to sniff out and at their most nutritious food value. Hooray for skunks!

Toward Singing Insect Monitoring: Dominant Frequency

by Carl Strang

When I conduct workshops or lead field trips on singing insects, people commonly ask about monitoring protocols. We have well established monitoring programs in the Chicago area for birds, frogs, butterflies, dragonflies and damselflies, plants and probably other groups I am forgetting at the moment, so how about singing insects? My answer usually revolves around the fact that different people hear singing insects differently, and this obstacle is a challenge that has yet to be solved. An important variable here is that different people hear different ranges of sound frequencies, and commonly older folks (like me) lose the ability to hear high-pitched sounds. Recently I decided to try to get a quantitative handle on this pattern, using my experience as a gauge. I went to the Singing Insects of North America website and The Songs of Insects book by Elliott and Hershberger, and lifted out the dominant frequencies sung by the species in the Chicago region.

A male short-winged meadow katydid, one of the small meadow katydids, whose song has a dominant frequency of 13 kHz.

Most singing insects produce a range of different sound frequencies when they sing, a buzz for instance consisting of a mix of many low- to high-pitched sounds. Different sounds within the mix have different energies or volumes. The dominant frequency is the loudest one in a given species’ mix. Looking at just the dominant frequency, I see that the various local species range from 1.3 to 17 kilohertz (thousands of vibrations per second, a measure of the pitch or highness/lowness of a sound). I can hear every species with a dominant frequency below 13 kHz. In fact the only species I cannot hear at all are the small meadow katydids (the members of genus Conocephalus), which sing in the 13-17 kHz range. Children and young adults can hear these, I have found. A simple, if expensive, work-around is the SongFinder device.

The long-spurred meadow katydid is my marginal species, at 12 kHz. I can hear them from close range in the woods if there aren’t a lot of competing sounds. Interesting to me is the fact that I hear them clearly at the Brookfield Zoo, where they are fairly common. I doubt that the zoo’s long-spurreds have lower dominant frequencies. My best guess is that the relative lack of other sounds in that range, plus the amplification of the songs reflecting from sidewalks and buildings, increases my ability to hear them there.

Long-spurred meadow katydid, my marginal species

Another related variable is a person’s ability to pick up a sound from a distance. Roesel’s katydid has a dominant frequency of 15 kHz. I can still hear them, but less well with each passing year, and I have to be closer to them. Children and young adults easily pick them up earlier in the song and at a much greater distance. Probably what I hear is not that dominant frequency but the lower part of the frequency range included in Roesel’s buzz. Recently I learned that young adults can hear common meadow katydids, dominant frequency 10 kHz, at a much greater distance than I can, though I hear them clearly if I am within, say, 30 feet.

Common meadow katydid

I think that monitoring protocols are possible to develop, but clearly these are variables that will need to be taken into account. There are other obstacles as well, which I will address at another time.

Mayslake Birds Update

by Carl Strang

The birds have completed their nesting for the year, and some already have departed for the South.

It has been a while since Mayslake Forest Preserve’s eastern kingbirds have filled the air with their distinctive chattering.

Mayslake is not a migrant mecca, but we get a few. The mixed flocks usually build themselves around the local black-capped chickadees, whose frequent calling and local knowledge make flock cohesion possible and worth maintaining. One recent flock contained 2 chickadees, a redstart, 2 magnolia warblers, a black-and-white warbler, a black-throated green warbler, and a chestnut-sided warbler.

The black-and-white warbler crawled the tree bark, while the other species hunted insect prey in their various other specialized ways.

Another flock on the same day included a chickadee, a redstart, a house finch, a downy woodpecker, a white-breasted nuthatch, and a house wren. Resident birds like the woodpecker and nuthatch often join these flocks. A final grouping that day included 3 chickadees, a Nashville warbler, and a warbling vireo.

The Nashville warbler

September birders know to key on the chickadee calls. The migrants certainly do.

P.S., this is the 900th post of this blog.

Mayslake Insect Update

by Carl Strang

The past couple of months have provided new insects to add to the site list at Mayslake Forest Preserve. The great golden digger, a solitary wasp species in which the females dig tunnels in the soil where they provision their young with paralyzed grasshoppers, katydids and crickets, appeared at Mayslake’s flowers in small numbers beginning mid-summer.

Striking in its yellow, red and black colors, this wasp is not aggressive toward people.

Another addition was this tiger moth caterpillar humping its way across the parking lot one mid-day.

As in a cartoon sheepdog, it’s hard to tell which end is which in a static photo.

This is the yellow woolly bear or Virginian tiger moth. Probably pretty common, it nevertheless will be an addition to the Forest Preserve District’s county species list.

I was pleased to get the opportunity to photograph a live lyric cicada.

Usually these are too high in the trees to see easily.

The black collar and large chestnut patches on the pronotum (top of the thorax) are distinctive.

Lately there have been a lot of eastern tailed-blues.

These tiny butterflies don’t seem to land very often, and then seldom show the dorsal sides of their wings.

Autumn advances, and soon these colorful insects will be out of sight, wintering as eggs or other dormant forms.

Meanwhile, Back at Mayslake

by Carl Strang

Lately I have been reporting mainly on singing insect researches I have been conducting on vacation time in Indiana and Illinois. When working, though, I have continued my practice of lunchtime preserve monitoring at Mayslake Forest Preserve. The stream corridor marsh still has no standing water.

Dense grasses and river bulrushes have been transpiring all the recent rainfall.

One of the zoned vegetation rings is dominated by old witch grass, which last year was present only in a few small patches.

I have found new species there to add to my preserve lists, all the same.

Purple false foxglove plants have appeared at both the north and south edges of the marsh.

Another addition is Boltonia, the false aster.

Scattered in the dense, coarse, river bulrushes are differential grasshoppers, a relatively large species that likes wet places.

The olive-green color and black herringbone pattern on the femur are distinctive.

Up at the former friary site, the soil now is safely held together by a mix of weeds and fast-growing prairie plants.

The site on August 10

This area has its common grasshopper as well.

These appear to be all red-legged grasshoppers, a smaller and relatively weedy insect species.

I’ll be back to reporting on Mayslake more regularly soon.

National Lakeshore Wetlands

by Carl Strang

After catching the melodious ground cricket I drove to Pinhook Bog, a part of the Indiana Dunes National Lakeshore that is open to the public only on rare occasions. I hoped to find stripe-faced meadow katydids, but the bog’s public access boardwalk was bordered by little in the way of grasses and sedges. I was gratified, however, by the presence of sphagnum ground crickets.

These were the first I have found in Indiana. I have seen them only at Volo Bog in Illinois.

After lunch I returned to the place where Gideon, Nathan and I caught the marsh coneheads in early August. Gideon had relayed the news that some of the meadow katydids Nathan also had caught there were dusky-faced, one of the conservative species I had yet to find. The lead paid off.

The legs were totally green, unlike those of the familiar black-legged meadow katydid.

I caught a couple individuals to hold for close-ups.

The head of the dusky-faced meadow katydid is amber colored, with fine dots and lines of red-brown.

While wading the tall grasses and sedges I also spotted a different large meadow katydid with green legs and a beautiful yellow-green face.

Unfortunately I only saw the one, and the auto-focus on the camera frustrated my attempts at a clear photo before she flew away. Though blurred, the image provided enough information for identification.

This was another species on my conservative wetland singing insects want list: the delicate meadow katydid. So, what was so special about this place?

View of the edge of the portion of the Great Marsh under discussion.

For one thing, invasive Phragmites was absent, and cattails were limited to a few scattered plants. Grasses and sedges were the dominant plants. Black-legged meadow katydids were very few, and limited to the dry-soil edges of the wetland. The plants and katydids were zoned. Just inland from the water and mud-flat edge was a zone of shorter, finer grasses in which the only singing insects I saw were abundant slender meadow katydids. Then came taller grasses of intermediate coarseness, where the dusky-faced and delicate meadow katydids were, along with a few marsh coneheads.

Female marsh conehead

The soil became progressively less water saturated as the vegetation rings went outward. Next came a zone of very coarse sedges. The only species I saw in there was, surprisingly, a long-tailed meadow katydid (a tiny species dwarfed by the big triangular sedge stems).  Interspersed here were patches of taller grasses which contained more dusky-faced meadow katydids. This area gave me a strong image of good marsh habitat to carry as I continue to search for these insects in other places.

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