One Last Look Back

by Carl Strang

My recent blog posts have shared highlights of this year’s field season, as I searched for singing insects in the 22-county area I define as the Chicago region. Those accounts haven’t told the whole story, though, and I have a few last photos to shake out of the bag. These fill out some of the experience of doing this kind of regional study.

For instance, other animals have enhanced the delight.

The chalk-fronted corporal is a dragonfly I have encountered only in the northern portion of the region, in this case at the Lulu Lake Nature Preserve in northern Walworth County, Wisconsin.

Walsh’s grasshopper was a new one for me. Not a singing species, but an interesting find at the Poverty Prairie in DuPage County’s Waterfall Glen Forest Preserve.

Turkey vultures assemble at dusk on the Culver, Indiana, water tower. My travels take me back to my home town a few times each season.

Interesting and beautiful scenes are to be found in the relatively undisturbed wild areas which are my main destinations.

An early evening rainbow at Conrad Station in the Indiana Kankakee Sands presaged a thunderstorm-dodging drive home on July 2.

Pinholes between tree leaves cast solar eclipse shadows at Blackwell Forest Preserve. Though the moon covered around 90% of the sun at peak, I detected no change in singing insect activity.

One of the more beautiful scenes was this panne in the Indiana dunes.

I had hoped to find delicate meadow katydids in the pannes. Dusky-faced meadow katydids were a good find there, but that species has a solid hold in other dunes wetlands.

The Pembroke Savanna in the Illinois Kankakee Sands is one of my favorite sites.

I believe these white pines at Warren Dunes State Park in Berrien County, Michigan, are the same ones where Richard Alexander found treetop bush katydids in 1971. He described the trees as small, but all are tall now. They still foster pine tree crickets, but I did not find any bush katydids.

I ended up with 115 county records for the season, totaling all newly found singing insect species over all the counties.

So far, I have found sprinkled grasshoppers only in oak savannas on sand soils.

Dusky-faced meadow katydids at the Indiana Kankakee Sands were a Newton County record.

This curve-tailed bush katydid at the Jasper-Pulaski Fish and Wildlife Area in Indiana provided a Jasper County record for my study.

I found a healthy population of long-tailed meadow katydids, including this brown-legged male, at Ferson Creek Fen in Kane County.

The Ferson Creek population also had green-legged variants, including this female.

Lisa Rainsong, Wendy Partridge and I drove south to Loda Prairie to check out the bush cicadas there. I concluded this year that the species does not occur in the Chicago region.

This Texas bush katydid was singing in early October at Springbrook Prairie Forest Preserve, DuPage County. I had an observation of this species on October 17, my latest ever in the region.

Most of the long winter remains, and as I compile data, write reports, and visit museums, I will be looking forward to another collection of rich experiences as I resume my field study in 2018.

 

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.

DuPage Robust Coneheads

by Carl Strang

Last year, while conducting an evening survey drive to map fall field cricket distributions in my home county of DuPage in Illinois, I was passing through Springbrook Prairie Forest Preserve when I thought I heard a couple robust coneheads singing.

Male robust conehead in singing posture, Newton County, Indiana

Male robust conehead in singing posture, Newton County, Indiana

This was surprising, and I wasn’t able to follow up in 2012, but it was on this year’s research checklist, and on Monday evening I heard them again in the same location. I found a place to park, and to make a long story short was able to confirm my suspicion (a later sonograph analysis of the recording I made will determine whether this was a robust conehead or, less likely given the loudness of the song, a false robust conehead).

This discovery was surprising because in general I have been finding them, as researchers in past decades also have noted, mainly in areas with sandy soils.  No such soils exist outside children’s playgrounds in DuPage. On the other hand, no lesser a light than Richard Alexander listed DuPage County as a place where he had found the species a few decades ago. This is not a simple matter of latitude, as robust coneheads are abundant in sandy Lake County, Illinois, to the north. This species joins the tinkling ground cricket and spring trig as species that I have found in the county, but only in extremely small numbers in one or two places. DuPage County, out of all the 22 counties in my regional survey, is the one I have surveyed most thoroughly, and for nearly 8 full seasons. These few locally rare species are indicators that there probably will be holes in my distributional records for all counties, and so these will need to be judged accordingly. I will need to continue searching for new sites through the seasons and years, as long as I am able to do so.

Slow Day

by Carl Strang

Saturday was cool with intervals of rain, so there wasn’t much to be done with singing insects. I checked out Springbrook Prairie in the morning, and Tri-County (JPP) State Park in the evening, hoping for spring trigs, but no luck there.

Walking the trails at Tri-County, I found a dark grasshopper.

It was on the trail, had the colors of a green-striped grasshopper, but was large, perhaps an inch and a quarter long.

It was on the trail, had the colors of a green-striped grasshopper, but was large, perhaps an inch and a quarter long.

It was unable to perform a sustained flight. Somehow I missed the fact that it had lost one or both hind legs. I am not fully confident of my grasshopper anatomy, but this individual appears to be a female, which would account for the size. It is, then, an unusual brown female of the species (typically, females are green, males brown). And that was it for Saturday’s research production.

Barn Swallow Species Dossier

by Carl Strang

Swallow, Barn

A barn swallow at its nest

A barn swallow at its nest

These swallows build supported mud nests in the shelter of barn structures or bridges. They catch insects during continuous, usually fairly low flight. I have seen similar nests in Pennsylvania, Indiana and Illinois. The vocalizations are chattery relative to those of tree swallows.

26MY86. I compared barn and tree swallows foraging over a meadow near McKee Marsh. Both species flew low over the grass tops. Barn swallows had a somewhat smoother, more fluid flight path.

Summer 1986. Barn swallows nested on buildings of the Basin lodge complex at Big Bend National Park. They were very tame and approachable. One started a beautiful, complex song just before 5am, 1.5 hours before sunrise, and some were out flying in the dark that early. That song seemed to develop at first slow and more measured with simpler phrases and longer intervals between them. Gradually it accelerated and increased in complexity.

Migrating barn swallows take a break

Migrating barn swallows take a break

Mid-SE86. Barn swallows migrated in small groups (1-4), sometimes in the company of other swallows or swifts. Mostly they were 100 or more feet above the ground.

20JL99. More than a dozen barn swallows have appeared over the Willowbrook Nature Trail area, flying low; cloudy with occasional showers.

24AP00. First barn swallow of the season was a single individual flying over Willowbrook.

23AU09. They seem to be migrating, but there still are nestlings at Springbrook Prairie.

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.

Meadow Tree Crickets

by Carl Strang

Some tree crickets live in trees, others live among the trees in the forest understory, but there are a few species that inhabit meadow and prairie areas. Last week I looked at some of these when I did some sweep sampling in two locations. The first was Springbrook Prairie Forest Preserve.

This low area dominated by big bluestem grass was part of the habitat I surveyed.

I went there in hope of finding more of the cicadas, tentatively identified as swamp cicadas, that I heard there last year. At the time the song seemed definitive, but I since have learned that Linne’s cicadas sometimes have songs that are similar, and so I was hoping to find one to photograph. All was quiet, however. That’s not necessarily a bad sign. If this is indeed a new population (DuPage is north of the published range for swamp cicadas), they might not be emerging every year. In any case, while I was waiting for singing cicadas I did some sweep sampling, and turned up several tree crickets.

Here is one of the individuals I caught in a goldenrod-dominated area. It has a dark stripe down the top of the head and pronotum, as well as dark antennae. Despite the otherwise pale color, these features point to the black-horned/Forbes’s pair of tree cricket sibling species.

Proper identification of these tree crickets requires an examination of spotting on the basal two antenna segments.

Here the spots on the first, basal segment are very large and smudged. Those on the second segment likewise, to the point where the entire segment looks black at first glance. Also note the dark area on the underside of this tree cricket’s abdomen. All these features point to black-horned/Forbes’s.

The next cricket, from the big bluestem area, is much paler, and shows a different antennal spot pattern.

Here the spots all are smaller, and the outer ones on the basal segments are round and have smeared edges. This is a four-spotted tree cricket.

Another Springbrook tree cricket was more ambiguous.

This individual happily nibbling my finger shows spotting that falls within the range of overlap for four-spotted and black-horned/Forbes’s tree crickets. The most definitive spot is the outer one on the basal segment. It appears just large enough to rule out four-spotted.

The next day I did some sweep sampling at Mayslake Forest Preserve.

The sample included several pale tree crickets like this.

The cricket in that last photo had the following spot pattern.

This is a clear indicator of four-spotted tree cricket, the outer spots on both segments small, round, and faded looking.

A final example showed even fainter spots.

Again I identified this one as a four-spotted tree cricket.

There is a fourth meadow species that I have been watching for but so far have not found. The prairie tree cricket is generally pale, like the four-spotted. Its antenna spots are heavy and close together, but without the blurred smudging of the black-horned/Forbes’s species pair.

DuPage Swamp Cicadas

by Carl Strang

Not long ago I mentioned that I have begun listening for songs of the swamp cicada, Tibicen chloromera, in DuPage County. Since then I have heard some songs that seemed close, but none that were completely convincing. That changed on Wednesday morning, when I heard unmistakable songs from several individuals of this species at Springbrook Prairie Forest Preserve, in southwest Naperville. The habitat and song perches were just as the literature would lead one to expect: the cicadas were singing from small bur oak trees in a mesic prairie adjacent to a stream. Specifically they were in the Springbrook “remeander” project area.

The photo, taken in 2007, shows the stream shortly after it was converted from a ruler-straight ditch to a stable channel shape with bends, or meanders. Alongside were planted the small bur oaks and a variety of prairie forbs. There is no historical evidence for a natural meandering stream at the site, so it is likely that a sheet-flowing swale, rather than a defined, meandering streambed, preceded the straight ditch. The meanders have the effect of reducing the stream’s steepness, slowing it down so erosion is minimized. Aided by the resulting diverse array of pools and riffles, the stream can support a greater diversity of life. The project rightly has earned several awards for the Forest Preserve District of DuPage County. Two Naperville high schools send Advanced Placement Environmental Science classes to collect data from the project each year, and I was there on Wednesday in connection with that educational dimension.

The cicadas did not sing for a very long time. I wonder if their being closer to the edge of the species’ range explains the more limited habitat variety, song perch choice and singing period I seem to be finding in DuPage County, compared to chloromera I have been observing in the more southern Culver, Indiana, area I referenced in the earlier post. Such thoughts will inform my continued search for swamp cicadas in DuPage.

Bush Katydids

by Carl Strang

One of the goals in my singing insects research this year was to get a better handle on two of the bush katydids, the broad-winged bush katydid and the Texas bush katydid (in the “W” years I was repeatedly amused by the fact that there is such a thing as a Texas bush katydid: nature nerd humor).

Texas bush katydid 3b

The above photo is of Scudderia texensis. I have found Texas bush katydids much easier to approach and photograph than broad-winged bush katydids (S. pistillata). During my recent trip to the U.P. I found one of the latter that held still long enough.

Broad-winged bush katydid 3b

While the two look very similar to one another, the broad-winged is a distinctly smaller insect. Also, the wing proportions are different, as you can see roughly by comparing wing lengths to hind leg femur lengths in the above photos. This broad-winged is missing the end of its left forewing, but the longer hind wings are intact.

With such great camouflage, these katydids are not easy to find, and in survey work I want to identify them by song. Each of these species has two different songs, one very brief and one more extended. The more commonly produced songs, especially in daylight, are the short songs. To my ear the short songs of these two katydids are so similar that I remain uncertain about distinguishing them. These songs are very quick, lasting one-third to one-half second, and are series of 3-5 pulses. I think that the pulses of the Texas bush katydid may prove to be more distinct, like separate syllables: “dig-a-dig.” The pulses of the broad-winged may be more run together and with less of a raspy, more of a lisping quality.

In trying to sort this out I have been seeking the conditions in which these two insects sing their longer songs, which are very distinctive but less often produced. The Texas bush katydid sings its long song mainly at dusk. The song is like an extended version of the short song, lasting 3-4 seconds, dig-a-dig-a-dig-a-dig-a-dig, with the final syllable louder.

Texas bush katydid 8b

The broad-winged bush katydid is renowned for its long song, called its counting song. The elements of the song are lispy buzzes, each lasting a second or so. The remarkable thing is that these buzzes are grouped, and the buzzes increase in number from group to group as the song progresses. Within a group, buzzes follow one another immediately, with a few seconds between groups. A sequence might begin with a single buzz, followed by a group of two, then a group of four, then a group of 5 or 6. Commonly there are four groups in a song, but sometimes there are more. Then the katydid waits for a longer pause before starting a new sequence. Somewhat frustrating is my experience that the season in which broad-winged bush katydids sing their longer songs apparently is very brief in DuPage County. This year I went repeatedly to Springbrook Prairie Forest Preserve, after I first heard bush katydid short songs on July 20. At dusk on the evening of July 26 I heard only broad-wingeds singing counting songs. In 2008 I heard them at Blackwell on July 21. This year I heard them for the last time on August 2. On my next visit, August 7, there were none, and none on several visits thereafter. Though many nighttime singing insects extend their singing into the daytime later in the season, this does not seem true for the long songs of these two bush katydids in DuPage County. However, near the tip of the U.P. in late September, broad-wingeds were singing counting sequences in the late afternoon. It may or may not be significant that Texas bush katydids do not occur there.

This year I heard Texas bush katydid long songs only on August 6 and September 2. Last year I heard them on August 27 and September 2, and in 2007 on July 15 and October 4. So far, then, all years taken together, the season for long songs in DuPage County has been July 21 to August 2 for broad-wingeds, July 15 to October 4 for Texas bush katydids. The broad-winged’s season is longer, or at least later, farther north. And that’s where it stands. Lately all the short songs I am hearing have the distinct-syllable quality I associate with Texas bush katydids. Next year I will continue to sort out this puzzle.

Incidentally, there are other species of bush katydids in our area. One I’ll mention here is the curve-tailed bush katydid, S. curvicauda. It is more a forest edge species than the meadow-loving Texas and broad-winged bush katydids. Its songs are composed of loud rasping “zik!” syllables. Commonly it produces these in sets of three, but it also has simple counting sequences. Aside from the different sound quality, these differ from those of the broad-winged by having fewer groups (only 2-3 groups per sequence) and simpler sequences (2-3, 2-3-4, 3-3-4, etc.).

As always, you can find recordings of these various songs on line. I recommend the Singing Insects website  and the Songs of Insects website.

Two-spotted Tree Cricket

by Carl Strang

One of the goals in my singing insects study this year is to sort out the songs of three arboreal tree crickets. In the field I have found that their songs are not as distinct from one another as reference recordings and descriptions seemed to suggest. Two of the three species I have seen, and so confirmed their presence in DuPage County. Today I begin with what I suspect may be the only one singing as early in the season as late July and early August: the two-spotted tree cricket.

Two-spotted tree cricket 1b

This photo shows a female, with the two large spots on her back that give the species its name (males lack them, and are pale). She sits on the arm of one of the 2006 Roger Raccoon Club  kids, who brought her to me for identification. Until two weeks ago, she was the only one I had seen. Certainly the references were correct in saying these are not easy to find. They live in trees, often well above the ground. The male’s song, which you can find here  or here, is a strained, often dissonant sounding trill that is interrupted fairly frequently by brief pauses that often are filled with stuttering sounds. Unfortunately, the same description applies more or less to the songs of Davis’s tree cricket and the narrow-winged tree cricket, though the tone of the last seems more melodic to my ear.

Two-spotteds begin to sing at dusk. On August 6 I was at Timber Ridge Forest Preserve, strolling the Great Western Trail with ears open for insect songs, when scattered tree crickets in this target group began to sing. All had identical songs, but one in particular seemed to be closer to the ground and just off the trail. After a short time I found him.

2-spotted singing b

He was on the underside of a big grape leaf. Here he is close up.

2-spotted singing cropped b

He was using a trick for which some of the tree crickets are known. He had chewed a circular hole in the leaf, and was using it to amplify and possibly direct his song (tree crickets sing by elevating their wings and vibrating them against one another).

2-spotted wings down b

I made a recording, then prepared to collect him for identification. But when I put my flashlight on him again I found this was unnecessary.

2-spotted pair 2b

A female had arrived on the scene, and there was no mistaking her identity. The male kept his wings elevated, and continued to vibrate them occasionally in song. She was palpating her way slowly up his back in search, I believe, of secretions that some of the tree cricket males provide as nuptial food gifts in a prelude to mating.

2-spotted pair 1b

The next evening at dusk I was at Springbrook Prairie Forest Preserve. I heard the same song coming from near the top of a 15-foot-tall bur oak beside the trail. Looking up toward the point from which the sound seemed to be coming, I noticed that one of the leaves had a circular hole in the middle. When I illuminated it with my flashlight, sure enough, there was another male two-spotted tree cricket. So, at least with plants having relatively large leaves, I now know to look for distinctive circular holes that may help me to find these elusive insects.

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