Site Map Project

by Carl Strang

Up to this point I have reported singing insect distributions in the Chicago region at the county level. For instance, here is an Allard’s ground cricket (Allonemobius allardi) and its species distribution by county.

Male Allard’s ground cricket

The black dots simply show that I have found Allard’s in every county of my study region.

But I have a lot more data than that which I wanted to share. Also, I thought that maybe a finer grained mapping approach might reveal new questions for me to investigate. I had a spreadsheet with a species list for every site I have visited. So, I recently created a series of maps showing the sites where I have found each species over the years. Here is the resulting map for Allard’s ground cricket:

Filled circles indicate sites where I have observed Allard’s ground crickets. Open circles are places I have visited where I haven’t (yet) noted that species.

As you can see, this is a widespread and frequently encountered cricket. The map reveals significant areas with no sites. Some of these are vast empty (from a biodiversity standpoint) agricultural regions, but still I should give them more attention.

One more example for today. The long-spurred meadow katydid (Orchelimum silvaticum) reaches its northern range limit in the Chicago region.

Long-spurred meadow katydid, male

The county-level map showed this, but the site level map makes it even clearer.

The northernmost sites where I have found long-spurred meadow katydids line up impressively at the same latitude.

These two examples simply emphasize conclusions I had drawn previously. Some intriguing questions were raised in other cases, as I will share in upcoming posts.

Morgan Monroe-Yellowwood Ecoblitz

by Carl Strang

The Indiana Forest Alliance is sponsoring a multi-year species survey of the back country portion of the conjoined Morgan Monroe and Yellowwood State Forests in Monroe and Brown Counties of southern Indiana. They are holding bioblitz weekends at various seasons so as to get a more complete picture than a single bioblitz would produce. Jeff and Mary Stant are providing the principal organizational and logistical support. I paid my first visit on September 12 to begin inventorying the singing insect species.

While waiting my turn to go into the survey area, I checked out the base camp in an old field with scattered young trees adjacent to the riparian edge of a wooded stream. The species mix was much like I would expect to find in a dry area in northern Indiana or Illinois.

Woodland meadow katydids were very common in woodland edges, much more abundant than I have found them farther north.

Woodland meadow katydids were very common in woodland edges, much more abundant than I have found them farther north.

The old field held scattered common meadow katydids.

The old field held scattered common meadow katydids.

Handsome trigs also were common in the riparian edge.

Handsome trigs also were common in the riparian edge.

Allard’s ground crickets were one of several species at the camp.

Allard’s ground crickets were one of several species at the camp.

The forested survey area was, as expected, less diverse, though the cool afternoon temperature probably inhibited some species. The slopes held scattered confused ground crickets, and bottomland herbaceous thickets were full of Say’s trigs, along with good numbers of Carolina ground crickets and more scattered jumping bush crickets and narrow-winged tree crickets.

At one point we flushed out a medium-sized cricket which permitted a quick photo but evaded capture. It was one of the camel crickets, probably in genus Ceuthophilus.

At one point we flushed out a medium-sized cricket which permitted a quick photo but evaded capture. It was one of the camel crickets, probably in genus Ceuthophilus.

We went up to a ridge top in the evening. It was very cold, and few species were managing to sing. There were scattered tinkling ground crickets, Carolina ground crickets, jumping bush crickets, and a few feebly ticking long-spurred meadow katydids. A background hum came from the forest canopy, and occasional individuals could be distinguished to support an identification of Davis’s tree crickets, by far the most abundant singers on that cold night.

I look forward to returning for more ecoblitz weekends next year.

 

Sound Ideas: Common Ground Crickets

by Carl Strang

There are 3 species of ground crickets that occur throughout the Chicago region (I still lack 2 county records for one of these, but expect to make up that deficit on a future Wisconsin trip). The ground crickets are the LBJ’s of singing insects (birding jargon: “little brown jobs” refers to sparrows, wrens and the like which are quick to vanish before they can be identified). Most ground crickets look identical at first glance, are tiny, and usually are brown. I’ll begin with the striped ground cricket.

The stripes are clear on this female striped ground cricket’s head.

The stripes are clear on this female striped ground cricket’s head.

This is the weediest of the ground crickets, first to show up in disturbed sites, and abundant in lawns. Its song consists of separate brief rough buzzes, continuously produced at 2 to 3 per second. It is low enough in pitch to hear easily, with most of the buzz’s sound range below 7 kHz. Here is a recording (complete with background bird songs and the usual traffic rumble):

The second species also occurs in open areas, but mainly where the grass is taller and vegetation better established.

Allard’s ground cricket is a close relative of the striped. The head stripes are absent, faint, or incomplete, however.

Allard’s ground cricket is a close relative of the striped. The head stripes are absent, faint, or incomplete, however.

The song consists of incessant, separate quick very high-pitched notes (6 kHz) that sound like 4-6 per second but sonographs show twice that rate. There are fairly frequent, very brief pauses (again, birds and this time a train in the background):

Now I will toss in a fourth species. The tinkling ground cricket is less widely distributed than the others (so far I have found it in half of the region’s counties), but include it here to provide a comparison to the Allard’s song. Here is a recording:

The song consists of high pitched (7 kHz) individual notes, like those of Allard’s ground cricket but distinctly slower at a given temperature (1/3 to ½ as rapidly produced). It often is rendered “tink-tink-tink…” The song is uninterrupted, lacking the frequent breaks characteristic of Allard’s ground cricket (this is especially helpful late in the season, when Allard’s often slows down). The tinkling ground cricket lives in open woodlands and woods edges, and is especially abundant on sandy soils. It looks different, too.

Tinkling ground crickets have reddish tones that distinguish them from our other ground crickets.

Tinkling ground crickets have reddish tones that distinguish them from our other ground crickets.

The final, common species is the Carolina ground cricket.

The Carolina ground cricket has faint head stripes. The female is distinguished by an unusually short ovipositor.

The Carolina ground cricket has faint head stripes. The female is distinguished by an unusually short ovipositor.

Its song is a continuous, irregularly pulsed drone, purr or trill with periods when additional pitches are added to the song, making it more dissonant. Though the sound pulses are broad enough in pitch range to qualify as a drone, it is not far from a trill, and low enough in pitch to be heard by most, at 6 kHz. Here is a recording:

As the passing geese perhaps imply, Carolina ground crickets prefer moist habitats, from wetland edges to bottomland forests. In my residential neighborhood they are fairly common, but stick to the cooler, moister foundation shrub plantings against the houses.

We’ll have to wait a while to hear these crickets again. They winter in the egg form, and need until the very end of June or, more often, July to develop to the point where they begin singing.

Sound Ideas: Gray Ground Cricket

by Carl Strang

In the vegetation that grows just behind the beaches around the western Great Lakes you may hear a very rapid, high-pitched trilling sound, as in this recording I made at Whitefish Point (on the north side of the tip of Michigan’s Upper Peninsula) on September 16, 2009:

The area where the previous recording was made.

The area where the previous recording was made.

This interrupted trill is identical to the reference recording for the gray ground cricket on the Singing Insects of North America website. Indeed, this species is expected in open, sandy soil habitats. The only other ground cricket song I have heard that is close to this is that of the sphagnum ground cricket, which is restricted to sphagnum bogs and could not survive on sand. Allard’s ground cricket, when it occurs with the gray ground cricket, has a distinctly slower song.

The challenge for me with this species has been two-fold. First, I have never seen one. Second, I am pretty sure they occur inland as well. Here is a recording from Braidwood Dunes, a Will County Forest Preserve, September 7, 2011:

At the time I noted that there were pauses, but enough crickets were singing simultaneously that these are difficult to pick out in the recording. I have heard, and sometimes recorded, this same song in other inland locations in Kendall, Marshall and Fulton Counties. Sometimes the pauses are infrequent or nearly absent, but the songs all have a peak frequency of 8-8.5 kHz, and share similar patterns of amplitude irregularity in their sonographs. I am not aware of any other cricket that could occur in dry soils with a song like this. Furthermore, there are some mentions of inland gray ground crickets in the literature, and some authors refer to the trill as continuous. So, mainly by process of elimination I have decided to refer to all these crickets as gray ground crickets for now, but with a higher priority of catching one, particularly at one of the inland sites, for confirmation.

Dispersal Ability

by Carl Strang

In order for us to understand insects well enough to know which ones need the most attention in conservation, there are some pieces of information we need: how abundant they are, how broad or narrow their habitat needs, their reproductive potential, and their dispersal ability. The first two items are readily obtained in the course of a regional survey such as I am conducting for singing insects in northeast Illinois and counties in neighboring states. Reproductive potential has been studied to some extent and can be found in the literature for some species. Dispersal ability is a critical point that is not well studied as far as I can tell, and so it is good to take advantage of observations that reveal which species spread easily, and which ones do not.

Over the past two weeks I spent much time in the St. Joseph Hospital in Mishawaka, Indiana, where the medical professionals saved my mother’s life.

The hospital was built 3-4 years ago, and is surrounded by extensive areas planted mainly in native prairie plants.

The hospital was built 3-4 years ago, and is surrounded by extensive areas planted mainly in native prairie plants.

Occasionally I took walks along the paths, or made observations while arriving or departing. The species present in the plantings can be regarded as ones with high dispersal ability. These included field crickets (I cannot be sure which, as this was the cusp between the spring and fall field cricket seasons), striped and Allard’s ground crickets, Carolina grasshoppers, Roesel’s katydids, and a sword-bearing conehead. All of these are regionally abundant, and fairly broad in their habitat (dry to mesic mixes of grasses and forbs). Three have good flying ability (in the case of Roesel’s, there are long-winged individuals as well as medium and short-winged ones). Field crickets and the ground crickets can take advantage of their regional abundance and tendency to hop and walk over land. One limitation here is that I was only able to make observations over a brief portion of the season.

If I had to point to the weediest singing insect in our region, I’d have to say it’s the striped ground cricket, which is the quickest to appear in a new site.

First and Last Song Dates

by Carl Strang

I now have 7 years’ data in which I have noted the first and last dates on which I heard each singing insect species. This year was characterized by a mild winter followed by a warm spring and then a summer of drought. The mild winter and spring apparently were responsible for this year’s early phenology. First song dates were the earliest I have recorded in DuPage County for 17 of the 21 species for which I have 7 years of records. The chi-squared value of 77.33 (with an expected value of 3 species per cell for each rank of earliest to latest) is, of course, statistically significant.

The greater angle-wing started earlier and finished earlier this year than in any of the previous 6 years.

The greater angle-wing started earlier and finished earlier this year than in any of the previous 6 years.

As for last song dates, singing insects generally finished early this year. Of the 20 species for which I have 7 years’ data, 15 had their earliest or second-earliest ending dates, and the chi-squared value was a statistically significant 22.68. This was not a particularly cold or dry late summer and autumn, so the implication is that singing insects have a fixed rate of attrition or duration of song season, so that an early start results in an early finish. The 12 species for which I have the best, most reliable records do have differences in observed song season lengths (ranges for the 7 years, and ranked lowest to highest: 18-42 days for Roesel’s katydid, 16-52 days for gladiator meadow katydid, 52-96 days for the greater angle-wing, 58-96 days for snowy tree cricket, 67-91 days for the scissor-grinder cicada, 64-94 days for the greenstriped grasshopper, 62-109 days for Linne’s cicada, 72-105 days for the dog day cicada, 81-107 days for the common true katydid, 107-139 days for Allard’s ground cricket, 111-141 days for striped ground cricket, and 113-143 days for Carolina ground cricket).

The number of clear, cold nights seemed high enough in November that they might partly explain the early conclusion of common ground cricket songs this year, especially given the recent study by MacMillan et al. (2012) indicating that there is a metabolic cost to recovering from cold-temperature paralysis. However, I found no significant relationship between last song dates and the number of November days with low temperatures below 33F over 2006-2012 for any of the three species (Spearman’s r values 0.51 for Allard’s ground cricket, -0.39 for striped ground cricket, and 0.33 for Carolina ground cricket). It is interesting, though, that I have seen a few red-legged grasshoppers active a couple weeks after the last ground cricket.

An early December red-legged grasshopper

An early December red-legged grasshopper

This bigger insect may have larger fat reserves to draw upon and so extend its season.

Common Ground Crickets

by Carl Strang

Ground crickets are the most difficult group of singing insects to photograph. I have spent hours seeking the various species, and still do not have photos of both genders of several species for the guide I have been developing for the Chicago area. Females are easier to find. For one thing, they wander more.

Females come out into the open sometimes as they travel in search of singing males or oviposition sites.

The acrobatic individual in the above photo is a Carolina ground cricket. I also held one in a jar briefly, but when I released her she escaped before I could get a sharp photo.

Of our common three ground cricket species, the Carolina female is distinguished by her short ovipositor, shorter than the femur length.

Of course, to some degree if you have seen one ground cricket you have seen them all. Here is a female striped ground cricket.

The longer ovipositor, subtle differences in body proportions, and especially the stripes on the head separate this one from the Carolina ground cricket.

The third common species is Allard’s ground cricket. Here is an earlier photo of a female.

There is head striping here as well, but sometimes it is obscure.

Fortunately for monitoring purposes, the male songs of these three species are easily distinguished. And after all, since they are going mainly by the songs themselves, there is little if any selective pressure for them to look different. Still, I want those photos. I still need one of a male Carolina, and that is my final field research goal for this season.

Recent Mayslake Singers

by Carl Strang

There have been a number of singing insect photo opportunities of late at Mayslake Forest Preserve. The best, just yesterday morning, was the first long-spurred meadow katydid I have found on the preserve. I could hear its quiet song, but it took a while to find it, tucked into a clump of weedy plants a few feet out from the edge of a woodland.

This angle provided just what was needed to confirm the identification, the long spurs on the cerci showing clearly.

Earlier in the week I found a round-tipped conehead singing close to the ground in a tuft of grass.

This is the most abundant coneheaded katydid in DuPage County, the latest of them to mature and the only one that sings in the afternoon as well as at night.

Last weekend, one of the families on my night hike found a narrow-winged tree cricket on the sidewalk after we finished.

The flash washed out its image a little, but the brown cap and narrow wings show clearly in this photo.

Still earlier an Allard’s ground cricket, the most abundant of Mayslake’s ground crickets, paused while crossing a trail.

Unless the autumn is severe, Allard’s will sing well into November.

Numbers of singing insects are dropping, but there still are plenty to hear this season.

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.

Chain O’Lakes

by Carl Strang

Last week I spent a day and night at Chain O’Lakes State Park, near the Wisconsin border in Illinois. There are extensive wetlands in that park as well as dry upland areas. Though my singing insect search for the most part turned up common, expected species, I have hope for better results in a future wetter year. In the extensive upland restored prairie areas Allard’s ground crickets were the main daytime singers. In a lower, damper, goldenrod-dominated patch were some black-horned tree crickets (or, possibly, their sibling species the Forbes’s tree cricket).

The heavy but well separated basal spots on the antennae plus the dark antennal color identify this as a black-horned.

In a higher-quality prairie patch not far from some trees I found a bush katydid.

The species cannot be determined from this angle.

A quick capture made for an easy identification.

The brown, curved ovipositor distinguishes the female fork-tailed bush katydid.

Later, after dark, I heard a number of sword-bearing coneheads in the prairie areas.

This species, with its distinctive sewing-machine song, is common in meadows and prairies of the region.

Wetlands are abundant at this park, and some appear to be relatively high in quality.

Pike Marsh

The singing insects were of common species for the most part.

The slender meadow katydid is abundant in wet places.

The most conservative species I found at Chain O’Lakes was a female long-tailed meadow katydid.

This was the first green-legged female of this species I have seen. Usually they are all brown.

I will return to that park in a wetter year.

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