Ecoblitz Continued

by Carl Strang

The Indiana Forest Alliance, a non-profit conservation organization, has been sponsoring a species survey in portions of two state forests in southern Indiana. As it consists of repeated weekend sessions over a period of years, they are calling it an “ecoblitz” rather than a bioblitz, which is a one-time event limited to a 24- or 48-hour time span. I went down for a weekend last fall, and returned in early August to complete the singing insects portion of the survey.

The area is forested, except for some small areas of tall, dense herbaceous growth in stream bottoms. The singing insect fauna consequently is mainly of forest species.

Confused ground crickets were common on the forest floor.

Confused ground crickets were common on the forest floor.

Say’s trigs by the hundreds sang in the open herbaceous areas.

Say’s trigs by the hundreds sang in the open herbaceous areas.

Widely scattered small groups of rattler round-winged katydids could be heard at night.

Widely scattered small groups of rattler round-winged katydids could be heard at night.

This nymph is recognizable as a male fork-tailed bush katydid by the distinctive appendages at the tip of his abdomen.

This nymph is recognizable as a male fork-tailed bush katydid by the distinctive appendages at the tip of his abdomen.

Some of the other species that sang for us were swamp cicadas, Nebraska coneheads, lesser angle-wing katydids, jumping bush crickets and common true katydids.

I also helped with photography at a night-time moth survey at illuminated sheets.

This small-eyed sphinx was one of the two hummingbird moths we attracted.

This small-eyed sphinx was one of the two hummingbird moths we attracted.

A blinded sphinx also dropped in.

A blinded sphinx also dropped in.

A grape leaffolder

A grape leaffolder

This lesser grapevine looper appears to be sending out pheromone.

This lesser grapevine looper appears to be sending out pheromone.

A Cope’s gray treefrog hopped in, possibly sensing the smorgasbord we had created.

A Cope’s gray treefrog hopped in, possibly sensing the smorgasbord we had created.

 

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: 3 Ground Crickets

by Carl Strang

Today I share recordings of 3 ground crickets. The first of these, the melodious ground cricket, is not very well studied, and recordings of its song are not commonly available.

Melodious ground cricket

Melodious ground cricket

The song is a fairly loud, steady trill with a pleasant tone:

That song is most like that of Say’s trig, which can occur in close proximity as both are wetland species. When such is the case, the distinction is clear. Here is a recording of Say’s trig for comparison:

The recordings are a little misleading in that both species can be equally loud. Next up is the sphagnum ground cricket.

Sphagnum ground cricket. This species does not occur away from sphagnum moss.

Sphagnum ground cricket. This species does not occur away from sphagnum moss.

The song is higher pitched and more rapid than that of Say’s trig, which again often co-occurs.

The final species has an interrupted trill, unlike the continuous singing of the previous crickets. The confused ground cricket usually is found in drier portions of woodlands than the more swamp-dwelling melodious ground cricket.

Confused ground cricket

Confused ground cricket

The song is about one second on, one second off. If there are few other sounds, you may hear some stuttering during the “off” intervals:

 

Sound Ideas: Variegated and Cuban Ground Crickets

by Carl Strang

One of the highlights of the field season just past was finding variegated ground crickets, a long sought species, right under my nose, as described earlier.

Variegated ground cricket

Variegated ground cricket

Here is a recording I made in 2011 in the lawn at Mayslake Forest Preserve. I have trimmed out all but the critical end portion, which includes the abrupt end of one trill and the crescendo beginning of another:

I had made the incorrect assumption that these crickets, living in cracks and holes in the lawn, were Say’s trigs. Here is a recording of one of the trigs from nearby Fullersburg Woods Forest Preserve. The ending likewise is abrupt, but the next trill has a “chuwee” beginning.

In both cases the trills are extended, longer in the trig as a rule. A third species worth comparing here is the Cuban ground cricket. I have not encountered this species in the Chicago region, yet, but I need to be alert for it. Previously known only as a southern species, Lisa Rainsong has found it to be common in the Cleveland area. Ecologically it seems to resemble the variegated ground cricket in liking wet areas near lakes, rivers, and marshes, but is active on the surface rather than remaining out of sight in gravel or in soil crevices. Here is a partial recording of a Cuban ground cricket living in a terrarium in Lisa’s home:

The repeated brief scratches or chirps are from a striped ground cricket in another terrarium. The Cuban ground cricket, a member of the same genus as the variegated, likewise has a crescendo beginning, an extended high-pitched trill, and an abrupt ending. The pitch is just a little lower than that of the variegated, but otherwise they are much the same.

A final note on this topic is that my analysis allowed me to identify a recording from Illinois Beach State Park as belonging to a variegated ground cricket.

The singer was located beneath this vegetation, a few steps from the Dead River. I could not find it, and now realize that it must have been beneath the surface.

The singer was located beneath this vegetation, a few steps from the Dead River. I could not find it, and now realize that it must have been beneath the surface.

Here is an excerpt from the recording (you may need to turn up the volume):

All of this has me primed to document variegated ground crickets elsewhere in the coming season, and to be alert for Cuban ground crickets.

 

Sometimes It Gets Messy

by Carl Strang

I haven’t been posting here lately, as I have been busy writing summaries and reports on the past season of my singing insects study. As 2014 was a good, productive year, this has been a time consuming process. The discovery of variegated ground crickets in October brought a new complication, as their song superficially resembles those of several other crickets, including Say’s trig and a few other ground crickets. I decided to review all of my relevant recordings and re-analyze them to discover distinguishing features. Two quantities that researchers have discovered to be significant in singing insects are dominant frequency (pitch or highness of the tone) and pulse rate (the speed at which wings open and close to produce the song). These are determined by sonographic analysis of the recordings in the computer. The plot of all the recordings looks like this:

Hence “messy” in this post’s title.

Hence “messy” in this post’s title.

The colors represent my decision as to species (usually I did not see the singer): red for Say’s trig, green for variegated ground cricket, blue for gray ground cricket, black for sphagnum ground cricket, and yellow for Cuban ground cricket. The shapes represent one of three ways in which these crickets begin their songs: square for an abrupt start (or for unknowns, cases in which the recording did not include the start of a trill), triangle for a crescendo from low volume to the extended peak of loudness, and circle for a start that often is rendered “chuwee.” The last has an abrupt beginning, but immediately has a momentary drop in pitch or volume that as quickly is followed by the continuous, full volume trill. All these crickets end their trills abruptly. Empty centered shapes are for recordings that were noisy or in which more than one individual was singing, potentially leading to a false reading. The numbers are the temperatures in degrees Fahrenheit, when known.

Ideally, there would be well defined clusters of points separating the represented species. This did not happen, and I can identify a few reasons. In some cases, the recording’s quality was compromised (the hollow-centered shapes). Temperature can affect song qualities, and there is no single established threshold for all species, below which recordings become ambiguous. Also, some features of songs are not in the graph, notably the length of trills, and the length of pauses between them.

The outlier for variegated ground crickets, the green triangle with the lower frequency and pulse rate, was the recording I made indoors. I only kept that cricket for one night, and had it in a cage with only a few leaves on its floor. I have more trust in the values for the Cuban ground cricket, which was well established in a beautifully furnished terrarium at Lisa Rainsong’s home in the Cleveland suburbs, where I stopped briefly on my way to my brother’s for Thanksgiving (thanks again, Lisa!).

Here are my tentative conclusions from this analysis:

First, I need to make a lot more recordings, with care to note habitat, temperature, and whether the singer is on the ground or height above the ground. I need to isolate one singer from all others, with the microphone as close to it as possible. Better habitat conditions are needed to get good response for indoor recordings.

So far, dominant frequency, habitat, and how the trill starts are more helpful than pulse rate in distinguishing these species.

Say’s trig songs are characterized by a chuwee start, a location above the ground, and a lower pitch (usually 7.5kHz or less). Trills may be long or short, but when short usually are in rhythmic bouts.

Variegated ground crickets consistently have crescendo starts, trills usually less than a minute long, and pauses between of at least several seconds. Field recordings had high dominant frequencies (8.6 kHz or above).

One Cuban ground cricket recorded indoors had a pattern like that of the variegated, but a lower dominant frequency (7.6 kHz). From Lisa’s description, these two species occur in very similar habitats, but the Cuban ground cricket is more likely to be found on the surface of the ground. Variegateds occupy soil cracks or other buried locations.

Gray ground crickets have abrupt starts and only brief-moment pauses, with dominant frequencies of 8.0-8.9 kHz. They occur in dry sand soils.

One recording of a sphagnum ground cricket has a high dominant frequency (8.5 kHz), plus a chuwee start. It occurs only in sphagnum bogs, but potential associates include Say’s trig and variegated ground cricket, which can be distinguished, respectively, by their lower dominant frequency and crescendo starts.

That’s enough for now. I plan to share some of these recordings in future posts.

How to Title This?

by Carl Strang

I debated what tack to take with this post. There are plenty of possibilities. I could have titled it “Two Problems Solved at Once.” Another possibility was “Well, THAT’s Embarrassing.” Then there’s the old standby, “Another Lesson Learned.” “One More Gift from This Field Season” would have had a more positive twist. I even considered “Tastes Like Chicken,” but that’s too tangential. Maybe I should just tell the story.

The roots of this tale go back in two directions, previously introduced in this blog. One had the title, ironic now, of “A Small Mystery Solved.” In it I described how I had tracked certain long cricket trills to cracks and earthworm holes in shaded portions of the mansion lawn at Mayslake Forest Preserve. Though I didn’t see the crickets, and the match wasn’t perfect, the songs sounded close enough to those of Say’s trigs for me to conclude that they were the singing species, even though they otherwise, in the literature and in my experience, are known as a species that lives in vegetation up off the ground.

To my credit I held onto some skepticism toward this conclusion, and was planning to set pit traps at some point to try and catch one of these crickets. Then an unexpected opportunity appeared. During my lunchtime walk on Tuesday I noticed that small bunches of dried leaves that had collected along the curb were harboring some of these singers. I began pulling out leaves so as to expose what I expected would prove to be Say’s trigs. The songs certainly sounded like those of that species. Crickets began to jump out, mostly tiny immatures, and then I flushed a larger one. It manically jumped away. It was light brown, like a Say’s trig, but not totally so, and I wasn’t able to get a clear view. I tried again, and ultimately one sat still for a photo.

This was not a trig, but a ground cricket.

This was not a trig, but a ground cricket.

That one escaped, but I finally caught another, unfortunately damaging him. I was going to need to collect one, anyway, as ground crickets are one of the most difficult groups to identify. I went through the keys in the Singing Insects of North America website, and placed this cricket in the genus Neonemobius. I leafed through the species pages, and ultimately found a match, right down to the pale palps and the head that was light brown on top but dark brown or black in front.

Could they be variegated ground crickets?

Could they be variegated ground crickets?

That brings me to the other root of this story. The variegated ground cricket’s mapped range encompasses the Chicago area, but information about the species in the literature is limited and anecdotal. Prior to Tuesday there was only one northern Illinois record. The most common theme is that they occur among the pebbles at the edges of streams. I have made a few trips trying to find them (one chronicled here, plus two journeys to Kankakee River State Park), always without success.

So the joke’s on me. For years I have been working right next to a sizeable population of variegated ground crickets without realizing it. I have searched in several counties for them, only to find them literally in my back yard. But what about that “Tastes Like Chicken” title? This is not the only cricket whose song sounds to my ear like that of Say’s trig. There also is the spring trig, which indeed lives close to the ground. The melodious ground cricket’s song is not too far off, though the two are readily distinguished by an experienced ear. From now on I need to be suspicious whenever I think I am hearing a Say’s trig. A moist lawn is far removed from a pebbly stream bank, so with that kind of ecological range I expect to find variegated ground crickets in many more places. I am making recordings, and sometime in the coming winter I will attempt to find a way to distinguish the variegated ground cricket’s song. I will share the results here.

Sound Ideas: Say’s Trig Variations

by Carl Strang

As I listen for singing insects in the summer, at this point I recognize nearly all that I am hearing. Sometimes I hear something that obviously is new and different, as was the case with the green-winged cicada last summer, and I put in the effort needed for an identification. Sometimes a sound is so rarely heard that I am inclined to pass it off as an anomalous sound from a familiar species, though I store it in memory in case it turns up again. Today’s story is a case in point. On a couple occasions last summer I heard songs with the pattern of a confused ground cricket, brief trills with brief spaces between them, in a fairly regular rhythm. The problem with this was that the singers, which I was unable to see, seemed to be above the ground, and they were in wetland edges rather than upland woods. The sound quality was similar to that of Say’s trig, and I figured that this might be an alternate song of that species.

Say’s trig is a common small cricket.

Say’s trig is a common small cricket.

The typical song of this species has been well described as a “silvery trill.” Here’s a recording:

As I dug through my past recordings, I was surprised to find that the one I had made of a temporary captive in my house had the interrupted pattern:

There was no question of the singer’s identity. I also found a field recording of this pattern, at Fullersburg Woods near Salt Creek:

In this example the rhythm is less regular, and leads in the end to an extended normal trill. I am not finding a reference to this interrupted version of the song in the literature I have. It could be a context-driven alternative, or possibly individual variation. I’m certainly not prepared to suggest a different species, though new species in this genus continue to be sorted out.

Sound Ideas: Trigs

by Carl Strang

The first field recording I made this year was at the Connor Prairie bioblitz near Indianapolis, of a mysterious cricket that sounded just like the familiar Say’s trig but was in a mesic prairie habitat and was singing too early in the season. Here is what it sounded like:

With much effort I caught one, and this clearly was no Say’s trig. I collected him.

The head is entirely dark, unlike Say’s trig (see below).

The head is entirely dark, unlike Say’s trig (see below).

It proved to be a spring trig, in the same genus but a distinct species, and in the process of being described by specialists. Until that happens, its label in the Singing Insects of North America website is Anaxipha species G.Say’s trig has a paler head, with a dark line descending diagonally from each compound eye.

Say’s trig female

Say’s trig female

Say’s trig is abundant throughout the Chicago region, in marshes, wet meadows and bottomland woods. So far I have found the spring trig fairly common in Fulton County, Indiana, at the southeast corner of the region, but it diminishes to rare individuals in northeast Illinois. Its preference is grassy prairies and mesic meadows.

The region’s third trig species is the handsome trig, a cricket that seems to prefer brush or thinly wooded edges close to wetlands.

Handsome trig

Handsome trig

Its song is distinct from the other two. Each pulse of its trill has, at least to my ear, a sharp clicking or percussive quality:

A comparison of sonographs shows this difference.

Spring trig sonograph. The selected area is half a second of the recording.

Spring trig sonograph. The selected area is half a second of the recording.

Handsome trig sonograph. Again, half a second is selected.

Handsome trig sonograph. Again, half a second is selected.

The narrow, sharp attack at the beginning of each pulse distinguishes the handsome trig’s song.

Spring Trig

by Carl Strang

This is the story that made my participation in the Connor Prairie Bioblitz worth the trip. Beginning in 2008, I have heard occasional cricket trills that sounded identical to those of Say’s trigs, but were too early in the season. In 2008 my office was at Fullersburg Woods Forest Preserve, and on June 27 I heard one of those odd early songs. I also noted them on July 8 and 14 that year. In 2009 the first Say’s trig was singing on a more reasonable August 6, and in 2011 on July 31. In 2010 the first was on July 19 at Waterfall Glen, a little marginal perhaps but acceptable. Then last year I heard one near the Fox River in Kane County on June 10. Granted, last year was early phenologically, but this was completely out of line. I speculated that perhaps a rare few Say’s trigs hatched early and successfully overwintered as nymphs.

Then came last weekend’s bioblitz at Connor Prairie. This is too early to expect much singing insect action in the woods, so I headed straight to the large prairie restoration project west of the interpretive center.

View of the restored prairie from the balloon.

View of the restored prairie from the balloon.

The same area at ground level. This prairie first was seeded around 5 years ago.

The same area at ground level. This prairie first was seeded around 5 years ago.

There were plenty of spring field crickets chirping, as expected. But as I approached the taller grasses I also began to hear trills. Lots of them. Furthermore, they sounded just like Say’s trigs. On June 8. I began stalking these singers. Several times I got within 2-3 feet, but was never able to see one of the singing crickets in the dense grasses. When my approach stopped the singing, the cricket was able to outwait me. I was fairly certain they were above the ground, and so probably were not ground crickets. They became quiet in late morning. I heard one singing briefly in the afternoon, but that was it.

In the evening I returned, and as the sun slid to the horizon I was pleased to find that the mystery crickets were singing again. Again I tried stalking, and again was frustrated. Then, when yet another cricket stopped singing when I got within 2 feet, I shuffled my feet through the grass clump where his perch seemed to be, and up he hopped. I caught him in a vial.

He was a brown trig, but his head was entirely dark rather than pale with dark stripes as is characteristic of Say’s trig. I made the necessary decision and collected him.

Here he is, pinned and drying. The uniformly colored head is distinctive.

Here he is, pinned and drying. The uniformly colored head is distinctive.

The color, size and shape otherwise are similar to Say’s trig.

The color, size and shape otherwise are similar to Say’s trig.

I returned the next morning, but was unable to flush another male or sweep-net a female. None of my printed references mentioned anything like this cricket. I was able to connect to the Connor Prairie’s Wi-Fi, and searched the Singing Insects of North America website. Imagine my elation when I found it! This is an unusual instance of a species getting a common name before its scientific name is assigned. It has been designated the spring trig, Anaxipha species G. The SINA spreadsheet lists May and June dates, and gives a range that includes Indiana and Illinois, though apparently my cricket is the first specimen for Indiana. So, now there is another species to listen for in my travels. I will want to get some definition of this species’ season relative to Say’s trig. The reasonable assumption is that, unlike other Anaxipha, the spring trig overwinters as a nymph.

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.

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