November 12, 2009 at 6:55 am (singing insects)
Tags: black-horned tree cricket, Blackwell, broad-winged tree cricket, Forbes's tree cricket, Mayslake, Oecanthus forbesi, Oecanthus latipennis, Oecanthus nigricornis
by Carl Strang
Last week on one of the warmer days I was walking through the south savanna at Mayslake when I heard what sounded like a broad-winged tree cricket singing. I had heard some a few weeks earlier, but hadn’t taken the time to find one to photograph, and I thought that here was one last opportunity this season. Eventually I found it, but the insect was no ideal broad-winged.
I was caught without collecting equipment or sound recording equipment, but I got photos before the cricket hopped away. The light wasn’t right, but there did seem to be some color around the head.
It didn’t look like broad-wingeds I’ve seen elsewhere, like the first one at Blackwell a few years ago.
In fact, it looked more like a black-horned or Forbes’s tree cricket, like this one also at Blackwell.
The wing width to length ratio falls between the two, but a little closer to that of the broad-wing. I’m leaning toward a black-horned or Forbes’s, despite the contradictory song, habitat and wing proportions, because I have never heard of broad-wings having such dark legs and antennae. Here is another thing to watch out for in future seasons: here at the northern edge of an expanding range, could there be new variants popping up among the broad-winged tree crickets? Alternatively, how often do the songs of black-horned/Forbes’s converge on those of broad-wings?
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November 6, 2009 at 7:12 am (birds, botany, dragonflies and damselflies, insects (other), mammals, reptiles and amphibians, singing insects)
Tags: Asclepias, aster, Baltimore oriole, black-capped chickadee, blue jay, blue-gray gnatcatcher, brown-headed cowbird, chimney swift, chipping sparrow, common grackle, downy woodpecker, eastern bluebird, eastern kingbird, eastern phoebe, Erigeron, Eupatorium, European starling, house wren, mallard, Mayslake, northern flicker, Polygonum, Ranunculus, red-bellied woodpecker, red-winged blackbird, robin, Solidago, song sparrow, tree swallow, white-breasted nuthatch
by Carl Strang
Earlier this week I completed my first year of observations at Mayslake Forest Preserve. Many of the posts in this blog, which also is approaching its first birthday, have shared pieces of Mayslake’s ongoing natural history. It’s appropriate to look back at what I have learned there so far. Today I’ll simply share some numbers, the counts of species I have observed on the preserve to date.
Resident vertebrates include 14 species of mammals, 4 reptiles and 3 amphibians (though additional frogs have been observed at Mayslake by others in recent years). The bird species count is 130, many of which were migrants passing through. I saw evidence for successful nests, fledging at least 1 young, in the following 21 species: eastern bluebird, chimney swift, song sparrow, house wren, eastern kingbird, robin, northern flicker, blue jay, eastern phoebe (cowbird produced), chipping sparrow (cowbird produced), downy woodpecker, red-winged blackbird, red-bellied woodpecker, common grackle, black-capped chickadee, tree swallow, European starling, blue-gray gnatcatcher, Baltimore oriole, white-breasted nuthatch, mallard.
The insect species count is only 97 so far, but most of these belong to 4 groups to which I have directed most of my attention: 26 species of singing insects, 29 dragonflies and damselflies, 24 butterflies and moths, and 6 bumblebees.
Likewise my attention to Mayslake’s vegetation has been limited to certain groups of vascular plants. These include 49 trees (including those planted by landowners prior to forest preserve acquisition), 23 vines and shrubs, and 184 forbs. I’ll elaborate the last a little by mentioning genera represented by 4 or more species: so far I know of 4 Asclepias (milkweeds), 6 Aster, 4 Erigeron (fleabanes), 5 Eupatorium (a diverse genus including Joe Pye weeds, bonesets, and white snakeroot), 4 Polygonum (knotweeds), 5 Ranunculus (buttercups), and 7 Solidago (goldenrods).
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October 30, 2009 at 6:07 am (methods, singing insects)
Tags: common true katydid, Cricket Crawl, fall field cricket, greater anglewing, Gryllus pennsylvanicus, Microcentrum rhombifolium, New York, Pterophylla camellifolia, singing insect monitoring
by Carl Strang
When I began to study singing insects a few years ago, one of my hopes was that I would be able to develop protocols for a monitoring program. I was a participant in the dragonfly monitoring group, and I was aware of hearing-based monitoring programs for frogs and breeding birds. In subsequent years I have found that there is no clear way to comprehensive, all-species monitoring of singing insects. Because of the odd pitch ranges and harmonics, different people hear insect songs differently. For example, older people like me begin to lose their capacity to hear higher pitches, and need to rely on devices like the expensive Songfinder to hear some species. There are many insect songs to learn, in comparison to relatively few frogs and toads. Though the number of breeding bird species is greater, birds are popular. Few people will make the kind of effort needed to learn so many insect songs.
I was interested, therefore, to learn of a group in the New York City area which has come up with a different approach to singing insect monitoring. They call it the Cricket Crawl. They selected a date, September 11, on which they asked people to go out at night and listen to insect songs for one minute at one or more places, then report locations and species heard to the web site. Key to their plan was limiting the focus to seven species of insects with loud, distinctive songs that nearly everyone can hear. They acknowledged that others “form the background of soft churrs and trills that emanate from a series of different small ground and tree crickets.”
While results are not complete as of this writing, Sam Droege and other organizers immediately picked several patterns from the data. For instance, the fall field cricket (photo above of a female) proved to be the species most tolerant of the broad range of urban environmental conditions. The most common katydid was the greater anglewing (photo below).
The species of greatest interest was the common true katydid, which historical data indicated at one time had become scarce or even extirpated locally. The September survey found several local populations, some of which may have become established from eggs transported on nursery stock from other parts of the country.
As I continue to ponder possibilities for insect song monitoring, the success of the Cricket Crawl will remain in mind as worth considering.
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October 21, 2009 at 6:10 am (singing insects)
Tags: coneheaded katydids, Danada, Nebraska conehead, Neoconocephalus ensiger, Neoconocephalus nebrascensis, Neoconocephalus retusus, Neoconocephalus robustus, Parson's Grove, robust conehead, round-tipped conehead, sword-bearing conehead
by Carl Strang
The singing insect season is drawing to a close, and I have not mentioned one group to which I devoted some attention this season. The coneheaded katydids are a fairly diverse group of relatively large katydids characterized by cone-shaped structures that rise from the tops of their heads.
This is a Nebraska conehead. Its song consists of loud, shrill buzzes about 1.5 seconds long, with 1-second pauses between. It sings starting at dusk, in habitat that in my experience always has bushes and usually trees. The only location I have found so far with more than 3 or so singing individuals is Parson’s Grove at Danada Forest Preserve. The scattered bushes against the savanna edge seem to be ideal for this species.
There are two common, widely distributed coneheads in DuPage County’s meadows and prairies. The first to start singing, in the second half of July, is the sword-bearing conehead.
Its rapidly ticking song has been compared to the sounds of a distant steam engine or a sewing machine. The other common meadow species is the round-tipped conehead.
As you can see, these katydids look much alike. The round-tipped has a relatively short cone with a small black area at the tip (compare to the longer cone with a nearly all black surface on the Nebraska conehead, above).
This one is more of a late season species, starting up in the second half of August and continuing through October. Its song to my ear is much like that of the Nebraska conehead, except that it has very long continuous buzzes rather than interrupted ones.
The possibility that I need to clear up is whether the robust conehead also is present. Its song is continuous, like that of the round-tipped, but reportedly is much louder and at a lower pitch. Its similar cone typically lacks the black tip, and body size is larger. I may have heard some of these at night while driving in past years, but so few in 2009 that I will have to hold this possibility for investigation until next year.
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October 16, 2009 at 6:47 am (methods, singing insects)
Tags: Conocephalus brevipennis, Conocephalus fasciatus, Mayslake, short-winged meadow katydid, slender meadow katydid, Songfinder
by Carl Strang
In an earlier post I wrote about how the soprano recorder, a musical instrument, has been helpful in my singing insects research. This summer I acquired another gadget and began exploring its potential.
This is the SongFinder. Microphones on each earpiece take in sounds, the electronic box alters them by reducing their pitch, and sends the results back to the earpieces. You can slow sound frequencies by one-half, one-third or one-fourth. You also can set threshold sound frequencies below which the device does no alteration. At several hundred dollars, this is not an impulse buy. I waited a couple years until I had made a good start on the insect songs I could hear unaided. But now I am at the point where I want to begin surveying additional species, mainly small meadow katydids in the genus Conocephalus, whose songs are too high-pitched for me to hear without help.
This is a short-winged meadow katydid. I never had heard its song until I used the SongFinder. The song has the typical meadow katydid tick-and-buzz pattern. In this case the song is very brief, lasting one to two seconds depending on temperature. The songs repeat continuously with no gap between them. The buzz has an exceptionally rattling quality, and the 2-3 ticks are very fast. At Mayslake Forest Preserve on a recent day I heard dozens of short-winged meadow katydids whose songs vanished from my hearing when I turned off the SongFinder. Thanks to the stereo design, I found I can locate the direction from which an altered sound is coming and trace it to the singer.
I have done my best to protect my hearing. I avoid louder music concerts, and use ear plugs when necessary, for instance in 2007 when, at their peak, periodical cicadas at mid-day were chorusing so loudly that my ears hurt without protection. Even with these precautions, age gradually has eroded the upper range of pitches I can hear. The SongFinder was created for birders and other natural history enthusiasts for whom sounds are an essential part of our aesthetic.
As I continue to make use of this device in future years I look forward to hearing additional species, such as the slender meadow katydid (though not the individual in the picture, which is a female).
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October 6, 2009 at 6:47 am (singing insects)
Tags: Blackwell, broad-winged bush katydid, counting song, curve-tailed bush katydid, Scudderia curvicauda, Scudderia pistillata, Scudderia texensis, Springbrook Prairie, Texas bush katydid, Upper Peninsula
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).
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.
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.
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.
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September 29, 2009 at 5:54 am (singing insects)
Tags: Brookfield Zoo, cedar, cerci, long-spurred meadow katydid, Orchelimum sylvaticum
by Carl Strang
Recently I spent a day at the Brookfield Zoo, which remains to this point the only place where I have found long-spurred meadow katydids in northeast Illinois.
The above photo is inverted; the insect was clinging to the underside of a cedar twig. This is the first individual I found two years ago. I’d noticed its song as that of a meadow katydid, but unlike other species I’d encountered. The buzz has a loose rattling quality, and the ticks that precede the buzz sound like elements of the buzz rather than the sharper ticks produced by other meadow katydids. The overall effect is that the song sounds like an accelerating buzz. I spent some time with that first individual, and managed to get some photos of his cerci.
The cerci are the yellow structures at the tip of his abdomen. The long inward-projecting forks of the cerci give the species its name. References indicate that long-spurred meadow katydids like cedars, but so far I have not found them in DuPage County. On my recent zoo visit I found a couple individuals singing not from cedars but from herbaceous flowerbeds. I haven’t given up on them, and continue to seek them wherever there are cedars.
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September 24, 2009 at 6:18 am (singing insects)
Tags: Allard's ground cricket, Allonemobius allardi, Allonemobius griseus, Camnula pellucida, Carolina ground cricket, Chloealtis abdominalis, Chortophaga viridifasciata, clearwinged grasshopper, crepitation, dog day cicada, Eunemobius carolinus, fall field cricket, gray ground cricket, greenstriped grasshopper, Gryllus pennsylvanicus, Illinois Beach State Park, Michigan, stridulation, Taquamenon Falls, Thomas's broad-winged grasshopper, Tibicen canicularis, Upper Peninsula, Whitefish Point
by Carl Strang
The third goal of my Upper Peninsula trip last week was to study the singing insects there. Compared to northern Illinois, the singing insect fauna was very limited. At night the campground at Tahquamenon Falls State Park was quiet, except for the amazing snoring of one of my neighbors, thankfully only for one night. During the day the principal singing insect in the forest was the dog-day cicada.
Open areas such as Whitefish Point had more to offer. I was especially pleased to find that gray ground crickets are common there. Like all ground crickets these stayed well hidden. Here is typical habitat.
This species is known from dunes areas around southern Lake Michigan, but the only time I was at Illinois Beach State Park listening for them was a windy day and I could not hear them clearly. At Whitefish Point I easily distinguished their song. Though the trills seem composed of discrete notes like those of Allard’s ground cricket, they are at least three times faster (Allard’s were there as well, making comparison easy). Also, the trills were not continuous but rather were interrupted by brief pauses that were spaced regularly in some individuals but at varying intervals in others. In addition to Allard’s, familiar crickets at Whitefish Point were fall field crickets and Carolina ground crickets.
Whitefish Point also was home to two singing grasshoppers that represented the two forms of grasshopper song production. One of them was a crepitating species like Illinois’ greenstriped grasshopper. My references point to the clearwinged grasshopper, Camnula pellucida, as the identification, though I am not certain.
In the photo the male is on the left. Crepitation is sound production by the rattling or snapping of the wings in flight. In this species the rattle is much louder than that of the greenstriped grasshopper. Clearwinged grasshoppers occupied the more open dunes areas. The other form of sound production is called stridulation. A common grasshopper that stayed close to woody plants at Whitefish Point produced loud “zuzz-zuzz-zuzz” sounds with this method. My best stab at identification is Thomas’s broad-winged grasshopper, Chloealtis abdominalis.
The black areas on the sides of the pronotum seem to point to that species. Another photo, taken just as the grasshopper turned to put some distance between itself and my camera, shows that from behind the legs have a lot of red on them.
In stridulation, both legs are lifted and lowered at once, and rows of pegs on them rub against the folded wings to produce the sound.
I also found broad-winged bush katydids at Whitefish Point, but I will hold that discussion for a later time.
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September 13, 2009 at 10:04 pm (methods, singing insects)
Tags: block count, Davis's tree cricket, narrow-winged tree cricket, Neoxabea bipunctata, Oecanthus exclamationis, Oecanthus fultoni, Oecanthus niveus, recorder, snowy tree cricket, two-spotted tree cricket
by Carl Strang
For the most part in this blog I am trying to model methods of inquiry that don’t rely on technology. Our human senses have their limitations, but we can gather enough information through them to answer a lot of questions about our surrounding wild world. Nevertheless, there are occasions when gadgets can help. Today I will feature one of those I have found useful in my field studies of singing insects: my soprano recorder.
I don’t have perfect pitch, but I have a reasonably good ear. I have found the recorder to be especially helpful as I tackle the problem of the arboreal tree crickets (outlined in my earlier post on one of them, the two-spotted tree cricket ). This season one of my goals has been to sort out the songs of the two-spotted, narrow-winged and Davis’s tree crickets. I was encouraged when I noticed that Elliott and Hershberger, in their recent book on singing insects, indicated that these three species should have distinct pitches in their songs. Highest should be the two-spotted, at 3.5 kHz (kilohertz, a quantitative sound frequency measurement), which translates to a pitch of A, the fourth A above middle C. In the middle should be the narrow-winged tree cricket, at 3 kHz or approximately F-sharp, the fourth F-sharp above middle C, 3 half-tones below the two-spotted. I noticed, incidentally, that the distinctive song* of the snowy tree cricket also is indicated to be at 3 kHz, and so I had hopes that this would provide a rough and ready field standard. The lowest of the arboreal tree crickets, according to Elliott and Hershberger, is the Davis’s tree cricket, at 2.5 kHz. This translates musically to the fourth E above middle C, distinctly lower than any of the others. So, recorder in hand, I set forth.
Snowy Tree Cricket
Two caveats quickly became clear. First, the pitch of a given species is subject to change with environmental temperature, rising and falling as the temperature rises and falls. Second, I have to keep in mind that my own hearing may not well match the measuring devices used to provide the information in that book. In general all species sounded, to my ear, a good 3 tones lower than Elliott and Hershberger suggested.
I have found that to my ear, both two-spotted and narrow-winged tree crickets have songs distinctly higher pitched than that of the snowy tree cricket. At a given temperature, the two-spotted sings one-half to a full tone higher than does the narrow-winged. However, at a given general temperature, narrow-wings range over half a tone of pitch or more. Whether this is because the microclimate is different where individual crickets are singing, or whether this is something they are controlling, I cannot say. It means, though, that I have to rely as much or more on the temporal pattern of the song to distinguish these two species.
Narrow-winged Tree Cricket
Narrow-wings sing with a steady pattern of trills and spaces, with trills of equal lengths and spaces of equal lengths, and the spaces are significant at a second or so duration. Two-spotteds sing at a little higher pitch on average, have trills of varying lengths including some often lasting well over 5 seconds, usually with at least some pauses that are very brief, as though catching a quick breath.
I recently heard, on my neighborhood block count, what I believe must have been a Davis’s tree cricket. The insect was high up in a tree. Its trills were variable but generally very long, with only occasional odd interruptions. Spaces were short. Significantly, the pitch was down at A-flat, low for the temperature, which was 70F. Based on my recorder tests, at that temperature I would expect snowy tree crickets to be singing at B or C, two-spotteds at the E above that, and narrow-wings at C to E. So, the recorder is a helpful tool, but in distinguishing the songs of these crickets I find that the pattern of their song is more reliable than the pitch.
*You know the song of the snowy tree cricket, even if you live outside its range. In the movies, whenever the director wants to convey a calm nighttime mood, there will be a snowy tree cricket in the sound track. The song is a pulsing tone, varying with the temperature so that if you count the notes in 15 seconds and add 40, you have the temperature in degrees Fahrenheit. Though the narrow-winged tree cricket’s song likewise is a regular pulse, the tones are on the order of 2 seconds’ duration with a 1-2-second space between. Unless the temperature is very cool, the snowy’s song is much faster.
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September 10, 2009 at 6:12 am (singing insects)
Tags: Allard's ground cricket, Allonemobius allardi, Anaxipha exigua, Blackwell, Say's trig
by Carl Strang
The trigs are a group of tiny crickets which, like the ground crickets, are heard much more than they are seen. The common species in northeast Illinois is Say’s trig. Here’s a female; the short curved ovipositor extending from her abdomen identifies her gender.
Finding the male in the next photo required an extended slow stalk. His beautiful trill, accurately described as “silvery” by Elliott and Hershberger , was well amplified by the little cluster of dead leaves where he was hiding, but difficult to locate. I coaxed him out onto the white oak leaf lobe which provides some scale, and returned him to his spot after taking his picture.
Thanks to that ventriloquial quality I had not realized in my first season of singing insects study that these trigs sing mostly up off the ground. I thought I was hearing a ground cricket. Then in my second year I encountered a bunch of Say’s trigs in the tall grasses at Blackwell Forest Preserve, took a male home so I could hear and record his song, and returned him after confirming the identification. Since then I have found them practically everywhere there is dense or tall vegetation (including my own garden!). They begin to sing in numbers in late July or early August, and continue to mid-October or November. Their trill is similar to that of Allard’s ground cricket, but the notes are more run together rather than being distinctly staccato, and usually are coming from a source above the ground. The sound quality also is different. Recordings of Say’s trig songs can be heard here or here .
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