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.

 

Sound Ideas: Katydids that “Katydid”

by Carl Strang

The name “katydid” has come to cover a wide range of singing insects, most of whose songs do not sound anything like that name would suggest. Today I wish to share recordings of two species which seem to say something like that name. Both are common in the region. First up is the oblong-winged katydid:

Oblong-winged katydid

Oblong-winged katydid

The next recording is of a common true katydid. Though this individual has only two syllables per song, some have three to match the syllables in “katydid,” and others have 4 (“katy didn’t”) or more.

Common true katydid

Common true katydid

Ah, summer.

 

Sound Ideas: Japanese Burrowing Cricket

by Carl Strang

One of the unexpected findings from the field season just past was the discovery of Japanese burrowing crickets at Bendix Woods in St. Joseph County, Indiana.

Japanese burrowing cricket

Japanese burrowing cricket

As described earlier, there is a well-established population of this exotic species in the gravel-filled medians dividing parking lots and drives in the central part of the park. They are well buried, and it was only their distinctive songs that gave them away.

The chirps are distinctly buzzier than those of the fall field crickets that were singing nearby. Here is a fall field cricket recording from 2006 for comparison.

Listening to it, I’m getting a warm reminder of summer. Common true katydids, a striped ground cricket, and wall-of-sound tree crickets and other ground crickets are in the background.

 

McHenry County Exploration

by Carl Strang

On Friday I took a vacation day to check out some sites in McHenry County for their singing insect potential. I saw parts of 4 widely scattered Conservation Areas (their equivalent of Forest Preserves), and picked up 4 county records for my study along the way.

Within minutes of arriving at the first site, Elizabeth Lake, I spotted this bush katydid feeding on a tansy flower head.

Within minutes of arriving at the first site, Elizabeth Lake, I spotted this bush katydid feeding on a tansy flower head.

The small body size, and the shape of the ovipositor, identified this female as a fork-tailed bush katydid.

The small body size, and the shape of the ovipositor, identified this female as a fork-tailed bush katydid.

That was not one of the county records, but I did pick up two at that site: Forbes’s tree cricket, and slender meadow katydid.

The area with the greatest potential proved to be Hickory Grove-Lyons. These areas are a political oddity. Though the Lyons portion is in Lake County, it is cut off by a bend of the Fox River, and so managed by the McHenry County Conservation District.

A boardwalk leads through a high quality marsh at Hickory Grove. Other marshes and woodlands in this, and the adjacent Lyons area, are priorities for future exploration.

A boardwalk leads through a high quality marsh at Hickory Grove. Other marshes and woodlands in this, and the adjacent Lyons area, are priorities for future exploration.

The year’s first Texas bush katydids, which also provided a county record, were singing in that marsh. The fourth county record, common true katydid (which seems oddly uncommon in McHenry), came at a good-looking forested preserve, Coral Woods. I look forward to return visits to some of these sites.

 

Encounters Along the Way

by Carl Strang

As another season of field research into the region’s singing insects winds down, I am starting to look back at the highlights. Some of these were chance encounters that provided new photo opportunities. For example, there was a weakened common true katydid I found on a trail at Waterfall Glen in broad daylight. I didn’t have a good photo of the species, and posed him after removing him from the hazardous trail.

Unfortunately I neglected to place his hind legs in a natural position.

Unfortunately I neglected to place his hind legs in a natural position.

Another species for which I want a better photo is the handsome trig. Some were singing on a cloudy day down in Fulton County, Indiana, and one came out in the open, but the low light resulted in a less than sharp image.

Tiny but colorful, the handsome trig lives in the southern part of the region I am surveying.

Tiny but colorful, the handsome trig lives in the southern part of the region I am surveying.

The Indiana Dunes area provided several photographs.

This oblong-winged katydid female was emitting single clicks in response to the more complex songs of nearby males.

This oblong-winged katydid female was emitting single clicks in response to the more complex songs of nearby males.

A four-spotted tree cricket had escaped from my grasp before I could photograph it. While looking for it on the ground where it seemed to have gone, my headlamp revealed something better.

A female tinkling ground cricket, only the second member of the species I have seen (despite hearing hundreds).

A female tinkling ground cricket, only the second member of the species I have seen (despite hearing hundreds).

A similar encounter came when I was trying to get a better photo of a melodious ground cricket at Indiana Dunes State Park. Digging through the leaf litter in the area from which a male’s song seemed to be coming, I turned up a female ground cricket.

When I examined the photos, though, I saw that the palps were white. This was a female confused ground cricket, another species that was singing in the area, and the first female confused I have seen.

When I examined the photos, though, I saw that the palps were white. This was a female confused ground cricket, another species that was singing in the area, and the first female confused I have seen.

One of the last places I visited this year was the Bong Recreation Area in Kenosha County, Wisconsin. The prairie area there is extensive, and has a good population of common meadow katydids.

Despite its name, the common meadow katydid is much less frequently encountered than two of its congeners, the gladiator and black-legged meadow katydids.

Despite its name, the common meadow katydid is much less frequently encountered than two of its congeners, the gladiator and black-legged meadow katydids.

There were a few broad-winged bush katydids in the prairie, but I wasn’t successful in stalking one. This Texas bush katydid had to substitute.

There were a few broad-winged bush katydids in the prairie, but I wasn’t successful in stalking one. This Texas bush katydid had to substitute.

Such encounters, sprinkled through the field season, make for good memories.

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.

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.

Block Count Summary

by Carl Strang

Neighborhood block counts are a survey method I have developed in my singing insects study. They consist of walks around the block in my residential neighborhood in Warrenville. I record the time and temperature, and count only the insects whose individual songs I can distinguish from the general background of tree cricket and ground cricket songs. I try to include a mix of times, especially early in the season to include cicadas, but concentrate most of the effort after dark when most species are singing. The overall species count in 2011 was 14 (no new species this year).

One of the streets on the block.

Most of these insects do not occur in high enough numbers to permit statistical comparisons between years. The high counts for each species this year were as follows: 1 for fall field cricket, jumping bush cricket, Say’s trig, and Davis’s tree cricket; 2 for Allard’s ground cricket and dog day cicada; 3 for snowy tree cricket, 4 for narrow-winged tree cricket, 5 for common true katydid, 8 for two-spotted tree cricket, 10 for Linne’s cicada, 14 for Carolina ground cricket, 16 for greater anglewing, and 26 for striped ground cricket. Most of these are typical of the past five years. Apart from statistical comparisons to follow, there seems to have been a decline in fall field crickets over that period (high counts of 5 in 2007, 4 in 2006, and 1 in the recent years, but in 2011 that count was on only one occasion).

Only three species occur consistently in large enough numbers to justify statistical comparisons between years. There never have been statistically significant differences between adjacent years in striped ground cricket counts, and the same was true in this year’s comparison with 2010 (overall medians 14.5 in both years; Mann-Whitney U-test, z = -0.14, P>0.01). Carolina ground crickets likewise were not different (median 4 in 2010, 7 in 2011; z = -2.07, P>0.01). Greater anglewing counts did show a statistically significant increase over last year (median 1 in 2010, 4 in 2011; z = -3.30, P < 0.01), and in general they and the fall field crickets have been the most volatile.

Peak Singing Insect Season Begins

by Carl Strang

By this point in the season we are hearing nearly all the common singing insects in northeast Illinois. First song dates on the whole have been in line with those of recent years, but a few have been relatively late and one was comparatively early.

Snowy tree cricket

My own first observations of singing males typical of residential neighborhoods have included Carolina ground cricket (19 July), common true katydid (also 19 July, a relatively early start for that species), Allard’s ground cricket (22 July), snowy tree cricket (29 July), fall field cricket (30 July, a relatively late start but I had been out of town for a week), two-spotted tree cricket (31 July), Say’s trig (31 July), and greater angle-winged katydid (4 August).

Greater angle-winged katydid

I didn’t get into forests at night until the Roger Raccoon Club campout, so my first date of August 3 for oblong-winged and rattler round-winged katydids has limited meaning. Another forest species that may have started up before my first observation of August 2 was the confused ground cricket.

Black-legged meadow katydid

Our most common large meadow katydid, the black-legged, started up around August 2, a relatively late start for this wetland-edge insect.

Insects at the Campground

by Carl Strang

The overnight campout at Waterfall Glen Forest Preserve that concludes the Roger Raccoon Club provides opportunities to observe various aspects of natural history. Last week the campground’s gravel parking lot, damp from overnight rain, apparently held a good supply of dissolved minerals, as it attracted butterflies representing at least 5 species.

Most remarkable was this giant swallowtail, a species uncommon in DuPage County but encountered regularly in small numbers at Waterfall Glen. I believe their main food plant in northeast Illinois is prickly ash, an infrequent shrub.

After dark an orchestra of singing insects filled the forest with sound. Dominant that night were large numbers of common true katydids, with smaller numbers of scattered two-spotted tree crickets, rattler round-winged katydids, and oblong-winged katydids. I needed a photo of the last species, and was able to find one singing close to the edge of the woods.

This oblong-winged katydid is holding his wings apart in singing position. Rasp and file structures on the brown portions of the two wings are rubbed together to produce the song.

As it happened, some of the kids found another male on their tent in the morning. I gave them a brief lesson about it, and took another set of photos.

Here the wings are in their normal folded position.

Some of those singing insects represented my first observations of their species this year.

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