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 29, 2009 at 6:15 am (invertebrates (other))
Tags: nightcrawler, Lumbricus terrestris
by Carl Strang
Yesterday I described my check of garlic mustard seedling survival in study plots established last spring. While carefully removing fallen leaves to expose the seedlings for counting, I found that many of the leaves seemed stuck in the ground. Furthermore, these were in tiny clusters, and instead of the petiole (stem) end, usually the tips were imbedded.
In the above photo you can see how the tip of the oak leaf seems stuck in the ground, and a couple of other leaf petioles radiate out from the same spot. As I removed these leaves, I found that they were in clearly defined holes in the soil.
The holes were uniform in size, and I was finding a lot of them.
I soon realized what must be the case, and sure enough began to spot the ends of nightcrawlers retreating down the holes as I exposed them. Here is one protruding from its hole.
The conclusion seems inescapable that these large earthworms actively are pulling leaves into their tunnels and consuming them. Typically a hole had several leaves, with various proportions of their lengths having gone into the holes and with the ends missing. I hope the photos are making this clear. Certainly the feel of the clustered leaves stuck in the holes as I cleared the study plots was striking. I never would have encountered this if I had not been pursuing the garlic mustard seedling check. Inquiry leads to inquiry.
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October 27, 2009 at 5:38 pm (botany, restoration)
Tags: Alliaria petiolata, experiment, garlic mustard, invasive plants, seedling survival
by Carl Strang
In the spring I began a study of how garlic mustard, a harmful exotic biennial, might best be controlled by manual means. In small areas where the plant is just beginning to invade, and where use of herbicides is undesirable, it is possible to uproot or clip the second-year plants. Results so far indicate that pulling is more effective than clipping, but there is a timing variable to investigate, and I need also to determine whether pulling stimulates an increased germination of seedlings in the following year.
Last week I returned to my study plots to count seedlings at the end of their first season. As the above photo shows, some tree and shrub leaves had fallen, so I carefully removed these to make sure my seedling counts were complete.
I had expected some attrition through competition, but was surprised at the numbers of seedlings that had died. Every single one of the 27 square meters in the study plots showed big drops in numbers of seedlings, even in cases where there were so few that competition between them would seem to be negligible. Where in May seedling counts ranged from 12 to 345 in the square meter areas, in October the counts were 0 to 55. Especially dramatic were the control squares, in which second-year plants had been allowed to proceed to fruiting before I clipped them. There, seedlings had looked weak, but plenty still remained in May. However, the total of 214 seedlings in May had dropped to only 3 seedlings in the 9 square meters of the control treatment by October. Apparently their inhibition by the second year plants had been too great for them to overcome. Attrition in pulled treatment squares had been from 747 to 236 between May and October, and the corresponding numbers for clipped treatment squares were 1002 and 107. Statistical computations supported the difference between controls and both treatments in October counts, but indicated no statistical significance between the two treatments.
Now I wait for spring. I plan to set up new study plots next year, but will apply the same treatments a month later, to see what difference timing makes. I also will return to this year’s plots. I want to follow this year’s seedlings through to their fruiting times, and to see if the numbers of new seedlings in those squares support or reject the notion that pulling increases seed bank germination.
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October 23, 2009 at 6:18 am (plant-eating insects)
Tags: bitternut hickory, Carya cordiformis, defensive mimicry, eye spots, Geranium maculatum, leaf miner, Meacham Grove, Pachyschelus purpureus, sibling species, Ted C. MacRae, wild geranium
by Carl Strang
Last winter I described a leaf-eating beetle, Pachyschelus purpureus, which has a diet contrary to the usual rules governing leaf-eating insects. My past observations have been that, instead of eating a variety of tree leaves, or focusing on a group of herbaceous plants with similar defensive chemistries, this beetle scrapes holes in the surfaces of both wild geranium and bitternut hickory leaves at Meacham Grove Forest Preserve.
I was interested, then, to read in Missouri entomologist Ted C. MacRae’s blog, Beetles in the Bush, that he has studied beetles in genus Pachyschelus. Through e-mail correspondence I have learned from him that purpureus larvae are leaf miners, known to develop in geranium leaves. Ted encouraged me to continue observing these beetles, to see if indeed there is a particular connection between them and bitternut hickory.
The above photo I took in the late summer. I found only a few scattered Pachyschelus this year, and though they were resting only on geranium and bitternut hickory leaves, none were feeding. Thanks to Ted I now know that purpureus adults are known to feed on a variety of tree leaves. My observations simply may be of beetles taking a bedtime snack before finding winter shelter. In the spring they will emerge and lay eggs on larval host leaves. I want to continue studying this beetle at Meacham Grove, however. I want to learn to recognize their mines. Our expectation is that these will be limited to geraniums, but if I were to find them in bitternut hickory as well, that would open the possibility that incipient sibling species, separating to specialize on two separate larval hosts, may be evolving.
Incidentally, take another look at that last photo. While searching for the beetles this year I was struck by the white spots on the elytra, how they resemble eyes (complete with antenna-like extensions). A bird grabbing for the apparent head end might find its beak sliding off the hard pointed tail end of the beetle, which then could escape by flying away in the opposite direction, its dark color in the shaded forest no longer highlighted against a pale leaf.
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October 22, 2009 at 7:15 am (birds, botany, ecology)
Tags: Aesculus glabra, cedar waxwing, common buckthorn, European highbush cranberry, false Solomon's seal, food mimicry, mastodon, mutualism, Ohio buckeye, Rhamnus cathartica, robin, seed dispersal, Smilacina racemosa, Solomon's plume, Viburnum opulus
by Carl Strang
Earlier I featured several plants at Mayslake Forest Preserve that produce fruits timed to coincide with the fall migration of berry-eating birds. This mutualistic interaction for the most part benefits the birds, through nutritional provisioning, while the plants get their seeds dispersed. Today I want to feature some outliers to this pattern. Let’s start with Solomon’s plume, also known as false Solomon’s seal.
Like many fall fruits, these advertise themselves to birds with a bright red color. When analyzed, however, the berries proved to be junk food, or perhaps are more accurately described as food mimics (White and Stiles 1985, Ecology 66:303-307). The plants save their energy, investing no nutritional value in these fruits. The ruse works, apparently, by exploiting the naïve instinctive response of first-time autumn migrants, the young of the year. A little different from this is the offering of the European highbush cranberry.
Another study (Witmer 2001, Ecology 82:3120-3130) showed that the nutritional value of these berries becomes available only when they are consumed along with a significant protein source. I was impressed to learn that, like the waxwings native to the shrub’s European home, our North American cedar waxwings ignore these tempting berries until spring, when cottonwoods or other poplars are flowering. Then the birds consume the berries along with cottonwood catkins, protein in the pollen providing access to the berries’ nutritional value.
These black berries are common buckthorn fruits. They generally are ignored by birds until late winter when, apparently, the better quality foods have been depleted. Then, robins and waxwings consume them, unfortunately dispersing the seeds throughout our woodlands. Buckthorns leaf out early and lose their leaves late, casting a shade so dense that no other plants can grow beneath them. This is why these Eurasian shrubs must be removed at the beginning of woodland restoration projects. A final fruit is of no interest to birds.
Ohio buckeyes in fact are largely ignored by animals generally. This opens the possibility that, like other trees I discussed earlier, buckeyes may have been dispersed by now-extinct mastodons and other large herbivores.
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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 20, 2009 at 6:21 am (Uncategorized)
Tags: Blackwell, Canada goose, Canada goose roosts, Hidden Lake, leucistic Canada goose
by Carl Strang
Last year I began a study of Canada goose winter roosting behavior in the western suburbs of Chicago, focusing on DuPage County. I found a number of roosting sites scattered around the county, open water places where the geese spent the nights. In the mornings the geese in the roosts dispersed, departing in groups of 20 or so, flying out to find food. In this suburban area, grazing on lawns was the primary winter fare. A period of severely cold temperatures froze three of the four largest roosts in January, and the birds departed the area rather than crowding into the remaining roost. By the time the roost areas thawed and the Canada geese returned, the time for territory establishment and migration had arrived for local birds and northern migrants, respectively, and the roosts quickly broke up.
In September I noticed familiar winter patterns, with groups of geese flying out from the Blackwell and Hidden Lake roosts as I passed them on the way to work in the mornings. On October 12 I went to the Blackwell roost to make an assessment.
Some geese, like these, already had left the roost by 7:30 a.m. and landed on nearby Silver Lake for preliminary staging. Others went straight to the lawns of Blackwell Forest Preserve and other nearby open areas to feed.
A few hundred such geese had left the roost by then, and 1000 or so remained when I reached it. I found none of the tiny cackling geese, but I did see one distant individual wearing the orange neck collar that identified it as a Hudson Bay region bird. Thus some Canada geese had arrived from the north, but the roost had not reached its 2008-9 peak of 3000 birds. It seems likely that, in addition to a continuing influx of geese from the north, smaller local roosts such as the ones I observed last year are active. If last year’s pattern repeats, those satellites will merge with the larger roosts later as the smaller lakes freeze over.
Driving back home on the 12th, I saw a group of geese landing with others already feeding on the lawn at the edge of Butterfield Road near the Warrenville town center. Among the arrivals was an individual that stood out with much paler wings and back. It proved to have white (or nearly so) body plumage, but head and neck were normal colored.
I drove to where I could park, and took some photos in the dim light.
I suspect that this leucistic individual is a bird mentioned last spring by a friend, Anne S., who has observed it for several years. If it is the same goose, it usually feeds in another nearby location I don’t typically frequent.
I am hopeful that unusual individuals like this one and the neck-collared birds will allow me to track the daily movements of Canada geese resident in our area during the winter. My main goal this year, though, will be to see if the patterns I observed last year are repeated.
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October 19, 2009 at 6:02 am (dragonflies and damselflies, geology)
Tags: bedrock, dolomite, Niagara formation, Bruce Peninsula, Hines emerald, Somatochlora hineana, dolomite prairie
by Carl Strang
Bedrock is the kind of stone found closest to the surface at a particular point on the Earth. In DuPage County our bedrock is a sedimentary rock of Silurian age called dolomite, and it belongs to the Niagara formation. A bit over 400 million years ago this part of North America was a reef-dotted shallow part of the world ocean. Over a period of millions of years, precipitates and microscopic shells, along with some larger life forms, settled to the bottom of the sea and built up a layer of sediment that later solidified into limestone, or calcium carbonate. Later, some of the calcium became replaced with magnesium atoms, changing the rock enough chemically that it was less soluble, and worthy of a new name, dolomite.
DuPage County is part of a ring of Niagara formation bedrock that extends up the west coast of Lake Michigan, forms Wisconsin’s Door Peninsula and the southern boundary of the U.P., wraps around the Canadian side of Lake Huron to divide the main lake from Georgian Bay, continues south to form the Bruce Peninsula jutting into southern Lake Huron, and eventually wraps around northern Ohio and Indiana back into northeast Illinois. Niagara Falls pours over an erosion-resistant edge of this formation, which also has outliers in Missouri and Iowa.
A few years ago I drove around Lake Huron. One of my stops was the tip of the Bruce Peninsula. There, the bedrock is at the surface. It’s possible to get a sense of what our landscape might look like in northeast Illinois if it were not covered by glacial deposits. Instead of being surfaced with crushed dolomite, our trails might run over the raw rock.
A trip to the beach would look quite different.
We might find cliffs.
Though dolomite is not as subject to solution and cave formation as limestone, sea caves might occur where waves pound the shore.
We might even find structures like the “flowerpots” that stand on Flowerpot Island off the Bruce Peninsula tip.
But as it is, there are few places in northeast Illinois where the bedrock reaches the surface.
For example, the dolomite prairies near the Des Plaines River offer rare habitat for the federally endangered Hines emerald, a dragonfly that can live only where Niagara formation dolomite provides the right water chemistry for its crayfish-tunnel-dwelling larvae.
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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 15, 2009 at 7:14 am (dragonflies and damselflies)
Tags: autumn meadowhawk, cherry-faced meadowhawk, Mayslake, saffron-winged meadowhawk, Sympetrum costiferum, Sympetrum internum, Sympetrum vicinum
by Carl Strang
It’s nice to solve a minor mystery and, in the process, gain new insights into past observations. I experienced an example of this last week after encountering an odd dragonfly at Mayslake Forest Preserve.
This small dragonfly perching on the trail near May’s Lake clearly was a meadowhawk. The abdomen, though nearly black like the rest of the insect’s body, was mainly dark red in color. I took a number of photos, and though none were perfectly sharp they allowed me to take some time with my reference books and identify it. At first I leaned toward cherry-faced meadowhawk because the dragonfly’s face was dark red, but references insisted that its abdomen should be bright red. I carefully read accounts of all the region’s meadowhawks, and found that male saffron-winged meadowhawks can become very dark with age. In the photos I found that the leading veins of the wings were dark red, the tops of the last abdominal segments were black, and the black edging on the sides of the abdomen was more in the form of a line than a string of large triangle shapes. All these characters confirmed the identification. By now my memory was prompted to go back through some photos from last year, because I remembered seeing a similarly dark meadowhawk. Here is a photo I took at Kettle Lakes Provincial Park in Ontario.
It likewise proves to have been a saffron-winged. But I also found that I had documented another dragonfly of this species at Mayslake.
This last photo, from November, 2008, I took close to the location where I saw the dragonfly last week. It proves likewise to have been a saffron-winged meadowhawk. The meadowhawks as a group tend to be late-season dragonflies, but now I have the impression that the latest of them all are this one and the autumn meadowhawk (the following photo of which I took just before encountering that saffron-winged last week).
This case again vindicates my practice of photographing any dragonfly for which I have any doubt of its species identity.
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