Singing Insects Indicate Ecosystem Diversity

It is an unmistakable sound on late summer evenings with windows wide open–the hum, chirp, trill and buzz of insects. These are the night singing insects, described by Dr. Carl Strang as the cicadas, katydids, crickets and three subfamilies of grasshoppers in which males produce sound displays so females can find them and humans can hear them.

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The Butternut Creek Nature Sanctuary protects * habitat type*. Photo by Joe Roti

As a naturalist with the Forest Preserve District of DuPage County, IL and a little more “ear oriented than most”, Carl took an interest in the sounds of nature, including those made by insects. His curiosity led him to learn how to identify insects by sound, both by ear and by recordings using computer analysis. In 2006, he initiated a long-term general survey of singing insects in a 22-county region stretching from southeast Wisconsin, northeast Illinois, northwest Indiana and into southwest Michigan. In 2018, his annual census included a stop at MNA’s Butternut Creek Nature Sanctuary in Berrien County.
“There are about 100 species in the region and are found in every habitat except open water,” Carl explains. “They are relatively easy to survey because of the sounds, you don’t have to trap them or put in a lot of time with specialized techniques.”

 
“The night singers are not keystone species, most of them are not dependent on a particular plant, nor are they the main food for other animals,” he continued. “Their main value is as indicators of ecosystem quality and diversity.”

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Dave Cuthrell “sweep-netting”, a method to search for tree insects.

What distinguishes this group of insects, according to Carl, is that they are not big travelers, they are limited in movement, and don’t fly very far. “Singing insects can be a good indicator of the health of a system. With some animals you can build it, that is restore habitat, and they will come,” he says, “That’s not so true with singing insects.” Carl believes habitat restoration is important, but not at the expense of protecting and maintaining high quality habitat of critical sizes.

 
Indeed, Carl’s survey is yielding interesting results. 50 to 100 years ago, early work in the field documented species occurrences. Fast forward to current day and some that Carl expected to find or should have found, he is not finding. Some very common—like the dusky-faced meadow katydid—occurred in every marsh 50 years ago. Now he is only finding them in marshes free of invasive plants. “Only a couple of singing insects can live in that kind of habitat,” according to Carl. Habitat degradation and loss is a big factor in declines of singing insects where they once occurred.

 

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Wendy Partridge & Lisa Rainsong look for a long-spurred meadow katydid at Indiana Dunes State Park.

Carl is also finding species that are in his study area now but were not here 50 years ago. Almost all these have come up from the south, he says. A warming climate may be a likely factor, although very tough to prove scientifically.

 
On a surprisingly cool and rainy day in August of 2018, Carl’s work took him to Butternut Creek Nature Sanctuary. There he accompanied Nancy Collins, a citizen scientist who is rapidly becoming a recognized tree cricket expert. They stopped to listen and look for the tamarack tree cricket, a species of special concern in Michigan and one that has been known to occur at the nature sanctuary. According to the Michigan Natural Features Inventory, the tamarack tree cricket inhabits dense to open tamarack swamps and fens. Carl and Nancy identified 14 singing species there—but no tamarack tree cricket.

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Tamarack tree cricket. Photo by Dave Cuthrell.

He is not sure whether it was the cool and wet weather that day, or if they were not there at the right time of the season, or if they hit a low period in the cyclical population cycles that insects experience. “The habitat at Butternut Creek looks fine and healthy with lots of tamaracks,” Carl says. “It is definitely worth getting back in there again.”

 

Carl plans to stop back at Butternut Creek this summer to listen for tamarack tree crickets as he conducts his annual 22-county sweep. And starting in late July until late fall when the weather turns cold, listen for the night chorus of singing insects—and know that scientists like Carl and Nancy are listening too.

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Coastal Sanctuaries Protect Changing Shorelines

With ever-fluctuating weather conditions, and uncertainty in how climate change will affect water levels in the Great Lakes basin, the work that MNA is doing to protect habitat for rare, threatened, and endangered species is now more important than ever.

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Volunteer Ashley Schilling uses her hand as a measurement for the dwarf lake iris.

One of several coastal sanctuaries that MNA currently maintains is the Spitler Shore Nature Sanctuary in Presque Isle County. This 50-acre sanctuary includes more than 1,500 feet of Lake Huron shoreline, and contains populations of the federally threatened dwarf lake iris. This sanctuary’s habitat, like much of the Great Lakes shoreline, is at risk from extreme and unpredictable fluctuations in water levels, affecting much more than just its magnificent sunrise views.

During the period between 1998 and 2012, Lakes Michigan and Huron experienced persistently low average water levels. This was due in large part to increased evaporation – to which the lakes are susceptible whenever they are not covered by ice. But the winter of 2013-14 brought extended periods of extreme cold, resulting in increased ice cover and protecting the lakes from the much of this evaporation. Since that time, all of the Great Lakes have risen to record-high average levels, the product of both limited evaporation, and heavy precipitation and runoff from the many rivers and streams that feed the lakes. Water levels in 2019 have proven to continue this trend of new record highs, with meteorologists having estimated a 10-inch rise on Lakes Michigan and Huron through July (representing 8 trillion gallons of water) – the lakes were recorded at 13 inches above their 2018 levels, by the end of June.

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Many shipwrecks and their associated debris were newly uncovered during this reduction and influx of water along the shorelines of Huron and Michigan. The photo here shows some of these shipwreck timbers which today rest peacefully once again underwater, discovered by a father and daughter from Camp Chickagami. Photo by John Porter.

These extremes have had profound effects on developed shoreline statewide, with much of Belle Isle being inundated with rising St. Clair River water, and roads in the Upper Peninsula at risk of eroding into Lake Superior. The impact on non-developed shoreline, like that found in Spitler Shore Nature Sanctuary, is yet to be realized, but it is now more clear than ever that these spaces need protecting, so that they can continue to support the diversity of plant and animal life required for a healthy ecosystem.

You can learn more about MNA’s statewide nature sanctuaries online at michigannature.org.