Landscape Ecology of Singing Insects 2: Human Influences

by Carl Strang

The previous post illustrated that the Chicago region has been a dynamically changing landscape through the recent millennia, but that now is overshadowed by the alterations our own species has made. Burgeoning human numbers have overwhelmed the planet’s ecosystems, and the native habitats described earlier mostly have been replaced by agriculture and urban growth in the Chicago region. One of the more dramatic changes is the loss of the Kankakee wetland, once described as the Everglades of the North. That vast wetland was drained for agriculture, and only a few pockets of it survive in preserves. Much of the Kankakee River in Indiana is now a straight channel with constructed high levee banks. Other smaller wetlands received similar treatment, with drainage ditches spreading across the agricultural portion of the region. This is not universally devastating to wetland species. Northern mole crickets, for instance, occasionally can be found along drainage ditches.

Drainage ditch, upper reaches of the Kankakee River, St. Joseph County, Indiana. Note farm fields on both sides.

Prairie mostly has been replaced by agricultural fields, and fire suppression has led to its invasion by woody plants. Specialists such as the prairie meadow katydid, prairie cicada and short-winged toothpick grasshopper are hard to find.

Prairie meadow katydid

My singing insects research has required a lot of driving to reach the relatively tiny surviving preserves and parks to which many of the species are now restricted. Much management effort is required in these little islands to maintain their habitats. There are exceptions, of course. Many other species have thrived under our influence. These are mainly weedy ones such as the striped ground cricket, short-winged meadow katydid and Carolina grasshopper, which do well in disturbed habitats, along with woodland edge species such as the greater angle-wing, snowy tree cricket, and jumping bush cricket, which can meet their needs in residential neighborhoods dominated by lawns and scattered trees and shrubs.

Jumping bush cricket

Habitat destruction is not the only human influence. Climate change is the probable cause of northward range expansions by several singing insect species, and it likely will lead to the extinction of the sphagnum ground cricket from the region as the sphagnum bogs dry up. Say’s cicada and some northern grasshoppers already appear to be pushed out.

Sphagnum ground cricket

Climate change isn’t simply a matter of rising temperatures, as the term “global warming” may seem to imply. Global warming is an accurate enough term, as the simplest way to measure climate change is to track the global average temperature. But the point is that our changes to the Earth’s thin skin of atmosphere are increasing its held solar energy. That energy alters patterns of atmospheric flow and the behavior of storms. Droughts, more frequent flood-causing rains, and seasonal increases or decreases in temperature that seem abnormal are examples of results we observe locally. The singing insects are forced to adjust as best they can. Droughts force sphagnum ground crickets into the wettest parts of their bogs. The severe drought of 2012 concentrated wetland meadow katydids and marsh coneheads into the small portions of the Great Marsh in the Indiana Dunes National Park that remained wet. Oblong-winged meadow katydids may be pre-adapted to such year-to-year variability. Blatchley (1920) observed that their eggs, laid in moist soil, can take 2-3 years to hatch. In my travels through the region I failed to hear a single individual in the years 2010 and 2019, but in other years they have been abundant and widespread. Some of the cicadas and other species may have similar flexibilities.

Oblong-winged katydid

People also have introduced plant species from other parts of the world which, released from the consumers and competitors which hold them in check in their native lands, have become invasive plants here. Their unfair competitive advantage has led to their displacing the region’s native vegetation in an increasing number of places. This is most evident in our wetlands. Wetland meadow katydids and other singing insects are limited to places where native wetland grasses have not been supplanted by reed canary grass, common reed, purple loosestrife, and hybrid cattails. These invasive plants are proving difficult to control, and the outlook is not good for species such as the dusky-faced meadow katydid and marsh conehead. To my knowledge the once relatively widespread stripe-faced meadow katydid now is confined to a single site, and the slender conehead, never known from many locations, apparently is gone from the region.

Stripe-faced meadow katydid

Introductions have not been limited to plants. Several species of singing insects also have been imported. Roesel’s katydid is the most common of these in our region. A European predaceous katydid, Roesel’s was introduced to the Montreal, Quebec, area several decades ago and expanded from there. They occur in open habitats with tall herbaceous vegetation throughout the Chicago region. Japanese burrowing crickets are thought to have arrived at the port of Mobile and spread out from there. They are abundant as far north as Indianapolis, and common in Rensselaer in the southern part of our region. With scattered new appearances each year occurring as far north as DuPage County in Illinois, so far, I expect them to become widespread and abundant here. The tropical house cricket represents the possibility of other, short-term introductions that are unlikely to persist in our climate.

Roesel’s katydid

Literature Review: Ice Ages and Climate

by Carl Strang

Today’s literature focus is on two studies from last year that increased our understanding of ice age dynamics and how our changes to the atmosphere may alter them.

Kokechik Bay, Alaska, late winter

Kokechik Bay, Alaska, late winter

Ballantyne, Ashley P., et al. 2013. The amplification of Arctic terrestrial surface temperatures by reduced sea-ice extent during the Pliocene. Palaeogeography, Palaeoclimatology, Palaeoecology, DOI: 10.1016/j.palaeo.2013.05.002  As described in a ScienceDaily article. Recent measures of carbon dioxide in the atmosphere have brought current levels into the range of the Pliocene, which was 3.5-9 degrees F warmer than today. A modeling study indicates that the difference may have been that the Arctic Ocean then was open year-round, a condition toward which we are trending now.

Kerr, Richard A. 2013. How to make a great ice age, again and again and again. Science 341:599. News article describing a study published in Nature that reports an advance in understanding the continental glacier cycle. That cycle corresponds to the 100,000-year stretching and shrinking of the Earth’s orbit around the sun, but that’s too weak to account for ice building and declining. The group led by Ayako Abe-Ouchi modeled in the 23,000-year wobble in the Earth’s spin axis, plus global climate modeling and data on northern ice sheets, which involve changing carbon dioxide levels and the mass of the ice. Simulated ice sheets expanded and contracted in close to the actual pattern. Ice gradually builds over the 100,000-year cycle, but then the 23,000-year cycle corresponds to the warming phase of the longer one, adding summer warmth. By then, crustal depression by the ice mass means that the ice is at a lower, warmer altitude (1 km of depression), and the glacier rapidly melts.

Literature Review: The Cenozoic Era

by Carl Strang

This week we look at some recent studies of the time between the Mesozoic Era and the present day. In recent years there has been much interest in the dynamics of climate change across the ages of the Earth.

A huge amount of carbon today is sequestered in the permafrost soils of the North.

A huge amount of carbon today is sequestered in the permafrost soils of the North.

Robert M. DeConto, et al. Past extreme warming events linked to massive carbon release from thawing permafrost. Nature, 2012; 484 (7392): 87 DOI: 10.1038/nature10929 They combined modeling with the Earth’s orbital dynamics to show the likelihood that in the Paleocene, when the Earth’s orbit became more eccentric and tilt became greater, this resulted in thawing and decomposition of permafrost, releasing huge amounts of carbon dioxide and resulting in a positive feedback loop that produced the Paleocene-Eocene Thermal Maximum.

Pitcher plants, Big Thicket. The following study traces their origin.

Pitcher plants, Big Thicket. The following study traces their origin.

Ellison AM, et al. (2012) Phylogeny and Biogeography of the Carnivorous Plant Family Sarraceniaceae. PLoS ONE 7(6): e39291. doi:10.1371/journal.pone.0039291 They studied nuclear, mitochondrial and plasmid genes to sort out relationships and evolutionary history of the pitcher plants. They conclude that the family appeared in South America 44-53mya (million years ago, Eocene), and by the end of the Eocene was widespread in North and South America.

G. Grellet-Tinner, et al. (2012) The First Occurrence in the Fossil Record of an Aquatic Avian Twig-Nest with Phoenicopteriformes Eggs: Evolutionary Implications. PLoS ONE 7(10): e46972. doi:10.1371/journal.pone.0046972 They found fossils of a basal flamingo in association with eggshells and a floating nest that are like those of modern grebes, in an early Miocene shallow-lake wetland with high evaporation, in Spain. Though they agree that there was an earlier split between the grebes and the flamingos, they mention that fossil flamingos are known from the Oligocene, grebes from the Miocene. Apparently the bones are insufficient to provide much of an understanding of this early flamingo’s appearance.

Zhang Z, Feduccia A, James HF (2012) A Late Miocene Accipitrid (Aves: Accipitriformes) from Nebraska and Its Implications for the Divergence of Old World Vultures. PLoS ONE 7(11): e48842. doi:10.1371/journal.pone.0048842 They describe a fossil bird from Nebraska that links New World hawks and eagles to the Gypaetinae, one of the subfamilies of Old World vultures. This places the timing of that group’s origin in the Miocene, and supports its evolutionary separation from the other Old World vulture subfamily, the Aegypiinae.

Elderfield, H., et al. 2012. Evolution of ocean temperature and ice volume through the mid-Pleistocene climate transition. Science 337:704-709. (Comment by Peter U. Clark on pp. 656-658 in the same issue). They sorted through various isotopic proxies in marine sediments from New Zealand, and found an association between the mysterious change in ice age periodicity around 900,000 years ago (from cycles of 41,000 years to the more recent cycles of 100,000 years, a change not connected to the Earth orbit fluctuations now known to be the underlying cause of ice age cycling generally) and an increase in the volume of ice around Antarctica. They suggest that “an anomalously low Southern Hemisphere summer insolation” failed to melt the Antarctic ice during one interglacial period, and that the ice added during the following ice age was enough to produce the observed period change. The sea level drop during ice ages changed from 70 meters to 120 meters as a result. Their data also argue against a gradual cooling, from changes in atmospheric carbon dioxide, as the primary driver of the periodicity change.

Jeremy D. Shakun, et al. Global warming preceded by increasing carbon dioxide concentrations during the last deglaciation. Nature, 2012; 484 (7392): 49 DOI: 10.1038/nature10915 From an article in ScienceDaily: “Here is what the researchers think happened.

“Small changes in Earth’s orbit around the sun affected the amount of sunlight striking the northern hemisphere, melting ice sheets that covered Canada and Europe. That fresh water flowed off of the continent into the Atlantic Ocean, where it formed a lid over the sinking end of the Atlantic Meridional Overturning Circulation — a part of a global network of currents that brings warm water up from the tropics and today keeps Europe temperate despite its high latitudes.

“The ocean circulation warms the northern hemisphere at the expense of the south, the researchers say, but when the fresh water draining off the continent at the end of the last Ice Age entered the North Atlantic, it essentially put the brakes on the current and disrupted the delivery of heat to the northern latitudes.

“ʻWhen the heat transport stops, it cools the north and heat builds up in the Southern Hemisphere,ʼ Shakun said. ʻThe Antarctic would have warmed rapidly, much faster than the time it takes to get CO2 out of the deep sea, where it was likely stored.

“ʻThe warming of the Southern Ocean may have shifted the winds as well as melted sea ice, and eventually drawn the CO2 out of the deep water, and released it into the atmosphere,ʼ Shakun said. ʻThat, in turn, would have amplified warming on a global scale.ʼ”

The study was a global review of the timing of temperature and atmospheric carbon dioxide changes at the end of the last period of continental glaciation.

Literature Review: Mesozoic Era

by Carl Strang

This week’s scientific literature focus is on recent studies of the Mesozoic Era, the “age of dinosaurs.”

Sun,Yadong, et al. 2012. Lethally Hot Temperatures During the Early Triassic Greenhouse. Science 338: 366-370. They used oxygen isotope ratios in conodont (small eel-like fishes) teeth to measure temperatures, and found that for 5 million years into the Triassic, temperatures were too high to permit terrestrial or marine vertebrate life in the tropics (50-60C = 122-140F on land, 40C = 104F ocean surface waters). Some ferns and shrubs could withstand this but their growth was limited, and there were no tropical forests. Without plants to sequester carbon dioxide, the runaway global warming resulted. Until this study it was thought that ocean temperatures could not exceed 30C.

Artist’s rendition of a prosauropod, subject of the following study, from an exhibit at the Field Museum of Natural History.

Artist’s rendition of a prosauropod, subject of the following study, from an exhibit at the Field Museum of Natural History.

Robert R. Reisz, David C. Evans, Eric M. Roberts, Hans-Dieter Sues, Adam M. Yates. Oldest known dinosaurian nesting site and reproductive biology of the Early Jurassic sauropodomorph Massospondylus. Proceedings of the National Academy of Sciences, 2012; DOI: 10.1073/pnas.1109385109 The grouped nests, eggs showing embryo details, and the presence of tracks of young twice the size of the embryos, points to a prolonged attachment to the nest sites. The eggs in the nests appear to have been carefully arranged by the adults. All of this points to prolonged parental care in a relatively early (prosauropod) dinosaur.

Balter, Michael. 2012. Flying dinos and baby birds offer new clues about how avians took wing. Science 338:591-592. This news review article discusses the origin of flight in dinosaurs and birds, focusing on Microraptor, a crow-sized Chinese dromaeosaurid. There has been some debate about this and other “4-winged” species which had wing-like rows of quill feathers on their legs as well as their forelimbs. An early idea was that the leg structures added gliding planes to those of the wings. Others argue that they would have served as rudders for quick turns, aided by stabilization from the animal’s long tail. Another idea with traction among many in this field is the “wing-assisted incline running” hypothesis, according to which the wings would have helped such animals quickly to climb trees to escape predators. Some recent research has focused on immature chukars, birds which have a number of features in common with the feathered dinosaurs but which are lost during development as they are transformed into the adult birds’ structures. The immature chukars cannot fly, but they are able to perform wing-assisted incline running. They lose much of this ability if their wing feathers are clipped.

Zelenitsky, Darla K., et al. 2012. Feathered non-avian dinosaurs from North America provide insight into wing origins. Science 338:510-514. The first fossil dinosaurs with feathers found in North America are ornithomimids from the Upper Cretaceous in which the young have only downy body coverings but adults add wings. These animals could not fly, so the quills were involved in adult activity such as courtship or brooding of young.

Achim G. Reisdorf, Michael Wuttke. Re-evaluating Moodie’s Opisthotonic-Posture Hypothesis in Fossil Vertebrates Part I: Reptiles—the taphonomy of the bipedal dinosaurs Compsognathus longipes and Juravenator starki from the Solnhofen Archipelago (Jurassic, Germany). Palaeobiodiversity and Palaeoenvironments, 2012; DOI: 10.1007/s12549-011-0068-y As described in a ScienceDaily article. Dinosaurs and relatives, including Archaeopteryx, often are found fossilized with the neck dramatically bent backward over the back. This had been thought to be a sort of death throes pattern, but Reisdorf and Wittke did experiments with chickens that revealed this to be a process of decomposition. A relatively decay-resistant ligament, the Ligamentum elasticum, is “pre-loaded” as a spring-like support along the top of the vertebral column in dinosaurs with long necks and tails. As decomposition proceeds in water (usually fossilized animals are preserved in aquatic sediments), the opposing muscles and connective tissues on the front of the neck break down first, so that the Ligamentum elasticum gradually pulls the neck back into the observed posture.

Gregory P. Wilson, Alistair R. Evans, Ian J. Corfe, Peter D. Smits, Mikael Fortelius, Jukka Jernvall. Adaptive radiation of multituberculate mammals before the extinction of dinosaurs. Nature, 2012; DOI: 10.1038/nature10880 From ScienceDaily article. They did a comparative study of multituberculates, an early mammal group that arose by 170mya (million years ago) and went extinct around 34mya. Their appearance as mouse-sized species preceded the diversification of angiosperms, but their own diversity increased after that happened, so that they ranged as large as beavers. There was a concurrent increase in tooth complexity, showing many facets facing in various directions especially in the molars, a change associated with a vegetarian diet (though many species had teeth more suggestive of an insect diet). Dinosaurs never matched this, even herbivorous ones either developing batteries of relatively flat-topped grinders, or swallowing plant material whole and using gastric mills. The small body size and dietary capabilities apparently contributed to multituberculate survival when the dinosaurs became extinct.

A model of a hadrosaur, Brookfield Zoo. These possibly hold the all-time record for tooth tissue complexity.

A model of a hadrosaur, Brookfield Zoo. These possibly hold the all-time record for tooth tissue complexity.

G. M. Erickson, Gregory M., et al. 2012. Complex dental structure and wear biomechanics in hadrosaurid dinosaurs. Science 338: 98-101. They examined the microstructure and mechanical properties of hadrosaur teeth, and found that these were more complex than molars of mammalian herbivores (with 6 rather than 4 tissue types), and were more effective as grinders of tough plant tissues. This helps explain why they became so successful, diverse and abundant in their time.

Gates TA, Prieto-Márquez A, Zanno LE (2012) Mountain Building Triggered Late Cretaceous North American Megaherbivore Dinosaur Radiation. PLoS ONE 7(8): e42135. doi:10.1371/journal.pone.0042135 They tie the unusual diversification of hadrosaurs and ceratopsians in western North America to the timing of its isolation by the inland seaway and the simultaneous development of 2 mountain ranges within it. This produced geographic isolation of populations over a large north-to-south gradient. They conclude that this was a special case, and it should not be assumed that such species diversity was characteristic of that time globally.

Stephen L. Brusatte, Richard J. Butler, Albert Prieto-Márquez, Mark A. Norell. Dinosaur morphological diversity and the end-Cretaceous extinction. Nature Communications, 2012; 3: 804 DOI: 10.1038/ncomms1815 As described in a ScienceDaily article. They reviewed morphological variation in the late Cretaceous in different parts of the world, working out of the premise that little variation may signal species headed toward extinction, while much variation may represent vigor and the potential for division into more species. Some groups in some parts of the world were found to represent each of these alternatives. Western North American dinosaurs after the incursion of the inland sea showed signs of deterioration. This may be tied to their more limited geographic area, the sea taking some land and western mountains further limiting the range. Large herbivores (hadrosaurs and ceratopsids) for the most part were declining, though carnivores and mid-sized herbivores (ankylosaurs, pachycephalosaurs) as well as sauropods were not. Asian hadrosaurs showed the opposite pattern, however.

Kerr, Richard A. 2012. Before the dinosaurs’ demise, a clambake extinction? Science 337:1280. News article describing a study of relatively thick strata from Antarctica that allow separation of effects of the Deccan Traps volcanic eruptions (comparable to the Siberian Traps associated with the end-Permian extinctions) from the impact that is generally regarded as ending the Cretaceous. The research group led by Thomas Tobin found results indicating that the Deccan Traps eruptions began 200,000 years before the impact, and this correlated with a warming of water in the bottom of the ocean and extinctions of clams and snails. Free-swimming ammonites were not affected by this, however.

Literature Review: The Early Earth

by Carl Strang

This week’s literature review begins a 4-week series that updates the material I shared in the Prehistoric Life winter series a couple years ago. The studies highlighted below looked at the time period from the Earth’s origin through the Paleozoic Era.

M. Touboul, I. S. Puchtel, R. J. Walker. 182W Evidence for Long-Term Preservation of Early Mantle Differentiation Products. Science, 2012; DOI: 10.1126/science.1216351

As described in a ScienceDaily article. They found evidence, in the form of a high portion of a particular tungsten isotope in some volcanic rocks, that a portion of the Earth’s previously formed mantle survived the Theia impact intact, implying that the Earth did not completely melt during or after that event. (This was the collision that in one dramatic moment created our moon and tilted the Earth on its axis, so that the seasons and the tides, so important to the diversity of life on Earth, became possible.)


Alexander, C.M.O’D., et al. 2012. The provenances of asteroids, and their contributions to the volatile inventories of the terrestrial planets. Science 337:721-723.

They looked at isotopic ratios of elements in asteroids vs. comets, and concluded that most of the water, nitrogen and carbon in the Earth and other inner planets came from bombardment by meteorites that originated as asteroids, rather than from comets.


M. R. Smith. Mouthparts of the Burgess Shale fossils Odontogriphus and Wiwaxia: implications for the ancestral molluscan radula. Proceedings of the Royal Society B: Biological Sciences, 2012; DOI: 10.1098/rspb.2012.1577

As reported in a ScienceDaily article. Graduate student Martin Smith examined fossils with a new form of electron microscopy, and found mouthparts that are clear predecessors of the molluscan radula. That early, tonguelike feature likely was used for scooping food from muddy sea floors rather than for scraping as radulas do today.

The following study points to green algae as the ancestors of all the land plants.

The following study points to green algae as the ancestors of all the land plants.

Timme RE, Bachvaroff TR, Delwiche CF (2012) Broad Phylogenomic Sampling and the Sister Lineage of Land Plants. PLoS ONE 7(1): e29696. doi:10.1371/journal.pone.0029696

They constructed a comparison of 160 nuclear genes to identify which group of algae contains the ancestral species which invaded land and became the founding species from which all land plants evolved. Their results point to the Zygnematales, the pond scum algae group.


Timothy M. Lenton, Michael Crouch, Martin Johnson, Nuno Pires & Liam Dolan. First plants cooled the Ordovician. Nature Geoscience, 2012 DOI: 10.1038/ngeo1390

From ScienceDaily. Their experiments on the chemical weathering of rocks by mosses suggest that the invasion of land plants released minerals that took carbon dioxide out of the atmosphere, and also stimulated oceanic blooms that further sequestered carbon as the resulting organisms were buried, in addition to the carbon sequestered by the land plants themselves. The authors estimate that the resulting carbon dioxide depletion was sufficient to trigger the end-Ordovician ice ages and associated extinctions. They also point out that plants continue to have a cooling effect on the atmosphere, though in the present day this is overwhelmed by technological injection of carbon dioxide.

Literature Review: Ornithology

by Carl Strang

Birds are the focus of this week’s literature feature.

The superb fairy-wrens of Australia have revealed yet another amazing wrinkle in their biology.

The superb fairy-wrens of Australia have revealed yet another amazing wrinkle in their biology.

Diane Colombelli-Négrel, Mark E. Hauber, Jeremy Robertson, Frank J. Sulloway, Herbert Hoi, Matteo Griggio, Sonia Kleindorfer. Embryonic Learning of Vocal Passwords in Superb Fairy-Wrens Reveals Intruder Cuckoo Nestlings. Current Biology, 2012; DOI: 10.1016/j.cub.2012.09.025

As described in a ScienceDaily article. They noticed that female superb fairy-wrens sing to their eggs, and they later demonstrated experimentally that the mothers were teaching their future nestlings a particular note, described by the authors as a password, that the nestlings would need to include in their begging calls to be fed. This note varies from nest to nest, and if the parents do not hear it they abandon. This is a novel way of dealing with nest parasites, in this case cuckoos, whose eggs and nestlings do not have the programming to learn and repeat the password.

Katzner, Todd, et al. 2012. Status, biology, and conservation priorities for North America’s eastern golden eagle (Aquila chrysaetos) population. Auk 129:168-176.

The eastern population estimate is 1000-2500 (east of the Mississippi River; western population 21,000-35,000). The species generally appears to be declining, though the eastern population has increased since the ban on DDT. Lead poisoning and incidental damage by leg-hold traps set for mammals are the biggest threats to eastern eagles. They are most abundant in Quebec, fewer in Ontario and Labrador as breeders. There has been no nesting in the eastern U.S. since the late 1990’s, the last ones in Maine and New York state. In Canada, nest sites are away from forested areas, mainly “at the interface of tundra, boreal forest, and wet meadows.” An estimated 15-25% migrate through the Great Lakes region. Wisconsin and Iowa host at least 70 birds in winter; the wintering status in Illinois is given as “unknown.”

The next study supports the idea that birds are more diverse in the tropical forests because of that biome’s greater age.

The next study supports the idea that birds are more diverse in the tropical forests because of that biome’s greater age.

W. Jetz, Thomas, G. H., Joy, J.B., Hartmann, K. & A.O. Mooers. The global diversity of birds in space and time. Nature, October 31, 2012.

As described in a ScienceDaily article. They did a combined fossil and DNA study of 10,000 bird species, and found unusual evolutionary diversification has been happening over the past 50 million years. Furthermore, the rate of new species appearance has not leveled off, but rather continued or even increased, in contrast to the usual pattern in which a foundational species diversifies but then a plateau is reached when available niches are filled. They attribute this difference to birds’ mobility, the opening of new habitats, and certain adaptable avian traits. Furthermore, there is no difference between speciation rates in the tropics and more polar regions, supporting a longer continuous history of tropical environments as being responsible for greater tropical diversity of birds (species accumulating, but extinction less rapid).

Stanley CQ, MacPherson M, Fraser KC, McKinnon EA, Stutchbury BJM (2012) Repeat Tracking of Individual Songbirds Reveals Consistent Migration Timing but Flexibility in Route. PLoS ONE 7(7): e40688. doi:10.1371/journal.pone.0040688

They followed individual wood thrushes over several migrations, and found that individuals showed little variation in spring migration departure date, and arrival date on territory, but much more flexibility in migration route and in fall departure date.

Brommer JE, Lehikoinen A, Valkama J (2012) The Breeding Ranges of Central European and Arctic Bird Species Move Poleward. PLoS ONE 7(9): e43648. doi:10.1371/journal.pone.0043648

They compared breeding bird atlases conducted in Finland, finding that there have been shifts northward in the centers of ranges for both northern and central European species. The shifts are happening slowly enough that surveys need to be taken decades apart. Northward advance of the northern edges of ranges is happening more quickly than extinctions at southern edges. The latter consideration is needed if range shifts are to be attributed to global climate change.

Singing Insects Range Extensions

by Carl Strang

My other presentation at Saturday’s Wild Things conference reviewed the range extensions by 8 species of singing insects that have turned up in our region in recent years. I ran through them in the chronological order of their discovery, and then offered some general points.

Broad-winged tree cricket (Oecanthus latipennis)


Map from the Singing Insects of North America website (SINA), 2012. The record in DuPage County resulted from this study, and was added in 2006. Prior to that the species was not supposed to occur in the Chicago region.

Map from the Singing Insects of North America website (SINA), 2012. The record in DuPage County resulted from this study, and was added in 2006. Prior to that the species was not supposed to occur in the Chicago region.

Original range sources: Hebard 1934  (“Northern limits of distribution are Hilliary and Quincy”), McCafferty & Stein 1976 described it as a central and southern species in Indiana, with Tippecanoe County the northern extent. I found them in DuPage County in 2006, and subsequently learned they are abundant throughout the county. They also have reached the junction of the Wisconsin and Mississippi Rivers in Wisconsin.

Jumping bush cricket (Orocharis saltator)


Jumping bush cricket SINA map, 2012. The added red line indicates the northern range limit as of 1969, when Tom Walker reviewed the genus.

Jumping bush cricket SINA map, 2012. The added red line indicates the northern range limit as of 1969, when Tom Walker reviewed the genus.

Original range sources: Hebard 1934 (Shawneetown northern limit in Illinois; “should however be found throughout southern Illinois as it is known as far north as central Indiana”). McCafferty & Stein 1976 (“known only from the southern two-thirds of the state” with Tippecanoe County given as the northern limit). They are rapidly expanding in DuPage County, abundant in the southern half and spreading into the northern half with new northern limits found annually. I also have heard them at Indiana Dunes State Park.

Roesel’s katydid (Metrioptera roesellii)

Roesel's s-wing female Purdue b

Roesel’s katydid SINA map, 2012. Prior to work by Scott Namestnik and me, the range was thought to end in northeastern Ohio, with a small disjunct area in northeast Illinois. The red dots indicate our added findings in 2012.

Roesel’s katydid SINA map, 2012. Prior to work by Scott Namestnik and me, the range was thought to end in northeastern Ohio, with a small disjunct area in northeast Illinois. The red dots indicate our added findings in 2012.

Original range sources: Roesel’s katydid is a European species that in North America first was found in two suburbs of Montreal, Quebec (Urquhart and Beaudry 1953, Beaudry 1955), and is thought to have been introduced between 1945 and 1951. Vickery (1965), who summarized this history, reported that the species had spread into New York state and Vermont by 1965, and that the long-winged variants that originally had dominated the Montreal population were diminishing in favor of the short-winged forms typical of the European continent. The Montreal population apparently was by then limited by an indigenous parasitic nematode. Roesel’s reached Ithaca, NY, by 1965 (G.K. Morris, as reported by Shapiro 1995), and Long Island by 1990 (Shapiro 1995). Short-winged forms were dominating the St. John, New Brunswick, population by 2008 (McAlpine 2009), and so had arrived some unknown number of years earlier. Nickle (1984) reported finding them in Pennsylvania by the early 1980’s. Roesel’s katydids were collected in two northeastern Illinois counties in the late 1990’s (Eades and Otte, no date). I found them in north central Indiana in 2007, and subsequently Scott Namestnik and I have found them throughout northern Indiana (as far south as Indianapolis) northeast Illinois, and last year the Lower Peninsula of Michigan. Others have added Ohio, Wisconsin and eastern Iowa.

Round-tipped conehead (N. retusus)

Roesel’s katydid SINA map, 2012. Prior to work by Scott Namestnik and me, the range was thought to end in northeastern Ohio, with a small disjunct area in northeast Illinois. The red dots indicate our added findings in 2012.


Round-tipped conehead SINA map, 2012. The added red line indicates the northern extent of the range in Illinois in 1934 and in Indiana in 1976.

Round-tipped conehead SINA map, 2012. The added red line indicates the northern extent of the range in Illinois in 1934 and in Indiana in 1976.

Original range sources: Hebard 1934 (“Urbana is a northern limital point”), and McCafferty and Stein (1976) had none north of Indianapolis, but they are so common in northwest Indiana and northeast Illinois now that this is a well advanced range expansion in the intervening decades. I also heard a single singing individual in a meadow at Wyalusing State Park in Wisconsin in 2007.

Handsome trig (Phyllopalpus pulchellus)

Handsome trig 2b

Handsome trig SINA map, 2012. The northern dot at St. Joseph County, Indiana, is the result of Scott Namestnik’s work.

Handsome trig SINA map, 2012. The northern dot at St. Joseph County, Indiana, is the result of Scott Namestnik’s work.

Original range sources: Hebard 1934 (northern limits given as Marion County in Indiana and Monticello in Illinois; “confined to southern and central Illinois”). McCafferty & Stein 1976 indicated a northern extent in Tippecanoe County. In 2009 Scott Namestnik was posting photos of them from St. Joseph County.

Swamp cicada (Tibicen tibicen)

Swamp cicada 4AU 4b

Original range sources: This species was mentioned by Alexander, Pace and Otte in their (1972) Michigan singing insects paper, but they expressed doubt that it was a breeding species in the state. However, a later paper (Marshall, Cooley, Alexander and Moore 1996) reported finding it in extreme southern MI (intensive searching found it only in the southern portions only of the southern tier of counties. They were not willing to say whether this represented a range extension or the species being missed earlier). I first found it in Marshall County, Indiana, and DuPage County, Illinois, in 2010, but suspected I had heard it earlier. They are scattered across the southern half of DuPage.

Slightly musical conehead (N. exiliscanorus)

Slightly musical Max Wet b

Slightly musical conehead SINA map. This does not yet reflect our finding them in Porter and Marshall Counties, Indiana, in 2012.

Slightly musical conehead SINA map. This does not yet reflect our finding them in Porter and Marshall Counties, Indiana, in 2012.

Original range sources: Hebard 1934 (northern limits indicated as Tower Hill in south central Illinois, and New Harmony in Indiana). McCafferty & Stein 1976 (“In Indiana it is known only from heavy thickets and grasses along the Ohio River”). Gideon Ney, Nathan Harness and I, seeking slender coneheads, found this species at the Indiana Dunes National Lakeshore in 2012, and I found it in Marshall County as well.

Marsh conehead (N. palustris)

Slightly musical conehead SINA map. This does not yet reflect our finding them in Porter and Marshall Counties, Indiana, in 2012.


Marsh conehead SINA map. This does not yet reflect our finding them in Porter County, Indiana, in 2012.

Marsh conehead SINA map. This does not yet reflect our finding them in Porter County, Indiana, in 2012.

Original range sources: Hebard 1934 (“Lawrenceville and Carbondale are northern and western limits respectively for palustris…It is probably confined to the southern portions of Indiana and Illinois.”). McCafferty & Stein 1976 reported Tippecanoe County as the northern known extent. Ney, Harness and I found this species to be common at Indiana Dunes National Lakeshore and present in the state park.

General Points

Most of these range extensions are from south to north. Exceptions are Roesel’s katydid (east to west) and the broad-winged tree cricket (spreading south as well, according to SINA coordinator Tom Walker).

I do not know whether any other of these species likewise are spreading south or in other directions.

Some of these are clear range expansions, as they are species which were well known at the time of earlier studies, and now have become abundant beyond the range as then drawn: broad-winged tree cricket, jumping bush cricket, Roesel’s katydid, and round-tipped conehead.

The others have a spottier distribution, or may not have been as well known then, and so might have been missed by earlier researchers: handsome trig, swamp cicada, slightly musical conehead, and marsh conehead.

As for the possible connection between these range extensions and climate change, Gonzalez (2012) mentioned a calculation, based on work in Gonzalez et al. (2010), indicating that the region’s climate has undergone a temperature change equivalent to a southward shift in latitude of 100km in the 20th century. This is consistent with the magnitude of many of these observed range changes.

Literature Review: Climate Change and Range Shifts

by Carl Strang

Global climate change, like evolution, is a matter of debate among politicians, but not among scientists. At this point it’s a routine matter of measurement and documentation. One example from last year was a study published in Science (Chen, I-Ching, et al. 2011. Rapid range shifts of species associated with high levels of climate warming. Science 333:1024-1026).

They reviewed a variety of terrestrial organisms, including invertebrates, vertebrates and plants, and found that species distributions “have recently shifted to higher elevations at a median rate of 11.0 meters per decade, and to higher latitudes at a median rate of 16.9 kilometers per decade…The distances moved by species are greatest in studies showing the highest levels of warming,…However, individual species vary greatly in their rates of change.” While their data show most species shifting poleward, a few shifted in the opposite direction.

The round-tipped conehead is one of several singing insect species I have been finding with significant northward range shifts in the past 70 years.

The Chen et al. paper will allow me to compare their measurements with rates of expansion I can estimate from the literature and my observations of at least 4 species of crickets, katydids and cicadas. I’m pretty sure the movements of these species will prove to be consistent with their findings.

Lessons from Travels: Clouds from Above

by Carl Strang

One of the delights of air travel is the opportunity to view clouds from above. To be sure, there is much beauty to be enjoyed from the play of light on clouds we see from the ground.

Winter sunset

The new perspective from a jet liner adds a different perspective. We’ll follow the common summer sequence, beginning with simple cumulus.

Cumulus clouds are the common puffs we all know and draw as children.

These are simple enough that they look much the same from above.

The mosaic of the ground provides a visually interesting backdrop.

As a summer day passes, solar energy causes an increase in the rising air columns and their moisture content. The cumulus clouds swell as that moisture hits cooler air above and condenses.

They become bigger and more complex in shape.

Now there is more to be seen from the air, as well.

The clouds seem to form a landscape of rounded mountains and valleys.

If conditions are extreme enough, the clouds coalesce, and build high into the atmosphere.

Those who know something of the process, and see this, begin to assess where shelter is to be found.

A full appreciation can be gained from the higher-altitude perspective.

The anvil shape of a cumulonimbus, the cloud of the thunderstorm.

A final lesson comes when one notices that at a typical cruising altitude of only 5 miles, nearly all the clouds are below.  The realization begins to sink in that the breathable, active atmosphere is thin indeed, the barest skin’s thickness when compared to the size of the Earth as a whole. Yes, it is a small enough volume easily to be changed by the actions of billions of technologically leveraged human beings.

Literature Review: Global Climate Change

by Carl Strang

This blog focuses on studies of local natural history, but there is no question that the future of any ongoing story is subject to whatever form climate change may take. Today I share notes from my annual literature review that are particularly relevant to this subject.

McCarthy, James J. 2009. Reflections on: our planet and its life, origins, and futures. Science 326:1646-1655. This is the AAAS presidential address. In it he cites an impressive model and data set showing a tight correlation of global monthly mean temperatures with a combination of 4 factors, each of which contributes significantly to the variation. They are the El Niño-Southern Oscillation (especially responsible for unusually warm or cold years), volcanic aerosols (generally constant but in occasional year-long bouts of low levels producing global temperature dips), solar irradiance (rising and falling on a roughly decade-long cycle) and anthropogenic effects (mainly greenhouse gas emissions, producing an overall strong upward trend over the past 3 decades). He also says that “Demographic studies suggest that because of declining birthrates across much of the developing world, a future doubling of today’s population of 6.8 billion is unlikely. Most projections point to a leveling off of human population at 9 to 11 billion within the next two to three generations.”

Ditlevsen, P. D., and S. J. Johnsen. Tipping points: Early warning and wishful thinking. Geophys. Res. Lett., DOI: 10.1029/2010GL044486

Their studies of sudden episodes of drastic climate change during the ice ages casts a new light on climate change concerns. Earlier research had found that on several occasions, temperature shifts of 10-15 degrees occurred in only one to a few decades during the glacial times. Such shifts between relatively stable climate states then persisted sometimes for hundreds of years. Understanding them requires the inclusion of chaos theory, which makes them essentially impossible to predict given current knowledge. While the authors point out that this is a study of past events rather than the current situation, they also mention that carbon dioxide levels have risen to match those of much warmer global conditions 15 million years ago, and this might influence the system to jump into a different stable state over a very short span of years.

Kitcher, Philip. 2010. The climate change debates. Science 328:1230-1234. This extensive review of a number of recent books on climate change does a good job of bringing out how the debate has taken place, and the various roles taken by authoritative scientists, the media, politicians, business interests, the public, and “obfuscators,” scientists from other fields who have claimed an authority they don’t possess.

Smithsonian Institution (2010, February 2). Forests are growing faster, ecologists discover; Climate change appears to be driving accelerated growth. ScienceDaily. Retrieved February 3, 2010, from­ /releases/2010/02/100201171641.htm

“For more than 20 years forest ecologist Geoffrey Parker has tracked the growth of 55 stands of mixed hardwood forest plots in Maryland. The plots range in size, and some are as large as 2 acres. Parker’s research is based at the Smithsonian Environmental Research Center, 26 miles east of the nation’s capital.

“Parker’s tree censuses have revealed that the forest is packing on weight at a much faster rate than expected. He and Smithsonian Tropical Research Institute postdoctoral fellow Sean McMahon discovered that, on average, the forest is growing an additional 2 tons per acre annually. That is the equivalent of a tree with a diameter of 2 feet sprouting up over a year…

“During the past 22 years CO2 levels at SERC have risen 12%, the mean temperature has increased by nearly three-tenths of a degree and the growing season has lengthened by 7.8 days. The trees now have more CO2 and an extra week to put on weight. Parker and McMahon suggest that a combination of these three factors has caused the forest’s accelerated biomass gain.”

Stone, Richard. 2010. Home, home outside the range? Science 329:1592-1594. This news-review article describes the debate over whether people should use assisted colonization (the deliberate northward displacement of populations) to help species survive climate change. Opponents cite examples of the problems that arise with introductions of nonnative species. Proponents point to successes that have been achieved with relatively small northward shifts. Conditions under which assisted colonization is called for are being debated and developed.

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