Aquatic Mammal Scats

by Carl Strang

Soon after I started checking the amphibian traps I set in the marshes at Mayslake Forest Preserve I noticed signs that the traps were being used.

Mammal scats. The trap’s quarter-inch mesh gives a scale.

Other scats on nearby logs were drier, but about the same size.

They are composed of vegetable matter.

These are muskrat scats. Muskrats leave them on exposed surfaces just above the water, indicators to other muskrats that this marsh is occupied. I have known muskrats to construct rafts of cut plants when there were no readily available platforms.  This little marsh is showing itself to be home to quite a diversity of animal life.

Meanwhile, in the narrow stream nearby, I have noticed that a prominent rock likewise has been accumulating a mammal’s calling cards.

These are smaller in diameter than the muskrat’s scats, darker in color and in linear arrays.

A close look reveals what appear to be tiny fish bones.

The bones by themselves don’t rule out muskrat, but this is a narrow swift stream, and repeat visits here by a muskrat are unlikely. Also, other structural features in these droppings point to a different species.

These scats in fact reveal that the mink I tracked through the winter continues to pass this way frequently. I find it interesting that two aquatic mammals in different orders use similar behaviors to communicate their presence.

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Ducks at Mayslake

by Carl Strang

This has been a good spring for migrant ducks at Mayslake Forest Preserve. Two new species have added themselves to the preserve’s bird list, a female goldeneye on May’s Lake a couple weeks ago, and a pair of gadwalls last week.

The male gadwall’s black hind end is unmistakable.

Note how the female gadwall’s head and bill shape match those of the male gadwall and contrast with the female mallard in the foreground.

More expected but no less enjoyable have been a few wood ducks on May’s Lake.

As in other ducks, the female wood duck’s plumage provides much better camouflage than does the male’s.

As of yesterday, the bufflehead pair I reported last week still was hanging out in the stream corridor marsh after 6 days.  I have tried to catch a glimpse of what they are eating, but no luck so far. Do they swallow while submerged?

Another Year’s Squirrel Data

by Carl Strang

Fox and gray squirrels are familiar animals in northeast Illinois. They are easy to tell apart. Gray squirrels have pale gray belly fur, and their tails are mainly gray toned.

Gray squirrels also are smaller than fox squirrels.

Fox squirrels have reddish brown fur beneath, and their tails are reddish and black.

The orange pigment also occurs in a fox squirrel’s bones, and the lenses of its eyes. Fox squirrels have built-in sunglasses.

As I mentioned a year ago, fox and gray squirrels are adapted to different habitats. Gray squirrels are forest animals, while fox squirrels live in the more open savannas. Both species occur at Mayslake Forest Preserve, where the savannas are high in quality but the forests are poor. By “poor” I mean they have lots of buckthorn, very little diversity of herbaceous plants, and the trees are mainly young members of weedy (fast-growing, relatively short lived) species.

I have been keeping records of where I see fox and gray squirrels at Mayslake. As there is more savanna than forest habitat there, I expect to see more fox squirrels. To what extent do the two squirrel species stick to their expected habitats? Here are the results of two years’ study. Observations total 853 for fox squirrels, 209 for gray squirrels. As expected, the former species appears to be much more abundant.

If the two species had no preference, i.e. occurred in forest and savanna areas in proportion to those areas’ sizes, I would expect 528 of the 853 fox squirrel observations to be in savanna, 325 in forest. Instead the numbers are 726 and 127, respectively. This shows the expected strong preference for savanna (for what it’s worth, the χ 2 test statistic value is a whopping 194.8).

If gray squirrels were showing no habitat preference, I would expect 129 observations in savanna, 80 in forest. The observed numbers were 160 and 49, respectively. This likewise reveals a preference for the superior savanna habitat (chi-squared = 19.5, also plenty large).

The preference for savanna does not appear to be quite so strong in the gray squirrel, however. Is there a difference between the species? If I base my expectations for gray squirrels on the ratios seen in fox squirrels, I should have seen 178 gray squirrels in savanna, 31 in forest. Again, the observed numbers were 160 and 49. Here the χ 2 = 12.3, large enough to support a difference between the species’ degree of preference. I will continue to monitor these two species, to see if there are any changes over the years.

Prehistoric Life 19

by Carl Strang

This year’s winter series has been a review of the prehistoric life and geologic history of northeast Illinois. Each chapter has summarized current understanding, gleaned from the literature, of what was going on with life on Earth in a particular span of time, what we know about the local landscape, and what we can say about local life. I include some references, particularly to papers published in the journal Science which commonly is available at public libraries. Contact me if you need sources for other items. The Earth is so old that every imaginable environment was here at some point, from ocean depths to mountaintops, from equatorial tropics to tundra, and from wetlands to desert. Today’s chapter concludes the series.

At last we reach the most recent times. This mastodon and its kind lived in our area in the recent past.

Pleistocene Epoch (1.64 million years ago to the present day)

The Pleistocene Epoch (named 1839), literally “most recent,” marks the latest series of continental glacial times. We are in an interglacial interval, regarded as part of the Pleistocene by some, by others named separately the Holocene (1885) or Recent (1833) Epoch.

Life on Earth. This is the time when our human species Homo sapiens evolved, along with the rest of the modern species. Our species originated in Africa around 200,000 years ago as it separated from its earlier hominid precursors, then began to migrate out of Africa around 100,000 years ago, fanning out into Europe, Asia, Polynesia-Australia and ultimately North America. Homo erectus earlier (1.5 million to 770,000 years ago) ranged from Kenya to China (Science 323:1197, 1419). Shaped tools and red ochre use suggest modern-like behavior had begun to appear by 164,000 years ago (Science 318:777). Genetic studies indicate that the Neandertals were a separate species, though they shared with us a gene for speech communication (Science 318:546). Skin color may have diversified in our species much more recently, with pale skins in some races developing only within the past 5300-12,000 years (Science 316:364).

Reconstructed giant ground sloth, Mastodon State Historic Site, Missouri.

There were new arrivals in North America from South America: 2 sloth genera (Nothrotheriops and Eremotherium), opossum, anteaters. And, from Eurasia, mammoths, bison, saiga, musk oxen, and humans. The polar bear evolved away from brown bear ancestors of the southeast Alaska area around 150,000 years ago. Many large birds and mammals became extinct, in many areas (including North America) because of human hunting (Science 300:885; 306:70).

Local landscape. This was a time of ice ages, more than 20 periods of continental glaciation alternating with periods when the glaciers retreated (only 4 of these reached as far as the Mississippi River drainage basin). The dominant theory ties the growth and ebbing of glaciers to regular cycles in the Earth’s orbit, tilt, and precession. Up until 1 million years ago, the glacial cycles were 41,000 years long, corresponding to the cycling of the Earth’s tilt. For the past million years the cycle has become 100,000 years long, for reasons that are unexplained but may be connected to a change in atmospheric carbon dioxide.

Rotten or weathered rock had formed at the surface; most of this was removed by Pleistocene glaciers. Glaciers don’t remove much thickness of bedrock, however, carrying mostly fractured pieces. In the DuPage County area, the glaciers scoured the Silurian dolomite bedrock clean of any sediments, except for the Devonian or Mississippian marine clays in cracks on the upper surface (this is why there are no pre-Pleistocene terrestrial fossils in much of northeast Illinois).

If we could clear the glacial deposits from our bedrock we might see something like this, grooves scratched on the surface by the glacier as it pushed southwest out of the Lake Michigan basin. Rock Point, Ontario.

Dolomite bedrock escarpments such as the one tracing the western and southern boundary of the Lake Michigan basin, and other highlands such as the northern Wisconsin Arch, played a significant role in channeling glacial flow. Lake Michigan started as a south-flowing stream. The sequence and timing of events: the Nebraskan glacial advance 1.8mya (million years ago), then the Aftonian interglacial stage, then the Kansan advance 900-600kya (thousand years ago), then the Yarmouthian interglacial, then the Illinoian advance 400-300kya, then the Sangamon interglacial, then the Wisconsinan glacial advance began 100kya and ended 18kya. Within the Wisconsinan there was an Altonian advance 70-30kya that reached northeast Illinois, a retreat 30-22kya called Farmdalian time, and the largest final advance 22-18kya called the Woodfordian.

A continental glacier was not a single body, but rather several rivers of ice, or lobes, flowing side by side. The Silurian escarpment divided the Lake Michigan lobe from the Green Bay lobe. Kettle Moraine in Wisconsin is a glacial deposit left between those lobes. The Lake Michigan Lobe had to climb (be pushed) several hundred feet to overtop the escarpment and enter northeast Illinois.

As the glacier advanced, the Straits of Mackinac outlet became blocked, and Lake Michigan drained south through the Chicago and Des Plaines Rivers. The Glenwood phase of Glacial Lake Chicago, as it is called, was followed by alternating advances and retreats that blocked and opened the Mackinac Straits and further eroded the Des Plaines valley. Because the weight of the glacier had depressed the crust, for a time after the last glacial retreat the river through the Straits lowered Lake Michigan (in that incarnation called Lake Chippewa) to the point where it was much smaller and occupied only part of its current area. Crustal rebound later raised the northern end of the lake to the point where the current basin filled. When the Upper Peninsula of Michigan, Lake Huron and part of Lake Superior were cleared of retreating glacial ice but other outlets still were blocked, the Des Plaines became the major drainage for all three lakes.

In 2007-2008 Mastodon Camp, a partnership between the Forest Preserve District of DuPage County and the Field Museum of Natural History, gave high school teachers and students an opportunity to participate in a dig. Bits of mastodon bone and tusk, as well as buried black spruce trees and cones, were the main physical product from the site at Pratts Wayne Woods Forest Preserve.

During the latest, Wisconsin glaciation, the permafrost (tundra) zone was 50-120 miles wide beyond the glacial margin, and the mean annual temperature was about 5 degrees C cooler than today. Most of our familiar prairie and forest species were restricted to rather small refuges in the South during the glacial maximum, though oaks and hickories occupied a large part of the southern U.S. Species occurred in unfamiliar combinations, which changed as environmental conditions shifted (i.e., distributed themselves according to individual species tolerances rather than in community clusters of species).

According to recent work with cores from Nelson Lake in Kane County and Brewster Creek in DuPage, our landscape originated 18,000 years ago as the Wisconsin glacier melted away. By 17,000 years ago the glacier locally had shrunk back to the Lake Michigan basin. Open sedge tundra with some spruce trees invaded the zone nearest the glacier (18,000-16,000 years ago), then white spruces filled in to form a recognizable northern coniferous forest until around 15,000 years ago. The climate was dry and windy, piling a layer of loess (silty material) on top of the glacial till and outwash. The wind diminished and the climate became wet around 15,000 years ago because of the collision of warm air from the Gulf with polar air from the glacier north of us. White spruce declined, with black spruce becoming important in low wet areas, and black ash and fir along with a variety of deciduous trees invading the uplands. The glacier retreated to Canada by 13,000 years ago, then advanced in a new cool period as far as northern Wisconsin and the U.P. of Michigan (this may have been a Northern-Hemisphere-only cooling: Science 318:86), and began its final retreat 11,650 years ago. Then alder, birch, jack pine, ironwoods and elms increased locally, and additional trees invaded until a mix of deciduous species, including lots of oaks, was achieved. Beginning around 10,000 years ago there was a drying period, which led to the spread of prairie through our area. The prairie then retreated a little, so that by 6200 years ago our area became a prairie with islands of woodlands.

Local life. After the Wisconsin glacier retreated, first there was tundra, home of woolly mammoths (grazers), musk oxen, caribou, collared lemmings and other animals now extinct or found only in arctic Canada and Alaska. People arrived at this time, hunting with spears (one of the earliest human sites in North America, with butchered mammoth bones dated at 12,500 years ago, has been discovered just north of here near Kenosha; Science 305:590). As the forest filled in the warming landscape, additional mammals included moose, stag moose, scimitar cats, dire wolves, giant beavers, snowshoe hares, Jefferson’s ground sloths and mastodons (unlike mammoths these were browsers which also ate walnuts, spruce cones and other seeds; some species such as Kentucky coffee tree and osage orange are thought to be relatively uncommon today because they have lost mastodons and other large herbivores as seed dispersers). During the time of deciduous forest, local mammals included mountain lion, bobcat, red wolf, elk, white-tailed deer, raccoon, gray fox, porcupine, black bear, flying squirrel and gray squirrel. The prairie and mixed prairie savanna of historical times included today’s familiar animals, along with black bears, badgers, mountain lions, red wolves, elk and bison.

Imagined Paleoindians, Mastodon State Historic Site, Missouri.

Clovis points have been found in DuPage County, indicating that some of those early big animal hunters (known as Paleoindians) were here. The largest animals became extinct, thanks in large part to the Paleoindians’ killing them faster than they could reproduce (Science 326: 1100). Subsequent human cultures wandered less, and shifted to more of a hunting-gathering economy in the several thousands of years of the Archaic Period. Thrust spears and spear-throwers did not give way to bow and arrow in North America until later, during the Woodland Period that began with early signs of agriculture about 2000 years ago. Agriculture did not become an important part of the local economy until the most recent 1500-1000 years. The Woodland people were even more sedentary than Archaic people, and used pottery. Mississippian and Oneota cultural influences, centered in west central Illinois and Wisconsin, respectively, were characterized by increasing social-political complexity made possible by corn-based agriculture. Ultimately the familiar tribes emerged, in northeastern Illinois the Miami followed by the Potawatomi.

For a time in recent years, a group of researchers attempted to make the case that a comet or other extraterrestrial object exploded over North America, causing a climatic cooling (the Younger Dryas time), ending the Clovis culture and resulting in the extinction of the North American megafauna. By the end of 2010 a number of studies had invalidated the supposed evidence for this idea and shown that the Younger Dryas was the result of a sudden influx of cold, fresh glacial meltwater into the northern oceans that for a time shut down the Gulf Stream current.

Marsh Visitors

by Carl Strang

Yesterday we looked at one of the residents of Mayslake Forest Preserve’s stream corridor marsh, a predaceous diving beetle. Today’s focus is on a pair of migrant visitors, buffleheads, the first I have seen on that marsh.

The male is on the left, female on the right.

I have seen some of these ducks on the much larger May’s Lake, but seldom on such a small body of water. They seemed content, though. They liked it so much they stayed at least two days. Much of the time they were diving, and apparently finding enough insect larvae and snails to satisfy their needs.

I moved slowly, and never directly toward the birds, as I worked around the marsh. They stayed away, but never seemed alarmed.

I timed a few dives, and at 12-16 seconds the ducks were beneath the water about the same amount of time as when I observed members of this species on the much deeper Lake Maxinkuckee (at Culver, Indiana) in my youth. Their extended visit is yet another testimony to the improving quality of that marsh in response to restoration work around it.

Predaceous Diving Beetle

by Carl Strang

Ponds and marshes are fascinating places. Children love them because they are full of diverse and hidden life. Dip in a net and who knows what you might catch? This week I began monitoring some amphibian traps in Mayslake Forest Preserve’s marshes. I haven’t caught any frogs or salamanders, yet, but on the first day a few traps contained some large beetles. I thought I recognized them, but aquatic invertebrates are a weak point and I needed to do a little background study. I went back yesterday equipped with a water container, and when I caught one of the beetles I plopped it in.

The beetle swims with the hind pair of legs. The feet are fringed and act like oars. You can see the air bubble at the tip of the abdomen. The beetle breathes air from a bubble held beneath the elytra, or hardened top wings.

I first needed to see the antennae. There are two families of swimming beetles with some species reaching an inch or more in length. As you can see, the antennae are long and threadlike. That places this insect in the predaceous diving beetle family, Dytiscidae. The large size, color pattern and other details as well as their abundance in this marsh led to an identification of Dytiscus verticalis.

This gives some sense of Dytiscus’ size, an inch and a quarter long. They fold up tightly when lifted out of the water.

The top photo reveals rows of striations down the length of the elytra, which indicate this is a female. I learned in my reading that adults can live 2-3 years, impressive for an insect. The larvae, also aquatic, are predaceous like the adults. They are biters, so I wouldn’t have held a larva in my hand. They feed on small invertebrates, but also on tadpoles and tiny fishes. They are themselves on the menu for a variety of herons, larger fishes and other predators. The larvae have been shown to be flexible foragers, sitting and waiting when prey densities are high, going on the prowl when prey are fewer. Though both larvae and adults are aquatic, pupation takes place on land, and pupas can drown if water levels rise above them in that stage.

I’m looking forward to finding what else is in Mayslake’s marshes.

Wood Duck Dossier

by Carl Strang

I established my vertebrate species dossiers in the 1980’s as an antidote to relying too heavily on the scientific literature and the stories of others for my natural history knowledge. I wrote everything I could remember about each species from personal experience, which generally was embarrassingly little. Then I began to add notes as I made new observations to beef out the files. Each subsequent entry begins with my date code: the day of the month, two-letter month code, and year.

The male wood duck is one of our most beautiful birds.

Duck, Wood

 These are common around Culver, Indiana, in the Lafayette area, and in DuPage County. They nest in tree cavities, and commonly roost in trees. Wood ducks feed on land and in shallow water. The female has a loud squealing call that rises in pitch: “Coo-ah-lee”. The downy young are more cream colored than those of mallards, and lack the black stripe between eye and bill. They stay with their mother at rivers or wooded ponds. In flight, the wood duck appears dark, with a long tail and very narrow white rear edges of wings.

My experience with wood ducks began early. Here I’m 18 months old. We didn’t hunt wood ducks often, focusing more on other species, but a mounted one shot by my grandfather occupied a prominent place in the home.

 18AP87. A pair landed on elevated oak limbs (2 trees near one another) at the edge of woods between Mack Road and McKee Marsh, Blackwell Forest Preserve. One duck immediately took off, the other disappeared. Its tree has several holes about 30 feet up which could be nest entrances, and is 100m from the edge of the marsh.

26JL87. A mother with at least 3 half-grown young swimming out on Hawk Lake near Culver.

4AP99. First of year arrived, DuPage County, IL.

22AP00. Male spotted standing on high tree branch near East Woods Trail, Morton Arboretum. The tree was near the edge of a clearing with a wet area. He was uttering a faint, rising, zipping-whistling note, and occasionally throwing his head straight back until the beak pointed straight up momentarily before the head quickly returned to the neutral position. The female, who had been several trees away, came into view after I had been watching the male a few minutes. He seemed to be watching me, too, and it is possible the display was a displacement behavior.

23AP00. Red Oak Nature Center. Here beside the Fox River, there are lots of wood ducks this morning. One pair behaved much like yesterday. The male and female were perched in adjacent trees, the male higher than female. He did the same call and display as before, both birds watching me, then they flew off (female flew first, followed by male).

26FE01. The first wood ducks of the year were a group of 4 on the West Branch of the DuPage River at McDowell Forest Preserve. At least 1 bird of each gender was in the group. They were in a smaller stream going around one of the islands, but went to the main river (which is very high) after I flushed them.

3NO01. About 10 wood ducks were in a woodland pond at Herrick Lake, north of the big trail loop and south of the former youth group camp. Many mallards also were there.

20JL02. A mother wood duck with around 8 newly hatched ducklings were swimming off the west end of Culver’s Town Park in the early afternoon in the midst of Lakefest, with speedboats all around and one nearly running them over. Brice [my youngest nephew, now a student at Virginia Tech] and I were in kayaks going past. He was fine with going out to rescue them. We tried to stay far enough off to avoid alarming the mother too much, but it was necessary to stay closer than I would have liked, to keep the speedboats off them. Gradually we herded them in closer to shore and eastward, until finally she was 50 yards or so off a stretch of shore free of humans. She led her ducklings in, and they climbed up on shore. She had been trying to go west, toward town, and out farther from shore, but with the crowds and boats, I don’t see how the ducklings would have survived.

6MR09. Mayslake. First wood ducks of the year (2 pairs).

17MR10. Mayslake. First wood duck of the year (single female).

Last fall, Mayslake Forest Preserve’s stream corridor marsh hosted large numbers of wood ducks, often 30-40 at a time.

15MR11. Mayslake. First wood duck of the year (single male).

The Owls Persist

by Carl Strang

Mayslake Forest Preserve’s great horned owls are not raising any young this year, as I mentioned recently. They still are around, however, despite that setback.

The eggs apparently never hatched.

On Friday I observed something I never have experienced before (at least, I find nothing similar in my great horned owl dossier or my memory). In the middle of a warm day, the male began hooting (though males are smaller than females their voices are lower pitched, and they generally produce fewer syllables in a call). After he hooted a couple of times, the female joined in. They proceeded to duet continuously for more than 15 minutes.

They remained perched in their favorite roosting area throughout, and were only a few trees apart, so these weren’t contact calls, and the owls weren’t chasing away a territorial intruder. The only times I have heard such lengthy periods of display in this species have been at dusk and at night, typically beginning in November when the birds are re-establishing their territories.

 I have only a wild guess, here, as to what was going on. Reproductive behavior is hormonally regulated, and those hormones do not switch on and off quickly. With the failure of their nest those owls still have elevated (though probably diminishing) reproductive hormone levels. Energy that would have been going into feeding and brooding nestlings has no release, and so this peculiar lengthy duet was a result. Were the owls feeling anything? While it is tempting to attribute emotions to such a display, we cannot know what the experience of a bird is like. I won’t go so far as to say the owls weren’t feeling anything (we also cannot say that birds don’t feel emotions similar to ours), but will leave such speculation to others.

Prehistoric Life 18

by Carl Strang

This year’s winter series is a review of the prehistoric life and geologic history of northeast Illinois. Each chapter will summarize current understanding, gleaned from the literature, of what was going on with life on Earth in a particular span of time, what we know about the local landscape, and what we can say about local life. I include some references, particularly to papers published in the journal Science which commonly is available at public libraries. Contact me if you need sources for other items. The Earth is so old that every imaginable environment was here at some point, from ocean depths to mountaintops, from equatorial tropics to tundra, and from wetlands to desert.

Pliocene Epoch (5.2-1.64 million years ago)

The Pliocene Epoch, literally “more recent,” originally was defined (1833) by the percentage of then known fossil mollusk species still living (35-95%). Its end is marked by the beginning of the glacial times.

Life on Earth. In the Pliocene, grazers became largely supplanted by more generalist herbivores as savannas became widespread in Eurasia and North America. The dominant groups were camels, antilocaprids (e.g., pronghorn “antelope”), and Equus horses (which, like most horses, originated in North America). Opossums diversified in South America, mammoths appeared in Africa (early Pliocene), the North American rhinoceroses vanished (middle Pliocene), and Sorex shrews appeared in the late Pliocene.

Sorex shrews like our short-tailed shrew of today made their evolutionary appearance in the Pliocene Epoch.

Land bridges finally allowed camels to spread into South America and Asia in the Pliocene (a camel survived in North America into late Pleistocene times). In the middle Pliocene, continued connection to Asia brought immigration of more carnivores, deer, and the elephant Stegomastodon. From North America to Eurasia went a rabbit, a squirrel, the beaver, and Equus.

The world’s lynx and cheetahs first appeared in North America, crossing to the Old World via the Bering Sea land connection.

In the late Pliocene, new appearances were pocket gophers, the white-tailed deer genus Odocoileus, raccoons, the giant beaver, bobcat (Old World lynxes, and also cheetahs, trace their ancestry to the New World where their groups first appeared), the New World porcupine family, eastern mole, and masked shrew.

Modern deer made their appearance in the Pliocene.

In the meantime, the first hominids were beginning to walk upright in Africa 3.8-4 mya (million years ago; Science 307:1545). Upright walking may have begun in the trees, as a hand-assisted way of negotiating thin, flexible branches (Science 316:1328 ). “Lucy,” Australopithecus afarensis (3-3.6my ago), regarded as a human ancestor or close to it, has been tied to the older A. anamensis (4mya), which in turn may have come from the still older Ardipithecus ramidus (4.4mya). Fossils of all three species were found in the same African river valley (Science 312:178). Ardipithecus significantly was a woodland dweller; apparently upright walking was not a product of a grassland habitat (Science 326: 64). Genus Homo had evolved by the late Pliocene, with species from Africa to Asia. Homo habilis and H. erectus are two earlier species which apparently overlapped considerably in time, so that it is uncertain whether the latter descended from the former (Science 317:733). Examination of limb structure points to habilis being arboreal while erectus was terrestrial, so a connection by descent is unlikely (Science 320:609).

The New World chickadees evolved from a single species that emigrated from Eurasia in the Pliocene.

Birds also were dispersing, and our modern species began to emerge. At least some modern songbirds had evolved by the early Pliocene (Auk 124:85). The chickadees and titmice, which had appeared in Eurasia originally, came over to North America in the Pliocene. The first crested species (titmouse) came over around 4 mya, and a single non-crested (chickadee) founder species around 3.5 mya. Subsequent evolution led to the 3 modern titmouse species and about 7 chickadees in the Americas. One terror bird species, in genus Titanis, reached North America from South America 2-3 million years ago, but was extinct by the end of the Pliocene.

Local landscape. Cooling and increased seasonality continued in the Pliocene (the middle Pliocene was the last time that Earth temperatures were warmer than at present).  Climate in the early Pliocene was significantly warmer than today; the major difference apparently was that the El Niño pattern of Pacific Ocean currents was permanent rather than episodic as it is today. The re-establishment of such a pattern is a possible outcome of global warming (Science 312:1485). Woodlands were more open in the Pliocene, perhaps savanna-like in places in our area. Elsewhere in North America, the continent developed its first near-modern boreal forest, as well as the first deserts, tundra and permafrost areas.

The Pliocene brought increasing seasonality, and extensive savannas replaced much of the Miocene grasslands.

The nearest Pliocene deposits are tiny areas in southern Indiana, and extensive areas in eastern Nebraska. By the Pliocene, much of northeast Illinois was draining eastward into the river that ultimately was enlarged by Pleistocene glaciation to become Lake Michigan. This happened when the relatively erosion-resistant and eastward-sloping Niagaran dolomite beneath us was brought close to the surface. Today, surface waters are directed by much more recent glacial deposits on top of that bedrock, and all ultimately flow into the Des Plaines-Illinois River system, ending up in the Gulf of Mexico rather than the North Atlantic.

Local life.  There is a likelihood that the camels, antilocaprids and horses (including Equus, the genus that includes modern horses) were represented locally. Deer, rabbits, beavers, raccoons, sabertooth cats (including Meganteron, an ancestor of the famous Smilodon), bears, the scavenging “hyaenoid dog” Borophagus, otters, and skunks are other likely species at that time.

Spring Ooching In, Part 2

by Carl Strang

Yesterday I marked the physical advance of the spring season. There also have been plenty of biological signs. Sandhill cranes have been coming over on days with south winds.

Sandhill cranes are a favorite of all the Mayslake staff.

Silver maples have been flowering for more than a week.

This photo is from an earlier year.

The woodpeckers have been drumming like crazy.

This downy woodpecker found a particularly resonant sounding board.

Two days ago I saw Mayslake’s first bluebird of the year.

The bluebird appropriately was foraging in the middle of the north savanna.

Finally, yesterday the first chorus frogs started singing.

The years should have taught me patience by now. But spring ooches its way in, slowly warming, then backing off in another cold spell. I need to come up with an inquiry to keep me focused in this season, but the dreary month of March stifles my creativity. For someone who doesn’t believe in the reality of time, I certainly remain aware of its slow passage. But warm days like we’ve had this week are a soothing reminder of the season to come.

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