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.

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Prehistoric Life 17

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.

Neogene Period (23.3 million years ago-present), Miocene Epoch (23.3-5.2 million years ago)

The Neogene Period (named in 1853) defines a time when a significant portion of fossil species (or at least very close relatives of them) still are in existence. The Miocene Epoch (established 1833), literally “few recent,” originally was defined by the percentage of then known fossil mollusk species still living (17%).

Life on Earth. Warming but continued dry conditions prevailed through most of the Miocene, giving way to renewed cooling in the late Miocene. This cooling was caused at least in part by the continuing growth of the Antarctic ice sheet. The resultant drop in sea level established land bridge connections from North America to South America and Asia. Continental growth, and also the rise of major mountain ranges, increased the seasonality of climate, and changed ocean circulation patterns, with upwelling zones probably setting up the conditions favoring pinniped (sea lion, etc.) evolution in the middle Miocene.

Harbor seal. Pinnipeds underwent a significant radiation in the Miocene.

Grasslands spread in the Miocene. The Perissodactyla had been the dominant ungulates, with their diversity peaking in the Eocene, but in the Miocene they declined (though rhinoceroses remained prominent throughout the epoch), while the Artiodactyla increased. The latter ungulates’ advantage may have been their ruminant digestive tract and complex high-crowned teeth, good for grazers (this was true of the larger division of artiodactyls; the pigs and hippopotami lack these specializations). Camels were very diverse in the Miocene, a remarkable example being the 12-foot-tall, giraffe-like browser Aepycamelus.

Bactrian camels, Brookfield Zoo. The camels, which had their start in North America, were very diverse on our continent in the Miocene.

The deer family appeared early in the Miocene in the Old World. By the middle Miocene, the diversification and evolution of horses was represented in part by the first one-toed species, Pliohippus of North America. Horses did not develop high-crowned molars until 4 million years after the grasses replaced trees as the dominant vegetation in the Great Plains, but their limb structure changed more quickly, so that they were able to survive by efficiently traveling longer distances between suitable habitat patches (Science 306:1467). Ungulate diversity peaked in the mid-Miocene, perhaps because frequent disturbance by the large proboscideans (gomphotheres and mastodons, which migrated into North America at that time) diversified the grassland savanna that had developed. Toward the end of the Miocene, however, much of the savanna gave way to grasslands, and there were extinctions of many of these ungulates and proboscideans.

Prairies and other grassland ecosystems spread into North America and became important here in the Miocene.

The departure of forests from much of North America is associated with the vanishing of primates from this continent.  Miocene land connections to South America and Asia resulted in significant immigrations and extinctions. Sabertooth cats and other Felidae first immigrated from Asia in the middle Miocene (ending the so-called “cat gap”).  Other new Miocene arrivals from Asia included bears, skunks, and badgers; from South America, ground sloths. There was a diversification of canids (dog family), mustelids (weasel family) and amphicyonids, though in the late Miocene the amphicyonids became extinct. The American white-footed mouse genus Peromyscus first appeared in the Miocene, and Spermophilus ground squirrels in the middle Miocene. Flying squirrels had their start in Asia in the early Miocene, with the split between Old World and North American flying squirrels happening in the late Miocene. The dominant carnivores in South America were marsupials in the Tertiary through the Miocene. The first member of the opossum genus, Didelphis solimoensis, showed up in the fossil record of Brazil in the latter part of the Miocene. Marsupials went extinct in North America in the Miocene, however.

Bears evolved in the Old World, and crossed the Bering Sea land bridge into North America in the Miocene.

Modern bird families were established in the Miocene, and the land bird orders other than the passerines underwent their great diversification. The passerine (perching birds) explosion began in the late Miocene. The first modern genera of birds began to appear in the Miocene, as well.

Local landscape. Subtropical forest of the early Miocene gave way to warm temperate to cooler temperate forests. The Texas gulf coast was swampy, so our climate very likely was at least as moist as today. We were between known areas of forests in New England that were warm temperate (hickories, chestnuts, hollies, mulberries, gums, oaks, buckthorns, elms, grapes) and shrubland-savannas on the Plains (invaded by grasses and prairie forbs as the Miocene progressed). The closest Miocene deposits are in western Nebraska, south central South Dakota, central Mississippi and SW Maryland.

Local life. Throughout the Miocene, browser-grazer pairs of rhinoceroses were found all over North America in savanna environments (the most common genera were Aphelops and Teleoceras, respectively; Teleoceras appears to have been a herding, and possibly semiaquatic species). If our area was more forested, we may have had only a browsing species. Rhinos became extinct in North America at the end of the Miocene. It seems likely that our area witnessed the transition from perissodactyl to artiodactyl dominance. Forms of rhinos (5 genera), tapirs (2 genera), horses (14 genera), dromomerycids (an extinct group of deer-like woodland browsers with horned males) and camels (5 genera, including the giraffe-like Aepycamelus) probably were here. The oreodonts were a diverse group of pig-like herbivorous artiodactyls, with at least 4 genera probably here in the Miocene. Carnivora would have been the dominant predators (diverse dogs, weasels, the large bears Indarctos and Plionarctos, “bear-dogs,” large cats, and the saber-toothed nimravid Barbourofelis), but there was also the entelodont Dinohyus. The Miocene also saw the arrival of the first proboscideans, or elephant relatives. These may have had a significant impact, killing the trees that they fed on and thus disturbing the vegetation so as to create more habitat diversity. There likely were 3 genera here, including two that were relatively elephant-like, and one that had shovel-like lower tusks that it probably used both to scoop up aquatic plants and to scrape bark from trees.

Snowmageddon Stories

by Carl Strang

I’ve grown to like the term “snowmageddon” to describe our recent big winter storm. The fact that we had several days to anticipate its arrival is a tribute to meteorologists’ improved weather forecasting in recent years. Thanks to chaos theory, improved models, and advances in computational power, we have a much better ability to forecast the weather than existed in ancient times (my childhood). One consequence in the present case was the opportunity to build a scary, delicious anticipation of the inescapable coming calamity several days ahead of its arrival. I’ve adopted a humorous tone here, but I also pause as I type to remember that lives were lost.

I have two stories to share, the home story and a limited start to the Mayslake story. I work for an elite organization, the Forest Preserve District of DuPage County. We seldom are shaken by flood or storm. However, the wise decision was made to close the preserves on the day of the storm. As a consequence, I stayed home, working on an on-line guide to singing insects that I have begun to draft, and shoveling my driveway in stages.

I started by shoveling a simple path from the front door across the driveway, then from the garage door down to the street. Average snow depth was around 18 inches.

The snow had been pushed by winds that, in the open, hit 50mph and more. It was howling around the house, but I’m sure the surrounding neighborhood reduced the wind speed somewhat. Of course, a consequence of reduced wind speed is snow drifts.

Here you can get a sense of the drifted deposit in my driveway.

My back yard was not as picturesque, just a single drift covering all but the tops of the tall prairie plants in my flowerbeds. Looks like I won’t be grilling for a bit.

The back yard is pretty full. The brats in the freezer will have to wait.

 I got the driveway cleared, just a bit of exercise, so that’s the end of the home story.

Mayslake likewise is deep in snow. A few days before the storm I managed to pull a calf muscle while running, so I haven’t waded out to see the entire preserve. Here was one interesting double drift that formed close to the mansion.

This double drift reminds me of the crescent dunes that form in some sand desert areas.

This snow will help some animals. Many wintering insects benefit from the protection and insulation provided by deep snow. Voles and shrews are less in danger from larger predators as they tunnel beneath the drifts. Some, like raccoons and skunks, simply can wait out the thaw for a while. Others, like deer and winter-active mammals and birds, must cope.

Here a coyote waded through the snow, continuing a hunt made more difficult by the storm. It could be worse: at least the blizzard’s winds packed the snow somewhat.

I was especially interested in how the owls would react. Mayslake’s great horned owls started incubating on January 27, just before the storm hit. I am happy to report that the female seemed unperturbed, and continues to sit the nest.

Trailing Strawberry Bush 2010

by Carl Strang

Last week I began to collect this autumn’s forest herbivore data. Today I’ll focus on the trailing strawberry bush at Meacham Grove Forest Preserve. In last year’s account of this study I expressed concern about a second controlled burn of this forest floor area in 3 years. The 2007 burn had knocked back the plants, and though they had recovered some in 2 years I wondered how they might respond to another burn happening so soon. I am not the only interested party, of course.

These deer I saw while collecting the data are affected by the fall burns, possibly for the better, and the removal of litter may help the plants by removing some insect herbivores. But it was clear that some trailing strawberry bush plants were scorched. As I checked my study colonies of the plants last week I found them looking green and scarcely touched by herbivory. They still are very small, and none produced fruit (2000 was the last year when any of the colonies fruited). Though they were smaller than in 2009, the difference was not statistically significant whether colony size was measured as overall length by width (median value of that product reduced from 5.5 square meter in 2009 to 0.95 in 2010) or by the total ground coverage of the scattered bits composing each patch (median value reduced from 0.28 to 0.1 square meter). Though some of the colonies now are very small, what remains appears healthy, and in general the fire appears to have reduced their competition from other forest floor plants.

Summer Woodland Wildflowers

by Carl Strang

In summer the main wildflower action shifts to prairies and other open areas, but in recent weeks there have been plenty of species blooming in the savanna woodlands at Mayslake Forest Preserve. Tall agrimony plants have been flowering for a while, now.

Tall agrimony 1b

These small yellow flowers will produce burs to be dispersed by mammals that brush past and catch the burs’ hooks on their fur or clothing. Another species that disperses in the same way is enchanter’s nightshade.

Circaea 1b

Named for Circe of Greek mythology, Circaea is an annual that I also could have included in a weeds update because of its “weedy” life history strategy. I expect to be pulling many of its tiny burs off my shoelaces later in the season.

The flowers of Canada black snakeroot are so tiny that they are easy to miss.

Canada black snakeroot b

Also small are the flowers of white vervain, but they at least are in strings at the tops of relatively tall plants.

White vervain b

Speaking of tall, here is a more conspicuous bloomer common in a wide range of our woodlands.

Tall bellflower

Tall bellflower was the subject of a study published last year that interested me (Yang, Louie H. 2008. Pulses of dead periodical cicadas increase herbivory of American bellflowers. Ecology 89:1497-1502). Yang experimentally fertilized plants of this species with the bodies of periodical cicadas, and found that deer preferentially fed on treated plants. This was a new demonstration of how the cicadas’ abundant emergences  have a profound ecological impact.

The shorter blue-flowering plants of self heal occur in woodlands and in the open.

Self heal b

Incidentally, lowering my sights one day as I walked the slope between the friary and May’s Lake, I saw the following plant.

Ginkgo seedling 2b

Unless I am mistaken, this is a ginkgo seedling. The closest female ginkgo trees I know of are a half mile away, on Mayslake’s Peabody Mansion grounds, though there is a residential neighborhood just west of the friary that might have others. Their fruits are notoriously smelly to us, but apparently were acceptable as food to a bird.

Among the most recent flowers to appear are those of the nodding wild onion.

Nodding onion b

I’ll conclude with a couple of species that occur both in open woodlands and in prairies: Culver’s root

Culver's root b

and, most spectacular of the lot, Michigan lily.

Michigan lily 1b

These are few and scattered wherever they occur, so remember to enjoy them in place and resist the temptation to (illegally) pick them. Flowers generally are protected on all forest preserves.

Just Passing Through

by Carl Strang

The first deer to visit Mayslake Forest Preserve since January 12 came through at night on April 28/29. I didn’t see them, but the soft mud from the seemingly incessant recent rains made the tracks easy to see, and not much time was needed to trace them, following them some times, cutting their trail at others.

buck-track-29ap-2b

I was interested in the number of individuals, and their gender. I have not yet learned the pressure release  that indicates gender, but with so many tracks I could use the quick and dirty method confidently. In does the hips are wider than the chest, and in bucks the chest is wider than the hips. Comparing the placement of front and hind feet in the diagonal walk gait  when the deer were walking straight, I found that there were two bucks.

This was disappointing; I am hoping that at least one doe will have her fawn at Mayslake this year, but so far no dice. The bucks apparently entered the preserve by crossing 31st Street, followed the stream south, spent a little time on the south mansion grounds, then backtracked a little, passed north of the stream corridor marsh and on into the savanna. They acquired the main trail at the northeast corner of May’s Lake, followed it south along the edge of the lake, and at the southeast corner turned off the trail and followed the lake’s edge on out of the preserve. After spending some time in the residential neighborhood they returned to the preserve, retraced their route along the lake and continued to follow its edge all the way to the mansion grounds. I picked them up at the prairie north of the mansion, and they exited the preserve at its east boundary, not far from 31st Street.

In short, they covered most of the preserve and then left. Bucks wander widely and erratically, and I expect to encounter signs of these two again, but not necessarily soon. They were just passing through.

Dem Bones

by Carl Strang

 

The four deer at Mayslake left the preserve when the deep snow came in mid-winter, and have not yet returned. The next significant time for them will be the birth of their fawns. The does at this time of year are deciding where to have their summer ranges with their fawns. If none come to the preserve in the next few weeks, Mayslake probably will be without deer this summer.

 

Last week I came upon bones of a deer near the stream. The animal died at some point well before my arrival at the preserve last November. Concealment by snow and fallen leaves prevented my finding them sooner. The following account is my preliminary assessment. The first bone I noticed was the main part of the skull. The lack of stems for antlers indicates that the animal was a doe.

 

deer-bones-1b

 

Close to the skull were a couple vertebrae and a femur, or upper back leg bone.

 

deer-bones-2b

 

The teeth were not greatly worn, but the size of the bones indicated that the doe was full grown, and presumably in a prime time of life.

 

deer-bones-4b

 

About 15 feet away were bones from two legs in another little cluster. One of the legs was a front one (note the odd, shorter, triangular-shaped ulna in the center), and one was a hind leg (beside the ulna is a heel bone).

 

deer-bones-5b

 

Another hind leg was 10 feet above the skull on the slope, and 15 feet from the second (two-leg) cluster of bones.

 

deer-bones-6b

 

About 20 feet from the skull in the opposite direction from the two-leg cluster were a few ribs and vertebrae, one of the shoulder blades, and a piece of skull.

 

deer-bones-9b

 

Below those bones were those of the other front leg.

 

deer-bones-7b

A few feet farther was the other femur.

 

deer-bones-10-turned-b

 

I did not find bones from the pelvis, the other shoulder blade, one humerus, or most of the vertebrae and ribs. No skin or hair was present. I don’t have much experience reading this kind of bone scatter, so I’m enjoying the puzzle. I think my bone identifications are accurate. The site was more than 100 yards from 31st Street, and none of the bones I saw were broken, so cause of death cannot be assigned to the doe’s being hit by a car. The remaining bones, if I can find them, may change that conclusion. The clustering of bones in several well separated groups over a 40×15-foot area suggests to me that the deer’s body was pulled apart, almost certainly by two or more coyotes, for consumption. But whether the coyotes had any role in the doe’s demise cannot be said. A healthy doe should be able to avoid predation, but experienced coyotes working as a team conceivably could catch an animal by surprise. Alternatively they may have scavenged a deer killed by something else. For large chunks to come apart like this (in particular, for the skull to come apart the way it did), it seems to me that some decomposition must have occurred prior to the tug-of-war.

Culver, February

by Carl Strang

 

Over the weekend I visited my parents back in my home town of Culver, Indiana. It is located in Marshall County, one of the second row of counties south of the Michigan border, and is south of South Bend. The climate there is a little warmer than in northeast Illinois, but not by much. Still, I hoped for signs of spring on a Saturday afternoon walk. I reached the town park.

 

beach-lodge-b

 

Whenever I see the Beach Lodge, in my mind’s ear I hear the sounds of pinball machines, the steel balls bouncing off bumpers and ringing bells. I feel the grit of sand and recall memories of summer odors. On this day, though, the beach was empty of sun bathers and swimmers. A couple of deer had come out of the adjacent woods onto the beach on both previous nights, then turned back.

 

deer-tracks-culver-2b

 

Lake Maxinkuckee still was frozen, though the edges had melted so that in most places there was just a thin skim of new ice. Sand still was piled where the expanding lake ice had bulldozed it earlier.

 

maxinkuckee-ice-edge-b

 

A single ice fisherman had found a way onto the thicker ice away from shore.

 

ice-fisher-4b

 

It turned out he had gotten there at the beach. You can see the tracks of his sled on the sand as he sought a place where thicker ice reached the edge (the tracks are highlighted here because I am facing the sun).

 

ice-fisher-tracks-1b

 

Here is where he took his first steps out.

 

ice-fisher-tracks-2b

 

I went on to the woods, which belong to the Culver Military Academy and are known locally as the “Indian Trails” as they contain footpaths connecting the academy to the town. Near the lake is a small swampy area, and there I found the sign of spring I sought: skunk cabbage flowers.

 

skunk-cabbage-2b

 

These are renowned for their ability to metabolize enough heat to grow through snow and cold soil, bringing their flowers within reach of insects that are activated by the warmer early spring days. But I also found something unexpected.

 

february-cotyledons-b

 

A seedling! I couldn’t identify the species, but clearly a seed had sprouted in February. I don’t remember seeing such a thing this far north before, but maybe I just hadn’t paid close enough attention. It wasn’t jewelweed, which can grow in such places but germinates later and has wider cotyledons. Skunk cabbage? I don’t know. I filed it away as another of those mysteries that sit in the back of the mind as inquiries to be attended, perhaps, later.

Poison Ivy as Browse

by Carl Strang

 

Each month brings its own features of interest, its own associations. I have already covered how skunks go on walkabout in February. Another peculiarity of February in northeast Illinois is the sudden preference deer and cottontails have for poison ivy as a food item. Poison ivy was last conspicuous to our eyes in the fall, when it displayed its bright autumn coloration.

 

poison-ivy-color-b

 

Since then it has been its dormant winter self, recognizable by its vine growth form (older vines connected to tree trunks by masses of dark brown or black hairlike projections) and the curved, yellow-brown, finger-shaped buds, visible on two of the three twig ends in the following photo.

 

poison-ivy-browsed-b

 

But it’s the third twig end that is of interest here. It has been browsed by a deer. If we had seen the deer taking this bite, it would have been standing to the right of the photo and facing left.

 

Through the winter, deer and cottontails change their diets, but in a given month both are eating much the same thing. They are mainly browsers in winter, nipping off live twig ends for the nutritious inner bark and buds. Early in the season they favor members of the rose family like raspberries and roses. In the middle part of winter they shift to a long list of favorites. Rabbits also eat the bark from parts of shrubs they can reach, and take advantage when live branches are broken off in winter storms, as the example from last month illustrated.

 

In February, northeast Illinois deer and rabbits favor poison ivy. Whether this is because that plant undergoes some chemical change that renders it palatable at that time, or whether that is when the more preferred plants have been depleted, or whether it is for some other reason, I do not know and haven’t the laboratory to test such hypotheses. But I suspect that deer and rabbits on the preserves would have a much harder time surviving late winter if it weren’t for poison ivy.

 

Distinguishing whether a cottontail or a deer is the browsing animal in a given case is fairly straightforward. Rabbits, in addition to being shorter and having a more limited reach, have incisor teeth on both jaws. When one nips off a poison ivy or other twig end, the bite is a clean cut at an angle. Deer have incisors only on the lower jaw. A deer bites part way through the twig, pinching against the hard upper jaw, then twists and pulls to remove the bite from the plant. The lower jaw side is cleanly cut, but the upper jaw side is torn.

Antlers

by Carl Strang

 

Today I want to have some fun by sharing antler shots. When I was following the deer at Fullersburg, I was impressed by how distinctive the antlers of each buck were.

 

buck-21oc-1b

 

Antlers are bony structures grown from scratch each year, developing through the spring and summer and shed in late winter.

 

buck-15my08-1b

Hunting-oriented literature correlates antler size and shape, and the animal’s body features with its age.

buck-8no-1b1

 

How precise those judgments are I cannot say from my own experience, but certainly it takes at least a couple years’ growth for a male to reach his full body size and grow large antlers, and only a few individuals achieve the largest size of body and head ornamentation.

 

buck-22oc08b1

 

Incidentally, the purpose of antlers is to support the buck’s pursuit of females in the rutting season. Large body size and large antlers intimidate smaller males and attract the interest of does. Antlers have their branched structure for instances when males won’t back down from one another. The object of the resulting combat is not to cause injury, for instance by using the sharp antler tines as piercing weapons. Rather, the antler forks provide purchase. The opponents engage their antlers and attempt to push one another around. The winner is the one who succeeds, and the loser retreats.

 buck-17se3b

 

One question that came to me was the genetics of antler structure. In each of the first two winters of my Fullersburg study, one buck stood out from all others. I cannot say whether it was the same individual in those two seasons, but I’m inclined to think so. There were distinctive structures, downward pointing branches called “drop tines.” I called this deer “Mr. Big.”

 

buck-mr-big-2-8no06b

 

No deer approaching Mr. Big’s size appeared last winter. However, there were two enormous bucks hanging out together all last summer at Fullersburg. One of them, who I inevitably thought of as “Son of Big,” had drop tines. Tempting, tempting to attribute these patterns to genetics.

 

The two bucks in July

The bucks in July

 

 

 "Son of Big," September
“Son of Big,” September

 "Son of Big's" partner, September

"Son of Big's" partner, September

 

How I wish I could have seen what happened between those two males when the hormones were flowing in November!

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