Archives For Jim Steffen

The Earth on its Back

Jim Steffen —  April 8, 2013 — 1 Comment

There is a Native American myth that is believed to have originated with the Onondaga tribe of the Iroquois nation of northeastern North America. It is a creation legend about how the earth (the land) was created. The legend incorporates a number of different animals including swans, pied-billed grebes, muskrats, and many others. The central character in the story is a turtle. The turtle, an island in a world of water, was chosen to carry soil and tree seedlings on its back, which eventually became the land the people lived on. So this story is about preservation and nurturing. Although this legend may have originated with the Onondaga, it is a common myth found throughout many Native American cultures.

The fact that the turtle myth was so widespread across the continent is not really all that surprising when you consider how many different species of turtles there are. There is a turtle species for just about every kind of wetland environment that exists, from sea turtles to bog turtles to  river cooters and pond sliders. There are approximately 17 species of turtles native to Illinois and nearly half of those occur at the Garden.

Other than birds, turtles are among the most common animals you are likely to encounter on any given day during the growing season at the Garden. Like the early blooming wildflowers in McDonald Woods, turtles are truly one of the first signs of spring. Soon after the ice melts on our lakes, turtles begin moving from the bottom of the lakes where they spent the winter hibernating. During the dark days of winter under the ice, turtles are able to slow their bodily functions down to the point where they can obtain enough oxygen to survive by absorbing it through the mucus membranes and tiny capillaries of their throat and cloaca (the common opening for defecation and egg laying). They also use some fascinating chemistry, part of which involves dissolving calcium from their shells to help neutralize toxic acids that would be fatal under normal circumstances. Still cold and sluggish from their long winter sleep, they begin swimming around near the surface, often poking their heads out to take their first real breath of air since descending to the bottom of the lakes in fall.    

Hoop trap for aquatic turtles

Hoop trap for aquatic turtles

Several years ago, I initiated a turtle project with one of the summer interns. We set out to try to determine how many turtles and how many species occur in our lakes. Utilizing a number of different live traps, we were able to count most of the individuals and almost all of the species that can be found here. Over three months, we were able to capture nearly eighty individuals of eight different species.

PHOTO: Floating trap for basking turtles.

Floating trap for basking turtles

The turtles can be divided into two general groups, those that like to bask (sun themselves on logs, rocks, or on the shore) and those that rarely bask. The basking turtles are the species most often encountered at the Garden. The most abundant member of this group is the red-eared slider. 

This is the turtle of dime-store fame. There was a time when it seemed like every kid had one of these sliders as a pet – do you remember Cuff and Link from the movie Rocky? They are distinctive, with a bright red slash along the side of their heads.  Although they are the most abundant species here, they are not native to this part of Illinois. Sliders have been introduced to many parts of the country where they had not previously been found. This is the result of all those dime-store turtles that grew up to be bigger turtles that were eventually released when their owners either ran out of room for them or the appeal of these long-lived animals wore off. Like many introduced species, the slider is aggressive toward our native species and as a result has achieved a dominant place in the turtle population.

PHOTO: The introduced red-eared slider.

The red-eared slider, named for the distinctive red patches over its ears.

PHOTO: False map turtle

Notice the narrow yellow bar on head of the false map turtle.

PHOTO: Underside of false map turtle

Topography-like lines mark the underside of the shell of this false map turtle.

PHOTO: Ouachita map turtle

Notice the square yellow blotch behind the eyes of the Ouachita map turtle.

The slider is not the only introduced turtle at the Garden. Some other species that can be found here that were not known in the region historically include the three-toed box turtle, the false map, common map, and the Ouachita map turtles.

Releasing pet turtles is not a good idea. The slider has greatly changed the dynamics of natural turtle populations all over the country. Some species, like the box turtles, which are terrestrial species that do not hibernate in lakes, are sometimes found at the Garden only after they have died after not being able to survive the winter here. There is also the possibility of spreading diseases.

The native turtles found at the Garden include the Midland painted turtle, Western painted turtle, stinkpot or musk turtle, spiny soft-shelled turtle, and the snapping turtle. The stinkpot and the snapping turtles are members of that group of more aquatic turtles that do not typically bask on logs or rocks. So although the snapping turtle is a common species at the Garden, it and the stinkpot are not seen nearly as much as the basking species.

A spiny soft shell

A spiny soft shell

PHOTO: Closeup of the spiny soft-shelled turtle.

The spiny soft-shelled turtle’s snorkel-like nose.

PHOTO: Western painted turtle.

The western painted turtle

Where do these turtles get their names? The map turtle gets its name from the pattern along the underside of the shell and along its neck and head that looks like topographic lines on a map. The box turtle has a hinged plastron (belly) that allows it to pull its head and legs inside the shell and close the “doors” sealing out predators. 

Soft-shell turtles have a soft, leathery shell that bends and flexes like an old leather baseball mitt. They have a very low profile and look like a large, olive-colored drab Frisbee when they are basking on the lawn.  Painted turtles often have attractive red markings along the edge of their carapace (shell) and plastron. As far as the stinkpot turtle goes, I’ll let you guess why they have that common name. I’m sure that if you do some digging, you’ll be able to sniff out the answer.

The turtles are egg-laying reptiles. Their eggs are probably best described as leathery-shelled ping-pong balls.  During the summer, the adult turtles will haul themselves out along the shore and look for suitable places to dig a hole in which to deposit their eggs. At the Garden, turtles often choose to lay their eggs in the mulch around the tree and shrub planting beds, probably because it is a softer, easier place to dig. This egg-laying season is a dangerous time for turtles.  

PHOTO: Snapping turtle laying eggs.

Snapping turtle laying eggs

During this time they are out of the water, many encounter predators, and often cross roads looking for

PHOTO: Snapping turtle eggs.

Snapping turtle eggs

nesting locations. Once the eggs are laid, the turtle covers the eggs with soil and then retreats to the water, leaving the eggs and young to fend for themselves. Usually the eggs will hatch in 45-90 days, but sometimes, for individuals that lay their eggs too late in the season, they may overwinter.  Although turtles generally lay a good number of eggs (2-40 or more, depending on the size of the individual and species), the failure of those eggs is high due to predators. Skunks and raccoons are probably the two most frequent predators of turtle eggs, but almost any predator that comes across a nest is likely to take at least some.

What do these critters eat? Most species are omnivores. They eat a combination of plant and animal material. The common map turtle specializes in mollusks, like clams and snails that it crushes with its broad hard mouthparts. The spiny soft-shell is a fast swimmer and often feeds on fish. The red-eared slider is also omnivorous, but tends to become more of an herbivore as it gets older. It should also be noted that turtles perform a valuable ecosystem service as carrion feeders by feeding on dead fish and aquatic animals that would otherwise remain for long periods as they decompose. So you can think of turtles as sort of turkey vultures of the aquatic world – the sanitation squad.

Visitors frequently encounter turtles crossing the road at the Garden during the summer. Although the urge is strong to help the turtle back into the lake, don’t approach them too closely since turtle are very good at defending themselves and have long necks that can dart out and grab anyone or anything that gets too close. Turtles have very sharp-edged mouthparts and once they get hold of something, they don’t let go. Many a dog has lost a piece of its nose when getting too inquisitive about turtles.

If you happen to be visiting the Garden in summer and spot a turtle basking in the sun, try to see if you can figure out which species it is. Perhaps more importantly, if you spot a turtle, try to remember the Onondaga legend and the great responsibility bestowed on it to preserve the land and plants for the people.


©2013 Chicago Botanic Garden and my.chicagobotanic.org

Hidden Wings

Some butterfly species spend the winter hidden away, to emerge in early March.

Jim Steffen —  March 26, 2013 — Leave a comment

A walk in McDonald Woods in late winter or early spring might be uninspiring to many people because of the drab gray trunks of dormant trees and seeming lack of activity. You might see the occasional black-and-white flash of a downy woodpecker flitting from tree to tree, or spot a white-breasted nuthatch as it navigates upside down, probing for whatever bits of protein it might have missed on earlier explorations.  

But who would expect butterflies? After all, 80-degree days and abundant flowers overflowing with nectar haven’t even awaken in our minds. But they are here, at least those few species that spend the winter, hidden away as adult butterflies under loose bark, inside piles of brush, or maybe in an old woodpecker nest or hollow log.  

Even though I know they are here, it is still a surprise the first warm day in March when I spot a mourning cloak basking in the strengthening sunlight. As I approach for a better look, it is likely to spiral upward, erratically flitting off to another patch of sun.  

PHOTO: Side view of the question mark butterfly.

Question mark (Polygonia interrogationis)
© Carol Freeman

The mourning cloak, eastern comma, and question mark are three of the common woodland butterflies at the Garden that generate a brew of chemical antifreeze earlier in fall that allows them to survive the coldest weather winter has to offer. Instead of migrating like the monarch or spending the winter wrapped in a chrysalis, these three are adults, wings at the ready to take advantage of the first warm weather of spring.

The lack of nectar-producing flowers this time of the year does not deter them as they are perfectly happy to feed on sap from any of the branches that may have been damaged during winter storms, or drink the fermented liquid oozing from an injured willow or oak tree. Although butterflies are a generally short-lived organism, usually living only a few weeks, these three can survive for eight to ten months.

PHOTO: The Mourning cloak butterfly.

Mourning cloak (Nymphalis antiopa)
© Carol Freeman

The dark, purple-brown color of the mourning cloak gives it an advantage at this time of the year. Those richly colored wings, held out to the sides, act like solar collectors absorbing the sun’s energy and passing it on to the body where it raises the temperature of their muscles enough to allow them to fly.

The comma and question mark utilize a similar basking strategy. They often posses sun-absorbing, dark-colored under wings, which, when held closed against their bodies and perpendicular to the sun’s rays, elevate their temperature. The thermal boost gives this group of insects a head start on the season by allowing them to exploit a habitat at a time of the year when there are few other butterflies around to compete for precious resources.

Although these three butterflies are insects, and as you know all insects have six legs, these three belong to a group known as the brush-footed butterflies. They have modified fore legs that are smaller than their other legs and cannot be used for walking.

PHOTO: Question Mark butterfly.

Question mark
© Carol Freeman

If you get a chance to get a close look at one of them, you might be surprised to see that they are only standing on four legs. The other two are tucked under their heads.

Next time you think of taking a walk in the dormant woods, pick a sunny day when these not-so-fragile gems might be out and about, soaking up sun and supping on sap.


©2013 Chicago Botanic Garden and my.chicagobotanic.org

While checking the perimeter fence around McDonald Woods to see if there was any damage to the fence after a windy day, I discovered a large red oak that had lost its foothold in the frozen soil and had toppled over against a white oak. Since the tree was threatening to push the other oak over into the fence, I decided to cut the red oak down to save the white oak and the fence.

When trying to remove a leaning tree, you have to start at the base and work your way to the top as each section falls away. The base of the tree was good and solid, sending a shower of sour-smelling oak shavings flying from the chainsaw. When I got about halfway up the trunk, the saw began spewing dark brown flakes of rotting wood, and the sawing became easier. After a few more cuts, the trunk became mostly hollow and the top of the tree crashed to the ground.

Looking back at one of the middle sections of trunk, where the center was a rich dark brown from the rotting wood, I noticed a thick, white object shaped like the letter “C”.  

Bessbug Grub

A closer look showed the object to be a large grub from a beetle. These grubs are similar to the white grubs of Junebugs and Japanese beetles that you find in your gardens and lawns, but much larger. Although the rotten wood was frozen, I was able to split open the log, revealing a whole colony of 30 to 40 beetle grubs about 2 inches long and about a half inch in diameter. Each grub was cradled in a smooth-surfaced cell in the rotted wood. Even at temperatures well bellow freezing, the grubs were able to move enough to show they were alive.

As it turned out, these grubs were the larvae of one of our largest woodland beetles, known as the stag beetle or stag-horn beetle. These beetles are one of the myriad invertebrates active year-round, doing the important work of reducing fallen trees to rich organic soil that will help other trees grow and support the next generation of plants.

These beetles are members of the Coleoptera (beetles) and get their name from the large antlerlike mandibles (jaws) found on the front of the head of the males.  The females also have mandibles, but they not as impressive as those of the males. The large mandibles are used for territorial defense and also to protect the beetles from any birds or other animals that might try to eat them. The impressive “antlers” can look threatening to people when they first encounter them; however, they are not a serious threat to people and will only give you a pinch if you handle them roughly. It is not uncommon to find the large brown stag beetles around buildings near woodlands at night, when they are sometimes attracted to the lights.

These critters are fascinating, not only because they are social in the larval stage and can take several years to mature, but they can also produce an assortment of sounds that are thought to help with communication between the grubs. The grubs have a striated structure on the leg that allows them to produce sound (called stridulation), kind of like rubbing a spoon on a washboard. If you notice the dark-colored segment that looks distended on the end of the grub, it is the digestive chamber, where the wood the grub consumes is digested with the aid of microorganisms.  If you give one of these guys a gentle squeeze, you will notice a stream of liquified, dark brown wood coming from the tail-end of the critter. 

One last item of interest about these wood-grubbing dynamos is that they often carry a large population of mites around, clinging to their bodies. When I took a closer look at the grubs, I found dozens of whitish-colored tiny mites attached to each of their legs.  

Bessbug mites

This observation lead me to recall the verse by the Victorian mathematician, Augustus De Morgan:

Great fleas have little fleas upon their backs to bite ‘em,
And little fleas have lesser fleas, and so ad infinitum.
And the great fleas themselves, in turn, have greater fleas to go on,
While these again have greater still, and greater still, and so on.

These mites do neither the beetles nor the grubs any harm; they are just along for the ride and probably snacking on any choice fecal pellets deposited by the beetles. If you find yourself sitting on a log out in the woods, you just might be perched above a nest of developing stag beetles.  


©2013 Chicago Botanic Garden and my.chicagobotanic.org