Archives For Ecology & Wildlife

The Chicago Botanic Garden is actively maintaining, restoring, and recreating four natural areas at the Garden: woodlands at McDonald Woods and the Brown Nature Reserve, the Dixon Prairie, the Skokie River Corridor, and the 60-acre Garden Lakes. These activities teach restoration ecologists a great deal about habitat management, which can be applied in other regions.

Bees in the Big City

Andrea Gruver —  August 15, 2018 — 3 Comments

The plants you see from your train seat on the Metra Union Pacific North line may help conservation scientists learn about how urban areas impact native bees.

Although most people think of honeybees when they think about bees, there are more than 4,000 native bee species in the United States and 500 species in Illinois alone. Like their honeybee counterparts, native bees are undergoing global declines, making them an important conservation concern. With the growth of urban areas, native bees may be faced with new challenges, yet we don’t know the extent that urban areas impact native bees.

My research at the Chicago Botanic Garden is investigating how urban areas may affect native bees in Chicago. Chicago is an ideal city to study the impact of urbanization on native bees because the intensity of urbanization slowly wanes from the urban core of the city out into the surrounding suburbs.

Megachilid (leaf cutter) bee

My research is focused on native bee species in Illinois like these Megachilid(leaf cutter) bees.

Megachilid (leaf cutter) bee

Part of that research is about bringing public awareness to the other native bees we have around Chicago.

To explore native bee communities along this urbanization gradient, I have a series of eight sites along Chicago’s Union Pacific North Metra (UP-N) railway. I chose the sites along the rail line because they followed a perfect gradient from very urban to very suburban. I was also drawn to them because most of the vegetation around the sites is unmanaged and composed of similar species.

All of the sites vary in the levels of green space and impervious surface (concrete/buildings) surrounding the sites. Sites near downtown are surrounded by nearly 70 percent impervious surface, while sites near the Chicago Botanic Garden are surrounded by just 15 percent impervious surface.

[Click here to view video on YouTube.]

Studying bees in this area along the Metra line allows us to ask a variety of questions about native bees. For instance: Are there fewer bees in highly urban areas? Are there different bees in natural areas compared to urban areas? Do the bees in highly urban areas have different traits than those in natural areas?

Pollinator Collection Near the Metra with Andrea

Andrea and an intern collect bees along the Metra line.

This summer, a few interns at the Garden and I have been gathering and sampling bees at each of my eight field sites. To catch the bees, we use two methods. First, we set out fluorescent colored bowls with soapy water that attract and capture the bees. Secondly, we use a butterfly net to capture bees at the site throughout the day. When we are finished sampling, the bees are taken back to the lab at the Garden’s Daniel F. and Ada L. Rice Plant Conservation Science Center and pinned for future study.

In addition to collecting the bees, we also record all of the flowering plants and count how many flowers are blooming at the sites.

Although our days are currently filled with fieldwork and pinning, in the fall we will spend almost all of our time in the lab identifying the bees down to the genus or species level. When we have all of the bees identified, we can then start analyzing the data for my master’s thesis and answer some of the questions we have put forth. We suspect we will see a higher abundance and diversity of bees in sites located in more natural areas with more flowering plants.

My research will help us understand how urban areas are shaping native bee communities and help us determine what landscape features promote native bee diversity in urban environments, some of which can be implemented in urban restoration projects. We also hope that this work will illuminate the amazing diversity of native bees we have here in Chicago.


©2018 Chicago Botanic Garden and my.chicagobotanic.org

If you happened to walk around the Heritage Garden in late June, the unusual blue color of the Moroccan mountain eryngo (pronounced eh-RING-go), Eryngium variifolium, probably caught your eye, and its peculiar perfume tickled your nose. It was also swarming with flying insects.

The odor was not lovely and sweet. I would describe it as similar to musty, molding fruit—not unpleasant, but certainly not a fragrance you would wear. It only lasted a few days, during which time it hosted an amazing number and variety of insects. I attempted to photograph and identify as many of them as I could. This was a lot harder than I expected, because the insects were in constant motion and most of them were small. I didn’t always capture the key features needed to identify them at the species level. In spite of this, you’ll see that that the variety was astounding. Let me introduce you to what I found at the Chicago Botanic Garden recently.

1. Carpenter bee

PHOTO: a carpenter bee perched on a eryngo flower.

Carpenter bees are often confused with bumblebees because of similar size and coloring. The carpenter bee has a black abdomen and a black spot on the back of its thorax (middle section). That’s how to tell the difference.

2. Mason bee

PHOTO: a mason bee on an eryngo flower head.

Mason bees are in the Megachile family. The are also known as leaf-cutter bees.

PHOTO: a megachile bee is covered in pollen.

This mason bee has filled the “pollen baskets” on its hind legs with pollen from the eryngo, and they are now swollen and bright yellow. Pollen is also sticking to the hairs on its thorax and underside. It is a good pollinator!

Carpenter bees and Mason bees are native to our region. Honeybees are not native to the United States. I saw honeybees in the Heritage Garden, but they were not interested in this flower. Honeybees tend to go for sweeter-smelling flowers.

3. Red admiral butterfly

PHOTO: a Red Admiral butterfly is perched on a eryngo flowerhead.

The red admiral, with its characteristic red stripe across the middle of the upper wings, is  common in our area.

4. Azure butterfly

PHOTO: the azure butterfly's wings are smaller than that flower head it is perched upon.

This tiny gray-blue butterfly is an azure. Some azures are the same blue color as the eryngo flower.

A monarch butterfly also flew overhead while I was taking pictures, but it didn’t stop by. Again, the scent of this flower isn’t attractive to all pollinators. 

5. Squash vine borer (moth)

The squash vine borer larva can be a nuisance in a vegetable garden, but it is a beautiful and beneficial pollinator as an adult moth. Sometimes we have to resist the urge to judge our fellow creature as being good or bad. 

PHOTO: Picture of the moth perched on an eryngo flower head.

The squash vine borer was the flashiest visitor I saw on the flowers.

6.  Syrphid flies (hoverflies or flower flies)

When we think of flies, we tend to think of those annoying houseflies or other pests, but there are other kinds of flies. The Syrphidae family, also known as hoverflies or flower flies, feed on pollen and therefore serve as important pollinators for many plants. I found three species of syrphid flies on the eryngo.

PHOTO: flower fly hovers next to the flower head.

Flower flies resemble bees because of their yellow and black striped pattern, but this little insect bears the large eyes and short antennae that are characteristics of a fly.

PHOTO: flower fly on a leaf.

This syrphid is very small, only about a a quarter of an inch long. It looks a lot like the first, but it had a rounder abdomen. The pointed end is an ovipositor, so after inspection, I believe this is the female and the other may be male, so I counted them together.

7. Another kind of syrphid fly

PHOTO: syrphid fly on a eryngo flower

This syrphid fly is a little bigger and fuzzier than the previous one. It could easily be mistaken for a bee.

8. Mystery fly, possibly another syrphid

PHOTO: small black fly on a eryngo flower.

I was having a difficult time getting good picture of some of these small insects, and as a result, I didn’t get enough details to identify this half-inch-long fly with white triangles on the back of its abdomen.

9. Green bottle fly

Houseflies fall into the family of flies known scientifically as Calliphoridae, also called the blowfly family, and they were also represented on our eryngo plant.

PHOTO: green bottle fly seen from the back.

One view of this green bottle fly (genus Phormica) shows its iridescent green body.

PHOTO: Green bottle fly from the front.

The same green bottle fly can bee seen with its proboscis sipping nectar from the flower in this image.

10. Cluster fly

PHOTO: cluster fly on a flower.

This is the only image I got of another blowfly species, a cluster fly (genus Pollenia).

11. Tiger fly (I think)

Tiger flies prey on carpenter bees, which were feeding on the eryngo flowers, so seeing this predator around the eryngo makes sense.

PHOTO: a fly of some kind is perched on a leaf, partially hidden by the stem of the plant.

I could not get a good picture of this one, because it was hiding in the shadows under the flowers. The wing pattern suggests some kind of tiger fly. Its secretive behavior is also a clue to its identity.

12. Vespid wasp

The wasps I observed were far too busy collecting nectar and pollen to notice me. I had no concerns about being stung.

PHOTO: wasp perched on a eryngo flower.

Vespid wasps are a large family of wasps that include paper wasps—those insects that make the big paper nests. These insects live in colonies and they do sting when they feel threatened.

13. Black garden ant

I watched a few ants appear very determined as they walked up the stems of the eryngo, dipped their heads into the flower centers, and went back down the stem as swiftly as they arrived.

PHOTO: Ant on an eryngo.

The ants must have a colony living in the ground under the Eryngo.

14. Damselfly 

Where there are a lot of flying insects, there are going to be some predators. There were damselflies hovering over the blossoms, feeding on the flies, not the flower. 

PHOTO: bronze and blue damselfly perched on an Eryngo flower.

Damselflies are difficult to identify without getting a really good closeup of their abdomens and markings—and my picture wasn’t good enough. I believe this is some kind of spreadwing.

15. Assassin bug

Assassin bugs fall into the category of insects known as “true bugs.” I saw few assassin bugs lurking around the eryngo flowers.

PHOTO: an assassin bug hangs out at the bottom of the flower, probably about to catch another insect.

Assassin bugs and their kin have piercing mouth parts that penetrate their prey and suck the juices out. This guy wasn’t there to feed on nectar or pollen.

16. A spider web

Like the damselfly and assassin bug, this spider is hanging out somewhere under the flowers to prey on the flies, bees, and other insects that happen into its web.

PHOTO: Spider web that was underneath the flowers.

Spiders tend to set their traps and hide. I never saw the spider that made this tangle-web but I suspect it was well fed.

In total, I found two kinds of bees, two butterflies, one moth, six flies, one wasp, one ant, one damselfly, one assassin bug, and one spider—sixteen different bugs on this one bright, smelly plant!

The take-away from my experience is that scent is a really successful strategy for attracting pollinators. Like the titan arum, the Moroccan mountain eryngo produced a super potent blast of odor for a brief period time and then moved on to the next phase in its life cycle, which suggests that it requires a lot of a plant’s energy reserves, and may not be sustainable for a long time. This strategy works well  as long as the timing of the bloom coincides with the pollinators’ need to feed and ability to get to the flowers. 

I find this phenomenon fascinating. If you share my passion for plants and their relationships with insects, check out Budburst at budburst.org and find out how you can help scientists who need your observations to contribute data to their research. 


©2018 Chicago Botanic Garden and my.chicagobotanic.org

At the Chicago Botanic Garden’s Butterflies & Blooms exhibition, I receive a wide variety of questions about butterfly physiology. My favorite questions are ones that don’t have a substantiated answer, only theories posited by lepidopterists (or those who study butterflies and moths). I always enjoy these questions, since they are on the cutting edge of scientific understanding.

One such question is: “What are those specs of gold on the monarch butterflies?” The short answer is “Nobody knows!” But there are a few interesting theories.

Zebra longwing chrysalis (Heliconius charithonia) top view, showing gold markings

Zebra longwing chrysalis (Heliconius charithonia) top view, showing gold markings; photo via BugGuide.net. Copyright © 2006 Hannah Nendick-Mason

Lepidopterists approach strange features such as metallic markings by asking, “What sort of advantage would this feature give to the butterfly?” Every trait found in nature exists because it gave that individual more opportunities to reproduce. Perhaps the trait helps keep the butterfly from being eaten, or it gives a male butterfly bright colors to impress the ladies, or perhaps it allows the butterfly to utilize new food sources when nectar isn’t available.

When butterflies emerge from their chrysalids, they are very vulnerable to predators like birds, since they can’t move. Their only defense is to display colors and patterns that either signal poison or blend into the environment. That means the features we see on chrysalids are no accident, as they offered an advantage and were subsequently passed down.

Camouflage is the prevailing theory as to why chrysalids sometimes have metallic spots, but wouldn’t a bright spec stick out like a sore thumb? One theory is that the specs imitate the iridescent glistening drops of dew on a leaf in the morning or after a rain.

Another theory is that the gold specs are a way of the pupae shouting, “I’m poisonous! Leave me alone or you’ll be sorry!” In the world of insects, reds, oranges, and yellows universally indicate poison, whether the insect is actually poisonous or not. Many insects, including butterflies and their pupae, use this trick to their advantage. My favorite trick is when a chrysalis has evolved to look just like a little snake. Imagine how shocked a bird or a bat would be when it discovers it’s next meal might actually make a meal out of it instead!

spicebush swallowtail caterpillar

Butterflies have adapted a variety of techniques to ward of predators while pupating, such as mimicking snakes or simply blending in. Photo by Judy Gallagher via Wikimedia Commons

Water drops in nature

One theory for the gold and silver spots found on chrysalids is to mimic water droplets.

While monarchs and longwing butterflies have gold specs, we often have species of butterflies that decided to have even more swagger by making their chrysalids appear to be solid gold. Guests often compare them to exotic gold jewelry. These pupae are so shiny, you can clearly see your own reflection in them—and that’s the point. What better way to blend into your habitat than to literally mirror it? This is the prevailing scientific theory, anyway.

Solid gold pupa

Pupae that are fully metallic are thought to blend in by literally mirroring their surroundings. You can actually see my phone and hands reflected in the chrysalids.

When you see a metallic spot on a butterfly chrysalis, you are seeing yellow and orange pigments, but it’s the intricate microscopic structure of the outer chrysalis that gives it its metallic sheen. This is where things get a bit more complicated. Entomologists refer to the outer surface of metallic chrysalids as “multiple endocuticular thin alternating layers.” That’s quite a mouthful, so they call it M.E.T.A.L. for short. The acronym fits perfectly.

Here’s another way to think of what you are seeing: Imagine a butterfly’s chrysalis as several thinly stacked layers of windows. When sunlight hits these windows, they absorb and reflect light, giving a glimmering effect.

In each phase of a butterfly’s life cycle, it is extremely vulnerable to being eaten. From slow, plump caterpillars to immobilized chrysalids to paper-thin, delicate adults, they’ve found ingenious ways to survive and reproduce. Come to Butterflies & Blooms and see for yourself.


©2018 Chicago Botanic Garden and my.chicagobotanic.org

Shrew-ed Observations

Jim Steffen —  December 12, 2017 — 3 Comments

Several years ago, while walking the nature trail in McDonald Woods, I stopped, having heard a high-pitched squeaking emanating from the sedges and grasses along side the trail. (This was when my hearing was still acute enough to detect such high-frequency sounds.) It took me a while, but based on the emphatic commotion, I finally realized I was hearing either a romantic interlude or territorial dispute between two of the smallest carnivorous mammals in our woodland: shrews.

Actually, shrews are technically known as insectivorous mammals. Insectivores are critters that depend, to a large extent, on invertebrates, mostly insects, for their survival. I wasn’t sure which shrew this was, but more than likely, it was one of the commonest species, the short-tailed shrew (Blarina brevicauda).

Blarina brevicauda by Gilles Gonthier from Canada [CC BY 2.0],via Wikimedia Commons

Short-tailed shrew (Blarina brevicauda) by Gilles Gonthier from Canada [CC BY 2.0], via Wikimedia Commons

 

The short-tailed shrew averages about 4.8 inches (122 mm) in length, with the tail being about a quarter of the length of the body and head combined. It is by far the largest of the shrews we will see here. They are generally a velvety, dark gray color and have a conical, pointed snout. The ears and eyes are quite small and are mostly embedded within the fur. To aid in moving through the environment, and perhaps catching prey, short-tailed shrews use a form of echolocation, similar to bats, to move around in tunnels and the dark of night.

These high-energy, secretive animals are active year-round, so their presence is more noticeable when the ground is covered with snow. If a healthy population exists in good habitat, it is not unusual to spot their miniature tracks trailing away from small tunnel openings in the surface of the snow. If you are particularly lucky, you might happen upon a real nature drama where an owl has captured a shrew, leaving behind a dead-end trail of tracks and wing patterns in the snow.

Imprints in the snow of a screech owl's wings tell the story of the shrew that didn't get away.

Imprints in the snow of a screech owl’s wings tell the story of the shrew that didn’t get away.

Although short-tailed shrews are primarily crepuscular or nocturnal in their habits, they are often spotted scurrying around during the day under bird feeders in winter or around woodpiles or similar habitats other times of the year. Most people who spot shrews believe they are seeing mice, voles, or moles. In fact, some of the common names for these critters include mole shrew or shrewmouse. Mice and voles are rodents, which have incisors—those chisel-like teeth for consuming plants and seeds. Moles, like the shrews, are insectivores. The shrews, being insectivores and occasionally preying on other small mammals, have teeth designed for ripping and tearing, not unlike miniature wolves or weasels.

The teeth of the masked shrew (Sorex cinereus).

The teeth of the masked shrew (Sorex cinereus)

Short-tailed shrews, when active, are constantly in motion and can be easily irritated. They become aggressive if confronted by other shrews or predators. I once had a captive short-tailed shrew that I was trying to photograph in a terrarium. I placed an upright log in the enclosure for it to climb up on so I could get a better picture. As I approached with the camera, the shrew spun around to face me and leapt at the camera, then scurried away out of sight. 

The short-tailed shrew has an additional distinction of being venomous. Venomous mammals are rare in nature, so this gives the short-tailed shrew a particular distinction among our local fauna. (There have been two toxins found in the saliva of this shrew: blarina toxin and soricidin.) Grooves on the outer surface of its lower incisor teeth that help inject the saliva into its prey. This venom can easily kill or immobilize the insects and worms it feeds on, but it sometimes uses the venom to help it feed on prey larger than itself and is able to subdue frogs, rodents, or even small rabbits.

Although this venom should be of concern to a mouse, bug, or frog, humans do not have much to fear. On the rare occasion that anyone would handle one of these secretive animals, the bite might burn and produce some swelling, but it is not life threatening. Interestingly, research has been conducted to investigate the use of this shrew venom in treating a number of medical conditions.

It is not unusual to find shrews lying dead on paths and in fields or woodlands. Although there are quite a few species of shrews, in our region the most common species are the short-tailed shrew and the cinereus, or masked shrew (Sorex cinereus). Just the other day, while walking along the edge of the woodland, I discovered two dead masked shrews. This is the smallest shrew species we are likely to find here, and it is also quite common. It is also insectivorus but does not have venom for subduing prey. Like hummingbirds, shrews have an incredibly high metabolism and do not live very long. In fact, much of the time they are not hunting or eating, they spend curled up asleep to conserve energy. In the case of the short-tailed shrew, however, its toxic venom probably makes it taste bad, so they are often killed but not eaten. 

A long-tailed shrew, the masked shrew (Sorex cinereus).

A long-tailed shrew, the masked shrew (Sorex cinereus) has a pointed nose and is browner in color. It averages about 3.8 inches (97 mm), nearly half of which is its tail.

If you should be observant enough on your walks through any woodland to find an owl pellet—the regurgitated fur, bones, and feathers from past meals—you can dissect it to see what the owl has been eating. Since owls have more primitive digestive systems than hawks, the bones are not digested and turn up in the pellets. Most small mammals can be identified by examining their teeth. Shrew remains are often found in the pellets and can be quickly identified by the fact that the tips of their teeth are stained a dark brown.

Shrews are fascinating and valuable components of our natural world. Since much of their diet includes larval stages of moths, they help control many of the pest species of moths such as cutworms, army worms, spruce budworms, and other caterpillar pests of forests and gardens. Next time you are out in a natural area, keep an eye and ear alert to these miniature predators.


©2017 Chicago Botanic Garden and my.chicagobotanic.org

When it comes to controlling invasive plants, a little faith can’t hurt. This is particularly true for garlic mustard (Alliaria petiolata).

We have been struggling to get this highly invasive biennial plant under control at the Chicago Botanic Garden for more than 20 years. When I first began working on restoration of our 100-acre Mary Mix McDonald Woods, it took weeks of hand-pulling with many volunteers each spring to clear just 10 or 11 acres. After years of not letting the garlic mustard set seed in the McDonald Woods, a few years ago we finally began to see a light at the end of the tunnel (though we’d still end up with mountains of pulled garlic mustard each year). Thanks to the tremendous help of Garden volunteers, garlic mustard growth in the Woods has finally been curtailed, and each year we are now able to remove all flowering garlic mustard in the Woods’ entire 100 acres.

Garden volunteers pose with a pile of removed garlic mustard at an annual "garlic mustard pull" event.

Over nearly two decades, Garden volunteers have played a critical role in helping remove garlic mustard from the McDonald Woods.

About six or seven years ago, we began a new ecological restoration project in the Barbara Brown Nature Reserve (located at the south end of the Garden near Dundee Road). The area was highly degraded and choked with buckthorn shrubs (Rhamnus cathartica). After the buckthorn was removed, the following spring was a nightmare in terms of garlic mustard. Acres upon acres of garlic mustard monoculture required removing several dump truck loads just to begin making a dent in the population.

Garlic mustard takes over after buckthorn is removed from the woods.

After buckthorn was removed from the Barbara Brown Nature Reserve, garlic mustard plants completely dominated the understory vegetation for several years.

Garlic mustard became so dense in the Brown Nature Reserve that we were reluctant to pull it, since the resulting soil disturbance would greatly enhance sprouting of the soil’s dormant garlic mustard seeds. Fortunately, one of the Garden’s creative mechanics devised a basket system on a hand-held scythe. This ingenious tool allows us to harvest the plant tops by cutting and collecting the unripe seedpods—but unlike hand-pulling, using this tool completely eliminates soil disturbance.

Although the Reserve covers only six acres, in the first few years we were not able to remove all the garlic mustard plants before they began to drop their seed. This led to several more years of hand-harvesting to get the population more under control. Fast forward to spring 2017, and we’ve only found about 75 flowering plants to remove so far. What was once viewed as an impossible goal to achieve (i.e., near-total elimination of flowering garlic mustard from the reserve) has actually happened! Too good to be true, perhaps?

A handmade garlic mustard "rake" captures unripe seed heads.

This ingenious device fabricated by one of the Garden’s maintenance mechanics allows us to capture the garlic mustard’s unripe seedheads cut by the scythe’s sharp blade (the curved metal piece along the bottom).

Even with faith as small as a mustard seed, then you can move mountains: nothing will be impossible ― Viola Shipman, The Charm Bracelet

There have been recent field observations circulating in the Chicago region regarding a possible disease that apparently is having a significant negative effect on garlic mustard (see woodsandprairie.blogspot.com).

Over the past several weeks, observers have reported an almost complete absence of garlic mustard in areas that are undergoing habitat restoration—and this absence has even been observed in areas where no invasive species management has been done. Further, some restoration workers have reported garlic mustard with very “weird” rhizomes that have many small plants emerging along them. This is not at all a normal growth form for garlic mustard. The speculation is that a virus or some other pathogen is deforming and/or killing the plants. This potential pathogen might explain why we have observed such an incredible decline of garlic mustard at the Barbara Brown Nature Reserve this spring.

I have also taken note of several roadside areas along my commute to work that in past years had dense stands of garlic mustard. This spring, I’m not seeing any garlic mustard flowers there at all. Yet quite interestingly, I’m still seeing dense stands this spring in areas outside the Chicago area. What’s going on with our region’s garlic mustard?!

The next few weeks offer a great opportunity for Garden members to check their yards and other nearby areas that in previous years had shown dense stands of flowering garlic mustard. Maybe you’ll see a dramatic decline as well. Since this seems to be a very recent phenomenon, natural resource managers will need to continue monitoring to see if the decline persists.

Wouldn’t it be great if nature offers a way to rid our region of an invasive plant that has been plaguing our natural areas for so long? Stay tuned!


©2017 Chicago Botanic Garden and my.chicagobotanic.org