Archives For Jim Steffen

To feed, or not to feed, that is the question:
Whether ’tis nobler in the mind to suffer
The slings and arrows of empty bird feeders,
Or to take arms against a sea of winter cold
And by opposing it, feed them.

I hope William Shakespeare doesn’t mind me modifying his famous lines a little, but you get the idea. When winter arrives, we see the birds all fluffed-up out in the cold and wind and snow and feel the need to “save them,” or at least make their lives easier. For the most part, birds are perfectly capable of dealing with the weather and finding food. Most of the birds that are not able to cope have long since migrated south for the winter. Therefore, we mainly feed birds for our own benefit. It provides an opportunity to view birds up close, watch their behavior, and have a sense of doing our part for nature. 

Common redpoll (Acanthis flammea)

Common redpoll (Acanthis flammea)

There are positive and negative things about feeding birds.

On the negative side, there is the way feeders concentrate many birds in a small area, making it easier for diseases to spread among the population. The concentration also might make them more susceptible to predation. Drawing birds closer to your home can make them susceptible to window collisions. Feeding birds can also attract unwanted animals like rats, pigeons, English sparrows, European starlings, raccoons, and house cats allowed to run outdoors.

Yellow-rumped warbler (Setophaga coronata)

Yellow-rumped warbler (Setophaga coronata)

On the positive side, some studies have shown that access to feeding stations increases winter populations of some species. More chickadees may survive a severe winter if food is provided than if they are totally on their own. (There is the question of whether it is truly a benefit to the population to have more individuals survive if some of those individuals are weak, genetically compromised, or carrying disease, but that is another matter.) 

I think the greatest benefit to feeding birds is the connection it provides between people and nature.

In a society when people have become much more distanced from nature, feeding birds is perhaps the simplest and easiest way to make that connection. This important link to nature far outweighs any negative impacts of bird feeding. For instance, one additional benefit is the opportunity to get involved in citizen science projects. The Cornell Lab of Ornithology in New York has a Feeder Watch Program that allows members of the public to collect important population data on birds visiting their yards. It is also possible to reduce negative impacts by following a few general rules. 

Pine siskin (Spinus pinus)

Pine siskin (Spinus pinus)

Downy woodpecker (Picoides pubescens)

Downy woodpecker (Picoides pubescens)

Generally, feeding birds above ground in some type of feeder is better than placing food on the ground. This will limit the number of mammals that are attracted to the feeding station. The type of feeder can limit the size and types of birds you want to feed. Tubular feeders with small (or no) perches tend to prevent large birds from accessing the food. Tubular thistle feeders have very small holes designed to provide access to the small thistle seed, limiting use to species like goldfinches, siskins, and redpolls. Applying any of a number of guards to the pole or line that supports the feeder can prevent mammals like squirrels and raccoons from getting to the feeder. If you do want to place food on the ground for ground-feeding birds like juncos and tree sparrows, place only small quantities of seed on the ground so it gets used up before the end of the day.

Robins (Turdus americanus) warming themselves on sun-heated pavement.

Robins (Turdus americanus) warm themselves on sun-heated pavement.

It is also important to think about cover for the birds. It is better to place a feeder where birds have access to some type of cover, like shrubs or evergreens. This gives them an escape route if predators—like hawks—show up. Trees and shrubs can also moderate climatic conditions around the feeder.

Keeping feeders reasonably clean is also important when it comes to reducing any disease problems that might occurs as you draw more birds to your yard. This is particularly important for tubular feeders, where birds are in much closer contact with the feeder. Washing with a weak bleach solution periodically is recommended.

What kind of food should you provide to the birds? Almost every study I have ever seen has found that the small black-oil sunflower seed is the seed preferred by the greatest variety of birds. When a seed is preferred by more species, there is less seed that gets wasted or scattered on the ground to attract unwanted birds and mammals. Although woodpeckers will also use the small sunflower seeds, they much prefer suet feeders. When shopping for suet, try to find brands that are primarily animal fat with few other ingredients like corn, millet, or milo seed.

American goldfinches (Spinus tristis) in winter plumage

American goldfinches (Spinus tristis) in winter plumage

Slate-colored dark-eyed junco (Junco hyemalis)

Slate-colored dark-eyed junco (Junco hyemalis)

Some ingredients that are beneficial are peanut pieces, hulled sunflower seed, and pieces of fruit. Generally, suet feeders do not have perches, so this limits the birds that can access the food. (One exception is the European starling that can be a problem on suet feeders. I have found that placing suet on the underside of a board allows access to woodpeckers and nuthatches, but makes it much more difficult for starlings to hang on.) Another benefit of suet is that it provides food for migrating birds that may have remained behind for various reasons. We have a yellow-rumped warbler visiting our suet feeder on a daily basis. Thistle seed is especially attractive to a variety of winter finch species. Because of its small size, it generally requires using specially designed feeders that cater to small finch species. In most cases, the cheaper brands of mixed seed often contain unpreferred seeds that serve as fillers in the mixes. It is better to avoid these, as they can produce increased waste grain that can attract unwanted guests.

Water is another good thing to provide for birds in winter. Obviously, most water sources are frozen, so it is necessary to use a bird bath heater to keep water open and available in the cold. Another nice thing about water is that it will attract birds that might not normally visit a feeding station, especially as temperatures warm up. Some people who have kept a species list for birds visiting their yards have found that their list more than doubles once water is provided.

Northern cardinal (Cardinalis cardinalis)

Northern cardinal (Cardinalis cardinalis)

One last point to keep in mind is that the appearance of birds at your feeder can change due to fluctuating weather patterns. If we experience a period of mild weather, the birds may be off finding naturally available food and not find it necessary to come to you feeder. You may experience a week or more when almost no birds show up at your feeder. This is a normal occurrence and should not be considered an indication of some environmental problem affecting the health of the local bird population.

So if you have a desire to get more involved with the birds in your yard, follow these few simple guidelines and let the enjoyment begin.

Come #birdthepreserves with the FPDCC; view the list of upcoming events for free events near you.

©2018 Chicago Botanic Garden and

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

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 ShipmanThe 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

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

With more than 1,850 known species of moths in the state of Illinois—more than ten times the diversity of butterflies—it is a real adventure sampling the moth species inhabiting the McDonald Woods at the Chicago Botanic Garden.

Using a combination of light and bait traps along with visual searches, I have been investigating the diversity of moth species found in the restored portions of our oak woodland. Moths are removed from the traps and then photographed before being released back to the woodland.

PHOTO: Ctenucha virginica (Virginia Ctenucha) moth.

The metallic scales of Ctenucha virginica (Virginia Ctenucha moth) are striking—even its wings have a metallic sheen.

My interest in moths stems from the fact that many of the species are dependent on one or just a few native plant species for their survival, and as a result, may serve as valuable indicators of the health of our recovering, once-degraded oak woodland. The larval stages—the caterpillars—primarily feed on the roots, stems, and leaves of the plants. Adult moth species are very important pollinators. White-flowered and night-fragrant plant species are often what they seek. There are day-flying moths also, like some of the hawk moths (which are often mistaken for hummingbirds) that are seen visiting a variety of flowers in full daylight. Moths are also a tremendously important part of the food chain. Entomologist Doug Tallamy tabulated the number of caterpillars that were utilized to support one nest of black-capped chickadees and found that they consumed between 6,000 and 9,000 caterpillars, most of which were moth species. Adding even a few native plant species to your yard can benefit a multitude of these valuable invertebrates.

PHOTO: Smerinthus jamaicensis (Twin-spotted sphinx moth).

Smerinthus jamaicensis (Twin-spotted sphinx moth)

PHOTO: Plusia contexta (Connected looper moth).

Plusia contexta (Connected looper moth)

PHOTO: Ponometia erastrioides (Small bird-dropping moth).

Ponometia erastrioides (Small bird-dropping moth)

PHOTO: Plagodis phlogosaria (Straight-lined Plagodis moth).

Plagodis phlogosaria (Straight-lined Plagodis moth)

It is a never-ending surprise to see what new species will show up each time traps are placed.

Some species are so small (usually referred to by lepidopterists as micromoths) that most people would pass them off as gnats or pesky flies. Some micromoths are only 3-4 millimeters long. One in particular I like to refer to as the “Nemo” moth, as in Finding Nemo. I gave this species that name because its colorful pattern reminds me of a clown fish.

PHOTO: A cryptically-colored Noctua pronuba (Large yellow underwing moth).

A cryptically colored Noctua pronuba (Large yellow underwing moth)

At the other end of the spectrum are the moth species that are quite large. The giant silkworm moths, like the luna and Cecropia moths, have a wingspan of more than 140 millimeters. Starting in mid-July and going through September, a group of medium to large moths known as underwing moths starts appearing in the woods. These delta-shaped species are usually very cryptically colored on their forewing and brightly and starkly colored on their hind wing. The cryptic forewing allows them to blend in with the tree trunks they are resting on; the hindwing only becomes visible when they spread their wings to fly. It is thought to be a distraction or scare tactic to foil predators.

Although there is a subtle nuance of shapes, colors, and textures that distinguish many species, there are also those that are in-your-face with shockingly bright colors, metallic ornamentation, stark patterns, and jagged ridges of scales—much like a mountain range on six legs—that never fail to impress me. The looper moths are one good example. Many have stigmas (distinctive white patches and scrolling) on the surface of the wing and spectacular assortments of peaks, crowns, and ridges of scales on the thorax and inner edges of the wings. The scale patterns most likely evolved to break up the silhouette of the moth to make it less visible. One of the hooded owlet moths has a tall patch of scales on its thorax that looks like a witches hat when erect, but it can also be laid down over the moths head to make it look like a broken-off stick.

PHOTO: Leucania pseudargyria (False wainscot moth).

Leucania pseudargyria (False wainscot moth)

In general, there is a new group of species that emerges about every two weeks during the year, with midsummer being the peak for species and abundance. Many moth species have relatively short flight periods and can only be seen at certain times of the year, but some have multiple broods that show up several times during the year. When I show some of these moths to colleagues, they almost always say, “I never knew these things existed.”

Under the cover of darkness, there is a world of beauty and fascination fluttering silently among the trees. It makes me wonder if the full moon doesn’t show up once a month just to shed a little light on the show, just so we don’t miss it completely.

©2016 Chicago Botanic Garden and

While working out in the woods this winter, a small lump on the branch of a young elm tree caught my attention. At first I thought it might be a gall, or an injury that had healed-over. On closer inspection, the lump turned out to be a ruby-throated hummingbird nest from last summer. 

Although I see hummingbirds regularly at the Chicago Botanic Garden, I rarely encounter one of their nests. Hummingbirds themselves are amazing, but their nests are truly a marvel of avian architecture. Not much larger in diameter than a quarter, they are just large enough to hold the one to three navy bean-sized eggs of the hummer. For the pint-sized bird to be able to keep the tiny eggs warm during incubation requires that the nest be not much larger than her body. 

PHOTO: Hummingbird nest and quarter (for scale).

Not much larger than a quarter, the ruby-throated hummingbird nest is an engineering marvel.

This is all well and good until the eggs hatch. Growing young hummingbirds can double or triple the amount of room necessary to hold the family. One of the ways the hummingbirds get around this need for flexibility is that they construct the nest of soft plant fibers and then wrap the whole thing with spiderweb silk. This creates an elastic nest that has the ability to expand as the contents of the nest increases. Can you imagine yourself going out and plucking a strand of sticky silk from a spider web with your fingers and then trying to use it to build something out of lightweight fuzzy plant fibers? I imagine you might find yourself wrapped up in a ball like some sort of oversized grotesque moth cocoon. The silk also helps to anchor the nest to the top surface of a horizontal branch.

PHOTO: Spiderweb silk is used by hummingbirds as a nest liner.

Spiderweb silk: the expandable nest liner preferred by hummingbirds.

Keeping the nest just the right size as the need arises helps to keep the growing youngsters warm and secure. In the western states where several species of hummingbirds nest, often at higher elevations, it is not only important to keep the nestlings warm, but also the incubating female, especially at night. Therefore, it is often the case that hummingbirds in these colder situations will locate their nests on a limb with an overhanging branch acting as a sort of roof to help block the nest from the night sky. 

Although this measure helps reduce heat loss, it is often the case that nesting females will go into a state of torpor (reduced physiological activity to lower body temperature) in order to conserve energy on particularly cold nights. This is a principle of physics in which the larger the difference in temperature between objects, the faster the heat flows from the warmer one to the cooler one. Therefore, a hummingbird with a lower body temperature will lose heat more slowly than the one with a warmer body. As I stated earlier, hummingbirds are amazing!

PHOTO: Parmelia sulcata, a common lichen, is used to help disguise the hummingbird's nest.

Parmelia sulcata, a common lichen, is used to help disguise the hummingbird’s nest.

Part of the reason—besides size—I had not noticed the nest earlier is that the birds do a fantastic job of camouflaging it. This also relates to the spiderweb silk. Some or all of the silk used is sticky. Upon completion of nest construction, the birds collect bits of lichen and attach them to the sticky strands on the outside of the nest. Interestingly, the birds seem to always use the same species of lichen, one that goes by the name of Parmelia sulcata

Parmelia sulcata is a light greenish-gray lichen with a leafy (foliose) appearance. One of our more common lichens, it is often seen on the upper branches of trees, and was particularly abundant on the ash trees that died from emerald ash borer. I don’t know if the birds chose this species of lichen in particular or, being common, it is just found most often. It is also interesting that the birds seem to apply the lichens to the nest in an upright position, with the top facing outward, so they look like they could be growing on the nest.

Come birding at the Garden! Take a birding class; join a group, and check your finds against our bird list.

Although this process is fascinating, it is not restricted to hummingbirds. One of the other breeding birds at the Garden utilizes a very similar nest construction technique to hold its three to five small eggs. The blue-gray gnatcatcher, another tiny bird (that somewhat resembles a miniature catbird in appearance and sound), also constructs a nest out of soft plant fibers, including spiderwebs, and applies lichen to the outside of its nest. A nest of this species, a little larger than that of a hummingbird, was found on a branch of one of the locust trees growing in a Garden parking lot.

PHOTO: A female ruby-throated hummingbird (males have the ruby coloring) enjoys a sip of salvia nectar in Circle Garden in summer.

A female ruby-throated hummingbird (males have the ruby coloring) enjoys a sip of salvia nectar in Circle Garden in summer.

PHOTO: A blue-gray gnatcatcher at the Garden; females look similar, but are less blue.

A blue-gray gnatcatcher at the Garden; females look similar, but are less blue.

If you’re lucky, you might find the nest of one of these birds during the nesting season, but if not, keep an eye out for little bumps, lumps, and knobs on bare branches in winter. You might get lucky.

Come #birdthepreserves with the Forest Preserves of Cook County. View our list of upcoming events for free events near you.

©2016 Chicago Botanic Garden and