Today is National Migratory Bird Day, set smack dab in the middle of May—the month to look for warblers, vireos, thrushes, sparrows, and some shorebirds, as they migrate through the Chicago area.
Most birders might agree that the highlight this time of year is warblers. It is for me—they are tiny jewels with wings. I feel totally blessed if I can see a few during migration.
Since these birds are so small, they usually wait for favorable winds to help them travel. Any night with southerly winds will have the birds moving; new birds arrive while others depart. Every year is different, so it pays to watch the weather report if you want to see these beauties while they are passing through. The good news is that there are a few warblers that actually nest in our area, so if you miss them during migration you can often find the nesting birds later in the summer.
A great place to look for warblers, like this palm warbler (Setophaga palmarum), is in all the willow trees around the Garden.
A less common warbler is this beautiful Cape May warbler (Setophaga tigrina).
I found this guy, you guessed it, in a pine tree. (He’s a pine warbler, Setophaga pinus.)
A yellow warbler (Setophaga petechia) looks for insects. These golden birds actually nest at the Garden.
Knowing when they arrive is only half the challenge. Where they will land is the second part. I’ve been surprised on many occasions to find warblers in very public places. If there is a tree, some green, or water, you have a chance at spotting a warbler. If you see a tiny bird, quickly darting in and out of a tree, there is a good chance you have found a warbler. Oaks and willow trees are particular favorites.
The birds need a food supply along the way to fuel their journey. Most of them are insect eaters, and some supplement their diet with seeds and nectar from flowers. While the cold spring delayed the plants a bit, the insects come out as soon as it is above freezing and you can see the birds darting around eating as many as they can. If you want to attract warblers to your yard, plant native trees and shrubs in your yard and be sure to add a shallow water dish.
Here you can see how this warbler got its name. The yellow-rumped warbler (Setophaga coronata) is one of the most common warblers you will see here.
A very understated orange-crowned warbler (Vermivora celata) keeps an eye on me.
Black-and-white warblers (Mniotilta varia) can be found hopping up and down the bark of trees looking for insects.
Migrating birds are one of nature’s greatest wonders. Different birds migrate at different times of the year, but all told, millions of birds make the trip north and south each year, navigating all sorts of hazards along the way. I am in awe of these tiny birds that travel so many miles. They are the elite athletes of the avian world.
The cooler than average spring did allow a few loons to stay longer than usual around the Garden. It was really fun seeing them stealthily appear from seemingly out of nowhere. A major rarity showed up for just one day, a white-faced ibis. I was lucky to be around to see it; a first for me, and I believe the Garden as well.
Wow, what a treat! I’ve never seen this bird before. White-faced ibis (Plegadis chihi) is a very rare visitor to the area.
The first wave of warblers arrived early in May and many from that group have moved on, although you can still see palm, yellow-rumped, black-and-white, and Nashville warblers at the Garden now. There should be several more waves before the month is over, as well as a few interesting sparrows and vireos. Warblers migrate at slightly different times. There are those that show up at the end of April and early May, those that you will see mid-month, and a few late ones that show up at the very end of the month. I like to go out every day in May, just in case a new wave of warblers has shown up, I hope you will too!
The warbling vireo (Vireo gilvus)—not a warbler, but its song sounds like one.
Join me and #birdthepreserves this month. My top five migration places to visit in the spring are the Chicago Botanic Garden, Montrose Point Bird Sanctuary (the magic hedge) in Chicago, The Grove in Glenview, LaBagh Woods in Chicago, and Ryerson Woods in Deerfield.
“The wonder of the world, the beauty and the power, the shapes of things, their colours, lights and shades—these I saw. Look ye also while life lasts.” —Anonymous lines found on an old tombstone in Cumberland, England
“While life lasts.” This can be a very brief moment in time for a spring ephemeral. In that narrow window that exists between thawing ground and the leafing out of the tree canopy, spring ephemerals—those woodland wildflowers that emerge, then quickly go dormant—live their life.
White trout lilies (Erythronium albidum)
If you want to see some of the spring woodland flowers in bloom, you often have to be there on the day. In the McDonald Woods at the Chicago Botanic Garden, sometimes all you find are petals scattered on the ground, and you realize you have to wait another year. This is particularly true of species like bloodroot (Sanguinaria canadensis), whose blossoms only last for a day before they drop. Additionally frustrating is that cloud cover can hamper catching the full glory of the blooming of some species. You may show up on a sunny morning only to have the blossoms close up before your eyes. Species like spring beauties (Claytonia virginica) will only open in the full sun and will close again if clouds appear. This response to sunlight may be the result of temperature or light. Some ephemerals might provide longer viewing opportunities, since they hold their flowers for a longer period of time, or have many more plants that flower on different days.
Most of the spring ephemerals are perennial. They have underground organs—bulbs, corymbs, etc.—that store nutrients to be used for producing leaves and flowers in succeeding year. White trout lilies (Erythronium albidum) are a good example. The trout lilies, both white and yellow species, derive one of their common names from the mottled leaves that some think resemble the markings on a trout. (Other common names include adder’s tongue and dog-toothed violet—the second name is curious because these are plants in the lily family, having no relationship to violets.)
Trout lilies also spread by underground rhizomes that form clumps, often covering large patches in the woodland, the mottled leaves camouflaging their abundance, only to become dazzling drifts of white when the sun appears. If you have time, you can come out to the woodland early in the morning and watch the white petals of the trout lilies curl back and expose their yellow anthers to the sun—and pollinators.
There are also a few annual spring ephemerals. False mermaid (Floerkea proserpinacoides) is a spring ephemeral annual. Unlike many of the other ephemerals, false mermaid is inconspicuous in that it is a small, ferny green plant with tiny greenish flowers. Portions of the nature trail in the McDonald Woods are surrounded with acres of this species in spring. Even in these large numbers, without close inspection, it is difficult to tell when they are in flower. This species is dependent on its flowers producing one to three large seeds to be able to reproduce itself after the plant turns yellow and dies.
Many of the spring ephemerals depend on native bees for their pollination.
The trout lilies are visited by an oligolectic bee (Andrena erythronii). “Oligolectic” means this is a bee that has a narrow, specialized pollen preference, typically for the pollen of a single genus of plants. The species name of this bee, erythronii, refers to the genus of the trout lily, Erythronium. Another ephemeral with an oligolectic bee pollinator is the spring beauty. The bee that is a specialist of this ephemeral, with its attractive pink-striped flowers, is Andreana erigeniae.
While these plants often have specialist pollinators associated with them, they usually have several different pollinators that can visit, including other native bees and many species of flies.
For ephemerals in the genus Dicentra, such as Dutchman’s breeches and squirrel corn (Dicentra canadensis), queen bumblebees are an important pollinator. These ephemerals have tightly closed flowers, requiring significant strength to enter the flower and access the pollen and nectar. The large queen bumblebees are among the few pollinators equipped to gain access. This is not only important for the plants, it is also important for the bumblebees. Many native bees colonies die off in fall, leaving the queens to overwinter and start the new colonies in spring. These large, fuzzy bees are able to manufacture enough physiological heat, by vibrating their wing muscles and restricting their blood flow in the thorax, to get themselves flying early in spring before it’s warm enough for many other pollinators to go foraging for resources to start the new colonies. The spring ephemerals provide this important resource.
Besides being important sources of nectar and pollen for native insects, the spring ephemerals also serve the purpose of saving soil and reducing water runoff during a time of year when few other plants are growing.
Trout lilies, for example, have very efficient photosynthetic abilities and take advantage of the high light levels available in the spring woodland. This strong photosynthetic response requires large quantities of water to maintain the process. Therefore, abundant populations of this species and other ephemerals absorb large quantities of water that would otherwise move off site, often carrying valuable nutrients and soil with it. This high demand for moisture also causes the ephemerals to have shorter flowering periods in times of drought. In your yard, you can encourage ephemerals to flower longer during dry conditions by providing a little extra water. There is also some thought that the rapidly decomposing foliage of these “short-lived” plants provides readily available nutrients for other plants that begin growing later in the season.
One other fascinating thing about spring ephemerals is that essentially all of them rely on ants to disperse their seeds. This relationship is referred to as myrmecochory—”myrmex” being the Greek word for ant.
Each seed of the spring ephemerals has a structure called an elaiosome attached to its surface that attracts ants. The elaiosome is rich in lipids and proteins. The ants take the seeds back to their nests and consume the elaiosome as food, after which they bring the seed to the surface and deposit it on their trash piles, where the seeds tend to germinate in a rich, organic seedbed.
I include another plant with elaiosomes in the list of spring ephemerals. This is parasol sedge (Carex umbellata). This grass-like, early-flowering sedge produces most of its seeds very close to the soil surface, where ants are more likely to find them. It is not uncommon to find ants nesting at the base of these plants. I often get questions from people who have planted ephemerals in their yard, but say they don’t see seedlings, while their neighbors are finding them on their property. It is more than likely that the neighbors have the ant colony that is harvesting the seed and sowing them at the neighbors’.
Parasol sedge (Carex umbellata)
Given that the spring ephemerals are adapted to growing in a cool, moist environment and highly dependent on early spring pollinators, climate change is likely to cause stress in the system. Early warming and possibly drought conditions in spring may disrupt pollinator interactions or shorten flowering periods, making seed production more difficult, or reducing the amount of time ephemerals have for storing nutrients for future flowering.
False rue anemone (Isopyrum biternatum)
With spring on the horizon, you should make plans to visit the McDonald Woods to view the diversity of colorful spring wildflowers. For those of you taking pictures, pay attention to weather forecasts, and be mindful of the potential to damage other vegetation while attempting to get the perfect shot.
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)
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)
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)
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) 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
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)
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.
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).
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.
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)
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) 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.
The harbinger of fall, for many folks, is when asters finally bloom. Their flowers look like miniature daisies and come in shades of purple, blue, white, and occasionally pink. These cool tones allow autumnal hues of yellow, orange, and red to truly pop throughout the landscape. Aster blossoms twinkle across roadsides, meadows, woodland edges, and even home gardens. Interestingly, astéri is the Greek word for star.
White wood aster among birch trunks near the Bernice E. Lavin Plant Evaluation Garden sets the perfect fall scene.
Hosts of pollinators favor asters. The late-season blooms provide vital sustenance for adult monarch butterflies during their annual migration to Mexico. Each flower contains plentiful sources of pollen and nectar, because the central disc is comprised of up to 300 tiny florets. After pollination, a disc will turn darker and reddish, informing other insects to keep moving. In the end, birds come to consume the seeds.
Asters belong to a huge family called Asteraceae, which also includes daisies, black-eyed Susans, and sunflowers. They are mainly native to North America and Eurasia. More than 600 species once made up the genus known as Aster. However, in the 1990s, taxonomists decided to divide New World species into ten other genera. The most common ones are Eurybia and Symphyotrichum. Few nurseries adopt these names and continue to list their plants under the genus Aster.
Asters are easy to please with well-drained soil and adequate sunlight. Some even prefer shade. An assortment of heights (1 – 6 feet tall) allows them to shine in the front, middle, or back of the border. Powdery mildew is problematic for some, but you can always hide the unsightly lower stems among grasses or ferns. While pretty in nature, some asters just look scruffy in the garden. Selecting the right type is the key to a tidy look. The following asters perform best:
Jindai Tatarian aster (Aster tataricus ‘Jindai’) can be found in the Lakeside Garden and on Evening Island at the Trellis Bridge.
White wood aster (Eurybia divaricata) can be found in the Heritage Garden beds, throughout the Landscape and Bulb Gardens, in large groupings on Evening Island, and all around the Plant Science Center.
Jindai Tatarian aster (Aster tataricus ‘Jindai’) originates in Asia and has uniquely large and toothed foliage. From mid- to late fall, lavender-blue daisies appear in showy flat-topped clusters upon 3 – 4 foot tall stems. Best planted in the back of a bed with plenty of sun and space, its roots slowly spread into a weed smothering ground cover. Pair it with some equally tall and tough switchgrass (Panicum virgatum).
White wood aster (Eurybia divaricata) blooms for a long time, starting in late summer and lasting throughout fall. Clouds of starry white flowers are borne on 2-foot stems with heart-shaped leaves. It grows in woodlands of eastern North America where it spreads slowly by rhizomes and quickly from seed. Cut spent flower stems off if you do not want extra plants. Combines wonderfully with ferns, sedges, and shade-loving goldenrods like Solidago caesia or Solidago flexicaulis.
Avondale blue wood aster (Symphyotrichum cordifolium ‘Avondale’) can be found on Evening Island, just west of the carillon along the path.
Find aromatic aster (Symphyotrichum oblongifolium ‘October Skies’) in the Landscape Garden, along the Lakeside Garden path, at McGinley Pavilion, on Evening Island near the Arch Bridge, and near the Plant Science Center.
Avondale blue wood aster (Symphyotrichum cordifolium ‘Avondale’) is an extra-floriferous selection of an eastern North American species found at forest edges. A plethora of attractive blue flowers begin in early fall on 2 – 3 foot stems. Grows well in either sun or shade, where it adds additional color to perennials like Japanese anemone (Anemone hupehensis), monkshood (Aconitum), and the yellow fall foliage of blue star (Amsonia hubrichtii).
October Skies aromatic aster (Symphyotrichum oblongifolium ‘October Skies’) is a great alternative to New England aster (S. novae-angliae), because it is less prone to powdery mildew. With full sun, it forms a compact 2- x 2-foot mound of nicely scented foliage. In autumn, hundreds of blue-purple flowers cover the plant. The species naturally occurs across the central and eastern United States. Try it with fountain grass (Pennisetumalopecuroides).
Frost aster (Symphyotrichum pilosum) overflows the center plantings of the Heritage Garden.
Frost aster, or hairy aster (Symphyotrichum pilosum)is a 3- x 3-foot, clump-forming plant with many branched and arching stems. In fall, it becomes loaded with little white daisies and creates a baby’s breath appearance among flowers like Japanese anemone (Anemone hupehensis). Frost aster is common in a variety of dry, sunny habitats in eastern North America. It spreads happily by seed, so if you have too many, cut off the spent flower stems before they develop any further.