Archives For December 2017

Shrew-ed Observations

Jim Steffen —  December 12, 2017 — 2 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

Over the river and through the woods you trekked to find the perfect, most lush Christmas tree (okay, maybe you drove to the nearest retail lot and pointed at that one). Now that you picked your evergreen, how do you make it last through the holidays (and possibly even longer)?

Keeping your tree fresh isn’t hard—most can live up to a month—as long as you follow some simple rules of evergreen thumb. Get it? Horticulturist Tom Weaver explains how to get the most life out of your tree in a few easy steps.

christmas_tree_on_esplanade

Pick a fresh tree
If you’re shopping for pre-cut live trees at a nursery or retail lot, never buy a bagged tree, says Weaver. It’s harder to know whether the tree is fresh if it’s wrapped in netting. The best way to tell which pre-cut tree will last longest is to do the “shake test.” Grab a tree by its trunk and give it a little jostle. If more than handful of the tree’s needles fall off, you may want to keep looking. Also, make sure the needles are firm, flexible, and dark green—not dry, brown, and brittle. Firs keep their needles longest, but there are many kinds of evergreens to choose from.

Give the stump a fresh cut
If you purchase a tree at a location less than 20 minutes from your home, ask for the tree stump to be cut ½ to 1 inch while at the retailer. If you’re commuting more than 20 minutes with tree in tow, make the cut yourself at home. When a tree sits in a lot, its stump creates a callus to prevent it from losing water and sap. A fresh cut allows the tree to absorb water more easily. Make sure the cut is perpendicular, not at an angle or pointed.

Watering rules
As soon as you get your tree home, plunge it in a bucket of room-temperature water until you’re ready to put it in a tree stand. Make sure the tree stand reservoir can hold enough water for the size of tree you picked—Christmas trees generally drink a quart of water a day per 1 inch diameter of the tree’s stem. Most drink up to a gallon a day. Don’t let the water dish run dry!

To feed or not to feed?
Although some tree experts say water is plenty, Weaver recommends adding Christmas tree food to the mix. “Think of it as a giant cut flower,” said Weaver. “You’ll have better luck extending the life of your tree with some food.”

Step away from the heat
Though you’ll likely want to snuggle up next to the fire to gaze lovingly at your tree, the tree doesn’t share this wish. Position it far away from any heat source (fireplaces, furnaces, radiators, and heating vents), because heat speeds up the drying out process. Not only will that mean your tree will die sooner, but a dry tree is also a big fire hazard. Show your tree some love by keeping it in a cool place, and you’ll enjoy its piney scent through the New Year.


©2017 Chicago Botanic Garden and my.chicagobotanic.org

Why did five Midwestern horticulturists hike through the oak-hickory forests of the Missouri Ozarks? And why did we need a desiderata? The first question is easy—we were on the trail of specific wildflowers and woody plants to preserve and add to our collections.

Collections trip horticulturists Mike Jesiolowski, Tom Weaver, Josh Schultes, Kelly Norris, and Steve McNamara

Collections trip horticulturists Michael Jesiolowski, Tom Weaver, Josh Schultes, Kelly Norris, and Steve McNamara (left to right)

In a trip funded by the Plant Collecting Collaborative (PCC), a consortium of public gardens, Tom Weaver (horticulturist, Dwarf Conifer Garden) and I (senior horticulturist, Entrance Gardens) joined Kelly Norris (the trip leader) and Josh Schultes of the Greater Des Moines Botanical Garden, along with Steve McNamara of the Minnesota Landscape Arboretum. Before we left, our desiderata—or essential list of desirable plants we would target—was developed, based on what plants our gardens deemed important for conservation, to fill a gap in our collections, or add beauty to our display gardens. And of course, we had the proper state and federal permits in hand for seed collecting. The six areas that we explored were typically oak-hickory forests, which opened up to rocky-soiled glades and provided for plentiful opportunity for collecting wildflowers. With an eye for distinct plant material and genetic diversity, we roamed through the uneven Ozarks terrain, but we weren’t tied to our wish list—we also found a couple of surprises.

Glade opening at Roaring River State Park

Glade opening at Roaring River State Park

Since seed-grown plants are reproduced sexually through pollination, via wind or insects/animals, they are genetically variable. A variety of genes can give each plant the best chance to exhibit a specific phenotype, or physical appearance, and better adaptability to survive pests and diseases. Where seeds are collected could have significant implications on whether a plant can survive in a given environment or not. For instance, we collected seeds of Echinacea paradoxa (yellow coneflower) from its northern most growing region, in Ha Ha Tonka State Park in Missouri. Selecting seeds of Missouri provenance gives this wildflower a better chance of survival in our region, rather than if the seeds had been collected in Texas. Plants that have a different phenotype from what we commonly observe in northern Illinois were of special interest to us. Fruit from Diospyros virginiana (common persimmon) was collected on a 4-foot-tall tree in Mark Twain National Forest because it is unusual to see fruit on a tree of such short stature. In a similar fashion, Symphoricarpos orbiculatus (coralberry), was collected from the Big Buffalo Creek Conservation Area, after we all remarked at the stunning ornamental quality of the fruit display.  

Yellow coneflower (Echinacea paradoxa)

Yellow coneflower (Echinacea paradoxa)

Persimmon (Diospyros virginiana)

Persimmon (Diospyros virginiana)

Josh Schultes examines some holly (Ilex decidua) for collection.

Josh Schultes examines possumhaw holly for collection.

In some cases, we came across desirable plants, but they had already dropped their seed for the year, or simply didn’t produce any due to drought-induced stress. With the aid of GPS, we marked these areas so future explorers to the Ozarks are aware of these plants for their potential collections. For example, Boyce Tankersley, the Chicago Botanic Garden’s director of living plant documentation, was a part of a team that collected in many of these same areas in 2005; their field data was helpful in our search.

Dotted blazingstar (Liatris punctata)

Dotted blazingstar (Liatris punctata)

Although the Ozarks region experienced a late-summer drought that negatively impacted seed production in some instances, we were still able to make 71 collections from October 12 to 16. Our seeds will be grown in our plant production greenhouses. Once they achieve a certain size, they will be distributed to PCC members and planted in the Garden. I am ecstatic to cross Liatris punctata (dotted blazingstar) off the desiderata for use in my gravel garden project in parking lot 1. The seeds we collected should be ready to plant in these beds in two years.


©2017 Chicago Botanic Garden and my.chicagobotanic.org