Small Mammals at Possibility Place Nursery

December 21, 2011

Over the years we have had numerous employees, interns, clients, friends and even a couple of groupies. The amount of information, stories and studies that have come through our doors for discussion from these groups is quite staggering. We love this part of the job. I can not tell you how many times we’ve sat down with a prospective inquisitor of the natural world and shot the puck around. So to speak. Most of the time both sides come away with a better understanding of something. Then there are those times that we simply say “Huh?” We are always open to to these experiences and feel that they are crucial to a better understanding of nature. It's a big part of what we do.

A number of years ago we got to the point that all we did was assist others in the pursuit of knowledge and we thought why can’t we do that here? So we started actually tracking some of our little experiments. Most of our studies are centered around the improvement of our product and to see how our plants respond to different kinds environments. Some of them are very exacting, many are anecdotal, but all of them are informative. We encourage this kind of activity by all who work and shop here and from time to time we even have them do a write up so we can share a good idea or an interesting topic. The following is a trapping love story by one of our former interns, Laura Schwer. She outlines an often overlooked, but hugely important, part of the habitat here at the nursery. We pride ourselves on keeping as close to nature as possible and she gives a peek at part of that directive here:

Many of my fellow nature lovers seem to have so many amazing stories of observing countless numbers of magnificent animals in the wild. From spotting a bald eagle perched stoically on a branch overlooking a river bend to watching a red fox romp playfully through a flowering meadow. I, on the other hand, have always found myself looking in the exact wrong direction at the exact wrong time. Despite my amazing luck, my love of these sly creatures has never dwindled, and I pursued a college degree studying Fish and Wildlife Conservation. During my junior year, I pleasantly discovered that since these animals have decided not to present themselves to me on their own, I can now take measures into my own hands having been taught how to properly trap and handle small mammals. I instantly fell in love with small mammal trapping and the rest is history.

Small mammals play an important role in promoting healthy, balanced ecosystems by performing a variety of ecosystem services. These services include preying on insects, consuming and dispersing seed, cycling nutrients, improving soil structure by constructing burrows, and most importantly by being a vital food source for many predatory birds, reptiles, and other mammals. Some of these animals have developed a “bad rap” in and around homes and on farms. However, research has shown that in most cases small mammals are actually more beneficial than harmful in crop fields due to the ecosystem services they provide. Small mammals, particularly mice species, have been known to cause damage in open grain storages and in buildings. In most cases, the culprit to blame is the house mouse, Mus musculus, an invasive species originally from Asia that is now common and abundant worldwide. You can even see them at your local pet store!

One strategy to prevent small mammal damage is implementing sustainable management practices that encourage a diverse environment. Increasing habitat diversity and minimizing disturbance increases the number of niches available for wildlife, thus increasing the diversity of wildlife that inhabits the area. You may be thinking… how does increasing wildlife diversity actually decrease your risk of wildlife damage? Increasing diversity allows a balance between predator and prey populations. Prey populations, small mammals in this case, are kept “in check” when predators are present, and thus decreases your risk of damage. When predators are absent, prey populations can sky-rocket and cause plant and property damage. This is also true with insect populations. Diverse, minimally disturbed environments are great habitats for both beneficial and potentially nuisance insects. Beneficial insects prey on the nuisance insects decreasing the risk of plant damage.

Possibility Place Nursery has kept this concept in mind from the very beginning and has developed their management strategies around this concept. For instance, Possibility Place Nursery has not used insecticide, miticide, or fungicide sprays for the past 15 years, which can all negatively affect insect, small mammal, and other wildlife populations. To confirm that Possibility Place Nursery’s management strategies are allowing greater wildlife diversity, we have been investigating the wildlife populations throughout the nursery (which is where my small mammal trapping expertise comes into play!).

During August and September of 2011, I set Sherman Live Traps at strategic locations throughout the nursery to determine what small mammal species are present. To my great pleasure, I trapped five small mammal species and a larger, unexpected capture. During one August morning, I was checking the traps set in a row of trees near one of the nursery ponds. As usual, one of the traps had a closed door signifying a successful night. As I approached the trap, I heard a noise louder than a typical mouse squeak and my curiosity grew. As soon as I picked up the trap, I knew this was no ordinary mouse as the trap weighed at least a pound and gave off a pungent odor. Cautiously, (trying to avoid being sprayed by a skunk!) I peaked inside the trap to see what was inside. To my relief, I saw a bare tail through the small crack, which in my experience means a baby opossum’s curiosity got the better of itself. I did not feel rushed to ready my camera, since opossums are slow to run and typically crouch in place hissing at my “fearsome” self. I found a stick and cautiously unlock the back door to release the captive. Awestricken, I watched as a small mink slowly poked its head out of the semi-opened trap door to see if the coast was clear. Thoughts rushed through my mind—“HOLY COW!”—“That’s no opossum!”—“Get the camera?!?”—“Close the door?!?” Meanwhile, after standing frozen in time, I finally grabbed my camera, prepared to take a picture, pressed down on the trigger … and the mink quickly scurried two feet out of the trap, stopped, looked around, and promptly spun 180 degrees and dashed right towards me… of course being my fearless, outdoorsy self I took my amazing award-winning photo of my surprise visitor… …Unfortunately, I snapped the photo at the exact time the mink decided to run directly at me, which (now with illustrated proof!) shows that I am not as fearless as I may seem to be. (For the record, minks do not have hairless tails. I was just fortunate to see the exact half inch of tail that must have gotten caught in the trap door and removed the hair.)

The American Mink (Mustela vison) are predators that feed on small to medium-sized mammals, crayfish, frogs, snakes, and birds. They inhabit areas near water that usually have wooded areas nearby, which perfectly describes the habitat I trapped the mink at Possibility Place Nursery. Another predator that I captured was the northern short-tailed shrew (Blarina brevicauda). Northern short-tailed shrews primarily consume insects, worms, snails, sowbugs, centipedes, millipedes, spiders, and other invertebrates, but they will also consume salamanders, ground-nesting birds, and mice with the help of their poisonous saliva that subdues larger prey. Seeds, fruits, roots, nuts, and acorns also make up a fraction of their diet. Northern short-tailed shrews inhabit hardwood and pine forests, borders of ponds, grasslands, brush land, fencerows, weed fields, and dense pasture. They prefer moist areas with dense vegetation and a deep litter layer in order to construct elaborate runways and burrow systems to safely navigate the habitat in search of food.

The less ferocious small mammals captured were the meadow vole (Microtus pennsylvanicus), white-footed mouse (Peromyscus leucopus), prairie deer mouse (Peromyscus maniculatus), and house mouse (Mus musculus). Meadow voles are herbivores that eat a variety of plant material, bark, roots, tubers, and seeds. Meadow voles inhabit roadside ditches, fencerows, damp meadows, orchards, prairies, and other habitats with dense vegetation. Meadow voles also construct runways used for protection from predators and safe access to food. White-footed mice are opportunistic omnivores consuming a variety of foods including insects, seeds, nuts, fruit, and green vegetation. White-footed mice do not construct runways, but move in a ricochetal pattern with short hops and constant change of direction. White-footed mice occupy a variety of habitats, including deciduous and mixed forests, hedgerows, brushy areas, croplands, and residential buildings in wooded areas. They prefer habitats with vertical diversity, like wooded areas, that allows easy access to travel on and off the ground. Prairie deer mice are also opportunistic omnivores that forage on the ground and consume mainly seeds, insects, fruit, and subterranean fungi. Prairie deer mice do not rely on herbaceous ground cover for protection, but rather construct extensive burrow systems to seek cover. Unlike white-footed mice, prairie deer mice are mainly terrestrial, running and hopping across the ground instead of climbing. Prairie deer mice are considered habitat generalists occupying a variety of habitats, like croplands, grasslands, weed fields, and fence rows. House mice, mentioned previously, is an introduced species originally from Asia that is now widespread and abundant around the world. House mice are opportunistic species that take advantage of any resource available. They consume grain, seeds, corn, wheat, soybeans, insects, anthropogenic products, and basically anything they can find. They occupy disturbed areas, such as croplands, roadsides, and buildings, and tend to avoid less disturbed habitats, like grasslands and woodlands. They are mainly terrestrial, but they will climb if necessary.

Population abundance patterns vary among the different species. Prairie deer mice and white-footed mice populations exhibit seasonal fluctuations, while meadow voles undergo seasonal and multi-year population cycles. Mice populations are low in the spring and steadily increase during the summer with peak population abundance in the fall. The fluctuations are caused by the differences between birth and death rates. Vole populations experience a cyclical abundance pattern with some seasonal changes similar to mice populations. Vole populations peak every two to five years followed by a population crash. Northern short-tailed shrew populations do not undergo predictable fluctuation patterns, but remain at low, uniform numbers year long.

The diversity of mammal species captured at Possibility Place Nursery demonstrates that the management decisions they have taken in order to create a healthy and balanced ecosystem has been successful. Even though the specific population numbers are not known as a result of this study, the presence of multiple predator and prey species inhabiting the area shows that Possibility Place Nursery has successfully created an environment that is diverse and rich in resources allowing granivores, herbivores, omnivores, and carnivores to all occupy and communally live in the same location.