Voles, Moles and Shrews, Oh what shall I do!

At least we can say the March came in like a lion… However, I am still finding it very hard to believe that the worst of our New England winter is over. I know what you are going to say, “What winter?” In my lifetime I cannot remember having this little snow and such warm sunny days. The lack of snow this winter, however, has definitely put a crimp in my winter tracking activities. It has also provided a little bit more of a challenge, and well, challenge can be fun! That said I am looking forward to some winter tracking this weekend!

A wintery day on Beaver Brook Meadow

A couple of weeks ago I went on a “varmint” hunt. Given the lack of snow and some spring “melt,” if you can call it that, I figured I had a fairly good chance of finding sign of some ground-burrowing critters. I started by looking under hanging garden plants and turning over boards or other fixed objects in our back yard. Bingo!

What did I find?   Shrews!   Shrews have been called a lot of things but I think that Sudbury Valley Trustees described them best as “tiny tigers.” They have sharp, spike-like teeth and as the smallest mammal no bigger than our thumb (2 to 4 inches), these creatures spend most of their time running around in above-surface tunnels hunting a variety of bugs and earthworms. They will also eat other shrews, mice, salamanders, snakes and have even been known to kill small rabbits! They may also eat mast, seeds or eggs. Shrews will even cover their “kill” with grass or leaves for a later meal (just like my cats try to do with their food bowls). The shrew does not have grinding teeth and the tips of their teeth have a yellowish color when living, at least in New England.

Skull of a Short-tailed Shrew
Northern Short-tailed Shrew

Their size often allows them to escape our attention even though they are fairly common. They, like other ground-dwelling varmints such as mice, voles and moles are considerably active throughout the winter.

New England Vole

How do you know if you have shrews, rather than one of the other rodents? That is, other than seeing them. Shrews, being the smallest mammal also make the smallest hole (1 inch or less). They do not make meandering ridges just under the surface of the ground under snow like voles or moles or create 6 inch round entrance mounds like moles. If I were to catch one, I would find that each front foot of a shrew has 5 toes, where a mouse would only have 4 front toes.

Shew runway along the base of my garden wall

Behaviorally, shrews and voles are much alike. They both make tunnels or pathways in the grass and these runways can be difficult to discern from each other, especially since they will use another animals’ highway complex.

Traditional Shrew Runway in one of my back gardens

The difference is often the size. Shrew pathways which can be located in grass or leaf litter are usually less than an inch in diameter, whereas vole tunnels are slightly larger and usually only in grass. They also landscape their tunnels differently. Voles nip or cut the vegetation on the sides and bottom of their tunnels, sometimes leaving only bare earth. Shrews are less fastidious and the grass will often just be plowed to the side.

Interestingly, shrews are known to have a putrid, musky odor that makes them unpalatable to predators, so usually the only time they are found is after they have met their fate and been abandoned. BTW this is how I knew I had a good chance of finding them in my back yard… Either the fox or a neighborhood cat had clued me in. It is generally believed that the odor is a reproductive marker as it appears stronger during mating. Some shrews that we will find here in Massachusetts include the short-tailed shrew (Blarina brevicauda), least shrew (Cryptotis parva) and the masked shrew (Sorex cinereus).

Shrews are unusual among mammals in a number of respects. They are one of only two land mammals known to echolocate (the other is a mammal from Madagascar that resembles a hedgehog). Unlike most mammals, however, some species of shrew are venomous. Shrew venom is not conducted into the wound by fangs, but by grooves in the teeth. The venom contains various compounds, and the contents of the venom glands of the American short-tailed shrew are sufficient to kill 200 mice if delivered by intravenous injection. Don’t worry though, it won’t kill a human, but it may cause some swelling. Always best not to handle a live shrew without some protection. Just in case you were thinking about going homicidal on your backyard shrews, think again. Like every other living thing on the planet there is always hidden utility. Shrew venom has potential medical use, as one chemical extracted from shrew venom has been demonstrated to show potential for the treatment of blood pressure. Another compound may be useful in the treatment of some neuromuscular diseases and migraines. The saliva of the Northern Short-tailed Shrew (Blarina brevicauda) contains the peptide soricidin and has accordingly been studied for use in treating ovarian cancer. Another interesting factoid…Amazingly, shrews hold nearly 10% of their mass in their brain, which is the highest brain to body mass ratio of all animals (humans included!)

Star Nose Mole often found near wetland areas

Now moles,on the other hand, are just plain funky! The most common foods moles eat include earthworms, insect larva and other soil arthropods. They also eat grubs and plant bulbs but not as voraciously as the vole does. Most mole damage is caused by tunneling in our monotypic lawn, and not by eating plants. Go Moles!!! The most commonly encountered moles are the eastern mole, which causes most of the damage found in yards, and the star-nosed mole, which is mostly found digging tunnels in swampy areas and at deeper levels than the eastern mole. Mole feeding tunnels are usually 2 to 3 inches below the surface.

Mole

Okay, right about now you are thinking that I am absolutely insane because I am happy that I have rodents! Probably true. If they were in my house I would be at Agway right now looking at all kinds of unique ways to remove them from my abode. But what their presence in my yard, and especially in my garden, tells me is that my organic gardening practices are working. I attempt to provide a variety of plants for a variety of native insects. I do not use chemicals or fertilizer formulations other than compost tea or a nature-based organic nutrient source. I leave my leaves and plant structure throughout the winter to provide overwintering area and a food source for the critters. The presence of the shrew means that my garden is beginning to function as a miniature ecosystem with a natural balance of both predator and prey, which on a cold snowy day makes me smile.

Portrait of the Oak

It’s been a while since my last post which I will write off to the “holiday hustle and bustle.” In actuality, this entry was started the day before the October snow storm which left our household with no power for an entire week. Yes, I know that is three months earlier! That, followed by getting ready for the holidays, I just couldn’t seem to get back to things as intended (we won’t even go into that I spent most of my Christmas holiday break in bed!). Hopefully, now that the holidays are behind me I can get back to a more frequent (at least monthly) writing and posting schedule.

This time of year, I often find myself thinking about northeastern forests and their benefit to wildlife. One of the reasons for this is because all of the colorful broad leaf deciduous (BLD) trees such as maple and birch have dropped their leaves, leaving the oak (and sometimes the pole-size beech trees) as the only real frequent non-coniferous contributor to color in the landscape. During the growing season the oak is usually easily over-looked. The reason it has a tendency to stand out is that it will generally hold onto its leaves much longer, often until spring. Oaks are easily identified by the common russet brown color which is a result of a natural organic compound called tannin. Once chlorophyll production ceases in the late fall, the dominance of tannin results in the characteristic brown color.  The remnant coloration makes it easy to discern this tree and also provides a great opportunity for one to learn it’s branching structure and form and to recognize its preferred habitat.

Now, don’t get me wrong most oaks (Quercus spp.) are still considered largely deciduous and do drop their leaves (which is called abscission by the way) – they just do it later. This condition of retaining dead leaves through the winter months is known as marcescence and the reason for it is commonly debated. Physiologically speaking the leaves are retained because the base of the petiole (how many of you remember your grade school botany?) retains living tissue throughout the winter. Michael Snyder, a Chittenden VT County Forester, provides an excellent summary of the varied hypotheses for the possible benefits of  marcescence in his Northern Woodlands “Woods Wise” column. Some of the theories he highlights include colonizing adaption for nutrient poor sites; a “pulse” of nutrients and mulch for the soil when it is needed most, in the spring rather than in the fall; a physical adaption to trap snow, and therefore moisture, for the root system; a way to insulate buds and new twigs over the winter from drying winter winds or to protect them from animal browse, especially voracious moose and deer. These all seem realistic and have some basis in rational scientific documentation.  Others I have heard include the relationship between acorn/nut production, both from an ecological habitat perspective (camouflage roosting/foraging for birds and small mammals) and that of species propagation. These last two appear to be somewhat common-sense driven but anecdotal so in the end the take home message is we just don’t know.

Oaks are a member of the beech tree Family (Fagaceae) and are long-lived trees. Five-hundress years is somewhat common in northern old-growth forests. In their initial years of life they will grow very slowly. I have seen oak seedlings completely browsed to nothing for several years in a row. A mature oak will produce its first good seed crop when it is 40-50 years old (imagine if we had to wait until we were that old to reproduce…) and annual acorn production varies, with trees sometimes producing very few in a given year. Large numbers of acorns are produced intermittently in what are known as “mast years,” often at intervals of three to five years.

Oak Mast aka Acorns

Especially in colder climes mammals that do not hibernate will rely on mast-producing trees as a source of necessary protein. Great, wildlife need nuts, but what does that have to do with us? It is important to recognize that the cyclic nature of mast production affects not just wildlife but the entire ecological system and every critter in it. As recently pointed out in a December 3, 2011 New York Times article the obvious shortage of acorns during the coldest winter months could result in severe population-level losses of small rodents and other mammals  which are commonly host to Lyme Disease carrying ticks. A reduction in host organisms will leave these blood-sucking insects looking for an alternate source of food (namely us).

Adult Deer Tick

This is just another example of how every living creature in the natural environment (us included) is intricately linked.

If you would ask me or any other biologist what the best tree species to plant for overall wildlife habitat purposes is, the answer you will likely get 9 out of 10 times is Oak. But why is that? One of the key aspects of any habitat management regime is to provide a healthy diversity of resources, including trees, so why do so many biologists and ecologists weigh in so heavily for one type of tree? (Hang onto this thought as it is likely that a future posting will revisit this when I discuss Forestry Management.) One critical reason is documented by a favorite researcher of mine, University of Delaware’s Doug Tallamy. It is the oak’s ecological contribution when it comes to supporting insect herbivores such as moths and butterflies (Lepidoptera). These winged creatures are the base of the food chain and are therefore critical for maintaining a healthy diversity of wildlife. In my eyes it’s the “best bang for the buck” approach. His research has demonstrated that the number one ranking woody host plant is, you guessed it, the oak (Genus Quercus). This tree alone provides host insect habitat for 532 species of native insects.

Oak Gall (egg case)

The next closest host is the Genus Prunus (cherry, chokecherry, plum, peach) which is documented to support 456 native insect species.

Welcome to Turtles Crossing

It is  summer in the northern hemisphere and I, like the turtles, am basking in the bright glow of the sun’s warm rays. As I move wheelbarrow after wheelbarrow of compost and wood chips from one side of my deceptively large yard to the other, I try to focus on my overarching vision and forget the rivulets of sweat rolling down my neck and back and the endless buzzing sound of mosquitoes in my ears. I am busy expanding my continuously growing hummingbird and pollinator gardens. You see, the outdoors and everything within it are a passion of mine. Another of my interests is learning, so whenever I can combine this with something dear to me it is a real treat! I so envy educators because they always seem to find the best way to share their enthusiasm and what they know with other people in a fun and informative way. I often find it is easier said than done…

So with the lazy days of summer almost a memory, it seems like a great time for the birth of this blog. What you don’t know is that anyone who knows me fairly well is laughing their #@%! off right now, because there is usually not more than a few minutes to spare in my overly booked day to add something like a blog (oh, did I also say I was technologically illiterate and have no idea how to “create” a blog?). Well, just add blog author to the existing list of full-time mom, wife, environmental professional, church and community volunteer, and whenever I have a free-moment gardener for wildlife. That said, the objective of this effort is to be a creative outlet for me with which I can share the wonders of the natural environment with anyone who will listen and, hopefully, develop a friendly and informational forum both locally and regionally on gardening for wildlife and suburban conservation.