Tuesday, July 12, 2011

The Small and Seldom Seen Pygmy Shrew

The vast expanses of conifer and mixed forest that exist in the Adirondacks serve as home to numerous forms of wildlife. While many of these creatures are easy to recognize and lead lives that have been well studied by researchers, others are still shrouded in mystery. Among the mammals that are difficult to identify and which have not been well researched is a tiny creature believed to be widespread across the Park – the pygmy shrew.

The pygmy shrew ranks among the smallest mammals in the world as this miniature creature has a weight of only a tenth of an ounce. This is about the same as that of a hummingbird, or a penny. However, this fuzzy beast is substantially larger than a copper coin with its body measuring about two and a half inches from the tip of its long, wedge-shaped snout to the base of its wiry tail. By comparison, this is about half the length of a mouse, and only one-eighth its weight.

While it would seem that a mammal of this incredibly small size is easy to identify, confusion exists because a related species, the masked shrew, can be nearly as small, and has almost identical external features. Only a detailed dental analysis can positively tell the pygmy shrew from an immature masked shrew.

Since very few studies involving this ultra-small mammal have ever taken place in the Adirondacks, little is known about most aspects of its life history here in the Park, as well as its current status. Almost all of the scientific information regarding the pygmy shrew’s life comes from just a handful of studies that were undertaken in Alaska, Canada and a few other locations where stands of timber exist, especially in northern regions.

Because the masked shrew forages along the forest floor, as do many other shrews, it can be collected by researchers using certain ground traps. The pygmy shrew, however, is reported to spend more of its time in narrow, crayon-diameter tunnels that exist just below the soil’s surface. This prevents the pygmy shrew from being routinely captured by conventional methods whenever surveys of small mammals are performed. Also, since a live specimen captured in a trap is nearly impossible to properly identify in the field, reliable scientific data on the abundance of this species has been a challenge for wildlife biologists to collect.

Like all shrews, the pygmy shrew feeds heavily on invertebrate matter. Spiders, grubs, worms and caterpillars are routinely harvested by this active predator as it probes the nooks and crannies on the forest floor. The pygmy shrew is believed to concentrate more of its time just below the surface in the burrows of voles, moles, earthworms and in tunnels which it makes itself as it pushes its wedges-shaped head into the spongy layer of dead matter that covers the ground. In this way, the pygmy shrew does not compete directly with the masked shrew for food, as this slightly larger species prowls more just above the soil’s surface. While both species are believed to coexist in the same location, and may occasionally utilize the same travel corridors under fallen logs, pieces of rotted bark and partially uprooted stumps, little is known about the interaction between these two species.

While there is evidence to suggest that the pygmy shrew exists in most types of northern woodlands, this creature does show a preference for stands of evergreens that are close to a source of water. The prolific presence of conifers in the Adirondacks, along with the abundance of fresh water would seem to make our wilderness a perfect retreat for the pygmy shrew; however, there is very little hard evidence to indicate that this species of shrew exists in the Park.

It is hard for some people to believe that in the 21st century there still exist creatures, like the pygmy shrew, about which we have learned very little – at what time of the year do they breed, how many litters do they have during a single year, what kind of social structure do they have, how long do they live, and how do they manage to survive northern winters? While sacked out in a sleeping bag at a campsite, there could easily be one or several pygmy shrews only an arms length away engaging in activities that are unknown to anyone.

The wilderness of the Adirondacks is a great place to explore, and there are still many facets of our environment that have yet to be examined.

Tom Kalinowski has written several books on Adirondack natural history.

Related Stories

Tom Kalinowski is an avid outdoor enthusiast who taught field biology and ecology at Saranac Lake High School for 33 years. He has written numerous articles on natural history for Adirondack Life, The Conservationist, and Adirondack Explorer magazines and a weekly nature column for the Lake Placid News. In addition, Tom’s books, An Adirondack Almanac, and his most recent work entitled Adirondack Nature Notes, focuses on various events that occur among the region’s flora and fauna during very specific times of the calendar year. He also spends time photographing wildlife. Tom’s pictures have appeared in various publications across the New York State.

Comments are closed.

Wait! Before you go:

Catch up on all your Adirondack
news, delivered weekly to your inbox