The Biting of the Shrew

I felt a sting on the tip of my finger and at first I could not figure out what had poked, bitten or stung me. Closer inspection revealed a small silvery mammal racing around the bottom of the  drift fence bucket ( a pitfall trap used for animal surveys). I quickly realized that a shrew had latched on to me, presumably to protect itself. It took a minute to sink in; I had actually been bitten by one of only a couple of venomous mammals in the whole world. My finger turned red on the end and ached mildly for a few days but it was totally worth it!

Many people don’t realize that our yards and woods are home to miniscule venomous mammals called shrews. Shrews belong to a family of small mammals called insectivores. This large family also includes moles and hedgehogs. One member of the shrew family, the Etruscan shrew, has the distinction of being the world’s smallest mammal. It weighs only about two grams (less than a penny). The much larger short-tailed shrew (about half the size of a mouse) is a common resident of vacant lots and wooded areas in the lowcountry. There is a good chance that your cat or dog has excavated a shrew tunnel and left the carcass on your doorstep. Shrews secrete a musky odor and apparently have a foul taste so they are often killed but rarely eaten by domestic pets.

Don’t let the short-tailed shrew’s small size fool you. These tiny insectivores are voracious predators, attacking animals much larger than themselves and subduing them with toxic saliva. Venom is the shrew’s meal ticket, allowing it to immobilize insects, worms, frogs, salamanders and small mammals for eating. Shrews often find food using echolocation, a similar system to that used by bats. They send out a series of clicks and chirps through underground tunnels and listen for returning echoes that allow them to differentiate between food and non-edible material. Some shrews will capture and ingest two to three times their body weight in a single day. Shrews owe their insatiable appetites to their spectacular metabolisms. A short-tailed shrew’s resting heart rate can be 800 beats per minute and a relaxing shrew may breathe 168 times in 60 seconds. Shrews often prepare for lean times by caching a selection of snails, worms and beetles and even small snakes to insure ample food supplies for the winter.

Short-tailed shrews mate in any season and females often have three or more litters of 5-7 pups per year. The young shrews are weaned and leave the nest within a month of birth. They may live as long as three years but usually don’t survive past the first. Shrews are intolerant of each other, except during breeding, and will fight and even kill each other in territorial disputes.

Because shrews are very abundant and eat large quantities of invertebrates they are considered beneficial. They feed on a variety of harmful insect species like mole crickets and other pests. It is very unlikely that a person would be harmed by a shrew unless they tried to pick it up. So, while it was pretty silly for me to put my hand in a pitfall trap before looking inside, I feel kind of lucky to have been bitten by the only venomous mammal in this hemisphere.

-tony

I never claimed to be a bat expert, but when I was called one afternoon to check out a large colony from a nearby residence, I jumped at the opportunity.  I mean, how often does one get to go play with a bunch of bats?  My oldest son (nine at that time) begrudgingly agreed to accompany me on yet another escapade. Marshall was well aware that I was a "snake guy" not a "bat guy" and expressed some misgivings about our involvement in the project. The homeowner didn't want to hurt the bats, but they were making a bit of a mess on the eaves of her house and in the attic.  After assessing the situation (40-50 bats lining a small section of the attic wall), we formulated our plan and raced back to the house for supplies.  It was easy: pluck the bats off the wall of the attic and place them in a large "tupperware" container for relocation.  My trusty sidekick, Marshall, would be standing behind me armed with a butterfly net to catch any animals that took flight.

I put on a hefty glove and began carefully removing the somewhat torpid bats off the wall, placing them in the container.  As I removed about the fourth bat, the inevitable happened.  A flock of bats fluttered up into the crawlspace like a covey of quail.  After a moment of indecision, I yelled for Marshall to start the netting process.  Upon receiving no response, I turned to find Marshall gone and the net lying limply on the floor of the attic.

Bats are extremely beneficial to human beings.  According to the book "Bats of the United States" by Michael J. Harvey et. al., a single bat can consume 4500 small flying insects in a single night.  Imagine what a colony of a thousand bats individuals could accomplish.  If bats were not present, we would have to spray far more insecticide into our skies to control mosquitoes and other pesky bugs.

Bats are the only true flying mammals. Similar to those of a human arm and hand, the extremely elongated finger bones are covered with membranous skin forming a wing.  Bats are spectacular aerialists, swooping and maneuvering to catch insects on the wing.  They use echolocation (sonar) to navigate and locate their prey.  They emit pulses of high frequency sound and listen to the echoes that bounce off various objects sensing what is in their paths.  Although bats are primarily nocturnal, they can often be seen at dusk, preparing for night flight. They spend days in attics of houses, barns, or hollow trees. Common predators of bats include snakes, owls and raccoons.

Because of past misconceptions, bats are still regarded as unwanted pests by some people.  Bats are beneficial because they play important roles in pest control, seed dispersal, and pollination.  Many people have even warmed-up to the idea of having bats in their attics, barns and yards .  Numerous plans for artificial bat dwellings (bat houses) are available on the internet and in outdoor magazines.

Marshall and I did manage to catch many of the bats in that attic. After a bit of research, I determined they were big brown bats Eptesicus fuscus, a harmless and beneficial species common in the the lowcountry.  In fact, this group turned out to be a maternity colony with lots of bat "pups."  I relocated the bats many miles away, in an old, dilapidated farmhouse where I had seen many bats in the past. I asked my neighbor to place hardware cloth over the gaps in the eaves of her house so no additional bats could get back inside and as far as I know that solved the problem.

-tony