A whisker of shrewlets

By MCHT Nature Bum Steward Kirk Gentalen

Alright, we’re going to cut right to the chase here with this post. I had an encounter with a “whisker of shrews” (I just learned that collective noun). It was on a Midcoast Maine beach, of which I am not at liberty to say (let’s just say I was working), when I noticed a fuzzy little ball of brown racing along the wrack line. It was no further than 10 feet away from me. “Rodent” was my first impression, but when the fuzz ball started darting around sniffing everything like a frenetic pinball, I knew it was a shrew! Nothing moves quite like a shrew.

I knew it was a shrew. Nothing moves quite like a shrew.

I happened to have had my camera out— “at the ready” as people like to say—and started snapping shots in classic nature-observer fashion, from a distance and at all kinds of angles in case it disappeared (which it never did). I took about a hundred photos (thank you, digital camera!) from about eight feet away, and then noticed there was another brown fuzz ball on the far side of the hiding log. But wait! There were two fuzz balls running amuck along the far side of the log! A family it seemed to be and in the end, it turns out they were likely siblings that had been weaned, maybe that day or even just minutes before. Setting yourself up for success (being in the right place and looking) is super important in nature observing, but timing really is everything. I had walked by that spot four times already, but the right time for shrew watching was finally here, and there they were.

Shrews on the move

I took a stealthy step closer and then another, and then one more… I noticed no change in the shrews’ behaviors. Eventually, I was standing next to them, almost towering over them. They did not seem bothered by my presence.

I see shrews maybe a couple of times a year, often it’s no more than a quick flash of movement. Once, my friend John and I watched a shrew scurry across an ice sheet that had formed over a tidal land bridge connecting one island to another. We watched it go 15 feet in an impressive outpouring of energy and effort. It was exhausting just watching it.

At first glance, shrews come across a bit like highly caffeinated mice.

At first glance, shrews come across a bit like highly caffeinated mice. In the woods their frenetic rustling around in leaf litter can be downright loud. They also lack a certain amount of short-term memory (or any long-term memory for that matter) and thus their survival instincts aren’t always apparent. They are too busy looking for food to be threatened by the approaching, towering creature (me) that weighs about 14,080 times more than they do. They don’t seem to scurry away at all, which makes me think they are seldom seen, not because they are particularly good at hiding, but more likely because their more often hunting in well protected habitats… I think that is called survival.

Getting’ Shew’d

A shrew

I ended up enjoying an extended afternoon with these beach-loving youngsters, which was likely due to their young age (welcome to earth!)—I imagine that I was the first human they ever saw (although I’m not actually sure if they saw me). The rocky beach habitat made a difference as well. There was one log to hide under, but the shrews weren’t interested in hiding (or so it seemed), they were interested in eating. And the prey they were mackin’ on were amphipods living in between rocks and in the washed-up seaweed, not worms under leaves or critters in tall grass.

A few Shrew basics

Shrews (family Soricidae) are small mammals classified in the order Eulipotyphla. Eulipotyphla can be translated as “truly fat and blind.” It’s an order whose members also include moles and hedgehogs. Historically, shrews have fallen into the “insectivore” group of mammals, but that division seems to have been eliminated (probably due to increased knowledge and understanding through DNA research). But they still live off insects and a variety of other living creatures. So, beyond superficially resembling rodents they kinda live a different lifestyle. Carnivorous.

Shrews are the smallest mammals in North America, but don’t let their size fool ya. While they mostly eat invertebrates, shrews are also known to eat small mice and salamanders, as well as fungi and seeds. They hunt mostly by a combination of smell and touch—those whiskers are sensitive! They have eyes, but just how much they use them is up for discussion. Shrews use underground tunnels and paths below leaf litter or through grasses, and are mostly nocturnal, light is not necessarily a big part of their life. They didn’t seem to see me at all on the beach, or maybe they did and my beard made them feel at ease. Maybe, maybe not.

In captivity, many species will eat two or more times their weight in food each day

Here’s a quote from Fiona Reid from the Peterson Field Guide ‘‘Mammals of North America’’

“They are well known for their nervous and high-strung behavior as for their legendary consumption of food. In captivity, many species will eat two or more times their weight in food each day and may die of starvation or stress if food-deprived for a few hours. In the wild many shrews are exposed to periods of food shortage. They survive these periods by resting or becoming torpid.”

Thanks Fiona! And may I say, what a lifestyle! I remember back in the day (college) learning about using live traps for scientific mammal population surveys and being told to always put food and natural materials in the traps in case you caught a shrew. Without the food and materials to keep warm the shrews could die overnight! In the name of science!

Life in the fast lane

Back in the day (college) I was introduced to the idea that mammals that live to the full extent of time that their bodies can support would all have a similar number of heartbeats over their entire life. The number that we see again and again is one billion heart beats per mammal. This concept means that any mammal without predestined health issues (genetic bummer) or crossing a path with unfortunate timing (such is life) gets roughly one billion heartbeats before their heart stops. I did not make that number up, but I also don’t know if it’s totally accurate, but le’s go with it!

This is a good way to compare heart rates between species. For example, the heart of a healthy human surviving to 90 (ish) would have the same (or close to) number of beats as the heart of a humpback whale that lives to 150 (ish).  This goes to show, the heart rate of a Humpback Whale is much slower than that of a human.

Well, shrews in the wild have a life expectancy of about 14-16 months, depending on species. For a fully aged, 16-month-old shrew whose heart reaches the one billion mark this would mean 62 million 500 thousands heart beats a month.

Shrew natural history fun facts…

“Shrews are unusual among mammals in a number of respects. Unlike most mammals, some species of shrews 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 by intravenous injection. One chemical extracted from shrew venom may be potentially useful in the treatment of high blood pressure, while 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 soricidin, a peptide which has been studied for use in treating ovarian cancer. Also, along with the bats and toothed whales, some species of shrews use echolocation. Unlike most other mammals, shrews lack zygomatic bones (also called the jugals), so have incomplete zygomatic arches.”

Unlike most mammals, some species of shrews are venomous.

“Shrews are unusual among mammals in a number of respects. Unlike most mammals, some species of shrews 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 by intravenous injection. One chemical extracted from shrew venom may be potentially useful in the treatment of high blood pressure, while 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 soricidin, a peptide which has been studied for use in treating ovarian cancer. Also, along with the bats and toothed whales, some species of shrews use echolocation. Unlike most other mammals, shrews lack zygomatic bones (also called the jugals), so have incomplete zygomatic arches.”

Before you go all zygomatic on me, what this means is that shrews are cool. There’s a lot going on with those little buggers. And it turns out that while we don’t see them all the time, there are lots of them out there!

“The shrew family has 385 known species, making it the fourth-most species-diverse mammal family. The only mammal families with more species are the muroid rodent families (Muridae and Cricetidae) and the bat family Vespertilionidae. The shrew family also probably has the largest population of any mammal family: there are an estimated 100 billion shrews in the world, with an average of a few shrews per hectare of forest.”

Is that the coolest or what?

Whatsmore… From Fiona Reid once again…

Playful young perhaps?

“Shrews are typically solitary in habitats and can not be maintained together in captivity.”

This confirms the hunch I had that the shrews I was watching were young. Not only were they oblivious and way (WAY) out in the open and exposed to dangers, but they were also getting along very well. Rolling and tumbling with each other with no parental supervision gave me the impression that these shrews were still very young. Which begs the question, “at what age does a shrew grow up?” Is it three, months? Four?”

“Shrews are often very difficult to identify to species level. Shrews are often dead when encountered, allowing close inspection. It is often necessary to examine teeth with a hand lens to confirm identification.”

So here is the funniest part of the shrew encounter. After hanging with these youngsters, and taking about a gagillion photos (and some videos) I’m still not totally sure what species they were. And no, it’s not all about identifying things, but when you have the photos in front of you, and such a close encounter fresh in your mind and you still aren’t sure, well, that’s just another piece of the shrew puzzle that makes them so cool. Birds are easy, shrews are shrew’d.

Birds are easy, shrews are shrew’d.

So I thought to myself, “what shrews are in Maine?” There aren’t that many choices to begin with really. They certainly weren’t large shrews—which means they couldn’t have been northern short-tailed shrews (Blarina brevicauda). They had relatively long tails, which means they could not have been the pygmy shrews (Sorex hoyi). This leaves us with the smoky shrew (Sorex fumeus) and masked/cinereus shrews (Sorex cinereus).

The shrews’ pale hind feet resembles that of a smoky shrew, but the size of the shrews made me think it was a masked. One resource mentioned that smoky shrews are full grown when weaned… were these medium sized shrews then? How big is a medium sized shrew anyway? They seemed freakin’ tiny.

The coloration of what I saw on the beach seemed paler than what I saw smokey shrews described as or what they looked like in photographs, but could that be a freshly weaned kind of thing? The tail was bi-colored, but not as dark as what I’d expect for Masked shrew. But still, were the feet light enough and the tail pale enough to make them Smokies? Just writing all this makes me lean more towards Smoky than before. Smoky was my first instinct for identification! So maybe they were Smokies all along. I wish I got a better view of their teeth!

“It just doesn’t matter!” – a quote from Meatball

I had a ball during my beach time shrew session, watching a whisker of shrewlets just get to be shrewlets. Another set of youngsters in what has become “a season (or two) of youngsters” this year. Since seeing the shrewlets there have been other young wildlife to spot. Juvenile raccoons, deer and river otters have all emerged and are out and about exploring. Many songbirds are feeding their fledglings, providing a wonderfully demanding chatter in the woods, like the sound of young humans (humanlets?) at a playground who are demanding food, of course.

“Such are some of the challenges facing the many shrews that live all about us, largely unseen and unknown. Despite their small sizes and secretive natures, if you want to see a shrew the first thing you have to do is slow down. It is not difficult to hear shrews rustling around in the duff and debris of the forest floor, or even calling out in high squeaks as they forage, but you will need to be still to do so. If you are lucky, you may see one dart from under a folded leaf to a rotten log nearby, but be watchful – they scurry so quickly they are difficult for an eye to follow”- Elbroch and Rinehart

The shrew session takes the cake for me. Some of the best ten minutes I will spend all year. Timing was the key here, and I figure I will probably never have another session like this again, which is fine. Super fine in fact. I am not closed off to another shrew session, but I also don’t take them for granted. Hope luck is with you and you get to have a shrew session soon. Keep the coast shrew’d!

We’ll see you out there!

See more Nature Bummin’ stories from Kirk.