The Short-Tailed Shrew, an evolutionary superstar

He [Raven] looked about and thought there was nothing on the land as lively as the fish in the water, so he made the shrew-mice, for he said, “They will skip about and enliven the ground and prevent it from looking dead and barren, even if they are not good for food.”                                                                                     – from Clara Bayliss’s 1909 collection A Treasury of Eskimo Tales.

Northern Short-Tailed Shrew (Blarina brevicauda) sniffing the air for prey

Creation myths aside, our early mammalian ancestors were little omnivorous insectivores very much like modern shrews.  Mammals evolved some 200 million or so years ago and lived alongside the dinosaurs, but did not grow to large size until millions of years after the dinosaurs went extinct some 65 million years ago.

Today we are a diverse group of flying, swimming, and running creatures ranging in size from the blue whale 120 feet long with a heart the size of a small car down to shrews no more than a few inches long, weighing less than an ounce.  We don’t know much about our early ancestors, small terrestrial creatures rarely leave fossil remains, but from what we can tell it seems that the shrew body design and hunting strategy is extremely successful and has remained a persistent mammalian body plan.

Shrew-like creatures live all over the world and are renowned for their ferocity, appetite, boldness, and their unusual (at least in mammals) venomous bite.  Here in Vermont the shrew you are most likely to encounter is the Northern Short-Tailed Shrew (Blarina brevicauda).  As near as I can make out, Blarina roughly translates to “nose-necked” and brevicauda actually does mean “short-tailed”, making this one of the few animals that has a matching common and scientific name.  Shrews are in the Soricidae family, which just means, “the shrew family.”

Short-Tailed Shrew running over freshly cut grass

Shrews move rapidly, driven by their rapid metabolism and resulting need to eat constantly.  They move with a peculiar blend of short, jerky twitches and weasel-like fluidity.  The shrew in the photos was hunting for insects and earthworms in freshly cut grass.  I followed it for perhaps 200 feet, and during that time it only stopped to sniff out prey, to eat it, and to hide from the dog that wanted to know what I was watching so avidly.

Like many predators, shrews are curious, engaging in high risk, high reward activities.  Their eyesight is poor, but their sense of smell is excellent.  How good their hearing is seems to be uncertain, some people thinking it is good, others poor.  I suspect that it is pretty good and that they are sensitive to vibrations via their whiskers and feet.

Searching for food

Unlike many animals the shrew had no fear of me what-so-ever, not even flinching when I stroked its back as it ate one of the 4 earthworms it caught while I was watching.  Every small animal nearby, on the other hand, was terrified of the shrew.  Insects froze into immobility, antennae twitching and heads slowly tracking as the shrew passed by.  Well should these creatures be wary of the shrew.  If a shrew goes more than a few hours without eating it will starve to death.

Short-Tailed shrews are tiny, massing between 2 and 5 US quarters (about .5 to 1 ounce), but they are perfectly capable of killing and eating prey several times their size.  There is a 3 minute National Geographic TV video of a shrew exploring a garden, then killing and eating a garter snake much larger than itself.  Most of the time shrews will content themselves with insects, worms, and seeds.

The dense fur of a shrew

Shrew fur is thick and dense, like the fur of an otter, but lacking the oily guard hairs.  The fur is so dense that it is waterproof, allowing some species of shrew to hunt underwater.  Shrews need this dense fur to keep warm through the winter.  Their small size means they lose heat quickly, necessitating both a rapid metabolism and good insulation.  In winter they remain beneath the snow as much as possible, eating cached food, keeping activity to a minimum, and burning brown adipose tissue (what we commonly call “brown fat”) to keep warm without resorting to shivering.

They have as many predators as they have prey, but their venom and unpleasant musk helps to keep some mammalian predators at bay.

Shrews are tremendously strong for their size.  I could see the back and neck muscles bulging as this shrew pulled earthworms from the soil.  It pulled a short section of the worm from the ground and ate it, pulled another short bit, ate that, and continued, as though it was eating Twizzlers at the movies.

Pulling an earthworm from the ground

We humans are proud of our accomplishments, but perhaps we should be more humble before the little shrew.  This tiny creature, so easily killed by a careless foot is upholding 200 million years of successful mammalian tradition, wearing a body design that gave rise to all other mammals from humans to whales, bats to elephants, beavers to monkeys.

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Blue-Eyed Grass, diminuitive irises

From California to New England, from Alaska to Texas there is a small, easily overlooked wildflower that is blooming now and will continue to do so for several more months, depending on where you are of course.  The flowers of this plant are small, only a little more than a centimeter across have six petals, a yellow center, and are often blue in color, hence one of the common generic names, Blue-Eyed Grass, although there are yellow and white variations.  To see them clearly you have to get close, crouching or laying on the ground.

Common Blue-Eyed Grass (Sisyrinchium montanum)

You can see from the photo that the leaves of this diminutive plant are broad and flat, much like the leaves of the grass it grows amongst.  In Vermont there are several variations of this plant, Sisyrinchium montanum being the most common, hence the name, Common Blue-Eyed Grass, which is, unfortunately, not tremendously imaginative.  When it is not flowering it’s easy to see why it might be mistaken for a grass, it has a similar leaf shape and is of a similar height to the grass it grows amongst.  The flowers clearly set it apart though.  Petals are little flags to attract insects, birds, and in some cases lizards or mammals to the flower for pollination for which they are rewarded with nectar.  Grasses have no such need, like willows, poplars, and pines they rely on wind to distribute their pollen and petals are a hindrance and a waste of energy for a plant that uses wind rather than animals for pollination.

Wind pollinated grass flowers with Blue-Eyed Grass flowers in the background

Sisyrinchium, the Blue Eyed-Grasses are tiny irises.  The Iridaceae family is widespread and often used as ornamental plants in gardens or in bouquets.  The larger irises have showy, ornate, soft flowers that fold and flow in complicated shapes, looking little like the small, robust Sisyrinchium flowers.  In the wild, the larger irises tend to grow in places that are either damp, shady, or both.  The Blue-Eyed Grasses live in harsher regions, open meadows, occasionally on rocky ledges, the edges of open areas, in short, places that can get hot and dry.  This may partially explain their small, robust stature.

Like other irises Sisyrinchium has inferior ovaries, this is not a commentary on the quality of the ovaries, it is a botanical term meaning that the ovaries are below the flower rather than the flower surrounding the ovaries.  These little plants produce globular three-part capsules about the size of a BB filled with numerous little seeds.

Blue-Eyed Grass with immature seed capsules

I grew up looking at these little flowers on the wildflower rich coastal prairie of Northern California, but just a few days ago I discovered something new (to me) about them.  They are active, they open their flowers for the day and close them for the night.  I tried my hand at a time-lapse of a flower opening.  It’s a bit rough, but you get the picture.

Blue-Eyed Grass flower opening animation

I love finding out things, being surprised by life, experiencing the unexpected, and encountering things I do not know.  I’m glad that these little irises reminded me that such a small, seemingly mundane thing can be interesting and exciting.

Chickadees, survivalists extraordinaire

It seems likely that weather is the only killer so devoid of both humor and dimension as to kill a chickadee.”

Aldo Leopold wrote this line back in 1949 in his incredibly influential book, A Sand County Almanac.  He was commenting on the extraordinary longevity of chickadee 65290, a bird that had survived for at least 5 years following its banding in 1937.  Little 65290 may have been extraordinary, but a brief walk in the winter New England woods will rapidly convince you that chickadees as a group are exceptionally resilient little creatures.

Chickadee in the spring sun

Chickadees are very vocal, calling to each other throughout the year. You can hear some of their calls at the Cornell Bird Lab website.  Chickadees often travel in loose flocks, flitting about, hanging upside down from branches, stealing insects from spiders, scrounging for seeds, and chasing each other about in the forest like a group of excited 5 year old children just released from a long, boring bus ride.  Their colors are subdued, yet distinctive: black, gray, white, often with a hint of yellow or tan on their underbellies.

Chickadee acrobatics

Black-Capped Chickadees (Poecile atricapillus) are cold weather specialists with a home range extending from Alaska to New England and dipping as far south as the mountains of Arizona and New Mexico and along the spine of the southern Appalachians (map).  I find this is extraordinary.

There is a principle of physics called the square-cube theory that relates the volume of an object to its surface area.  Basically, this can be simplified to the idea that a mouse has more surface area compared to its volume than does an elephant, and that for every time you double the size of an object its mass goes up by eight times (Length x Width x Height).  In terms of survival in cold climates this is really important because smaller things lose their heat far faster than large things because of that ratio of surface area to volume.

Chickadees are tiny.  Their bodies are barely larger than a golf ball, and much of that is feathers.  All told they probably weight as much as an emaciated mouse, yet they live in a part of the world that is well below freezing for great portions of the year.  During the winter nights chickadees huddle in cavities in trees in semi-torpor, burning fat at a prodigious rate.  At first light they are up and spend the day searching for food.

Feeding Chickadee silhouette


All living things have to balance the payoff of their behavior with the potential risk that behavior carries.  Some species are extremely risk-averse, in political terms these species might be the Ron Paul’s of the world, insisting on a gold based currency.  Chickadees are the opposite, they are inquisitive, curious, bold, and fearless.  As in many animals, their willingness to take risks is dependent on availability of resources.  You see this in humans, a far greater proportion of low income people spend their money on lottery tickets than high income people, despite the abysmally low chance of getting a winning ticket.  If you have few resources you will take more risks to get a large reward.  The costs of those risks are higher for those with fewer resources as well.  For chickadees this means of food and a place away from that humorless weather.

Keeping warm in winter takes more food than in summer, and food is more difficult to find.  Chickadees take risks to get that food, they investigate new objects almost as soon as they encounter them, they come closer to humans and stay longer than many other birds, and they try new things.

Traveling in groups is one way to offset the individual risks these brave little birds take.  More companions means more eyes to watch for danger (and food as well), and chickadees have a very well developed warning system that alerts their companions not only to danger, but to the degree of danger.

The risks they take, their small size, and the harsh weather they endure takes its toll and chickadees do not live long, hence Aldo’s comments on chickadee 65290.

Chickadee and hungry young

Chickadees may not live long, but their lives seem bright and full of vibrancy.  They are a reminder of the importance of curiosity, companionship, and communication.

Meteor Impacts and Ourselves

I am fascinated and enthralled by things that fall from space and the marks they leave behind.  It’s not just my love of space, it’s is something far more profound, it is in part what those things signify.

Go to a museum, one that has meteorites.  Often there will be at least one display of a metallic body that you can touch.  Lay your hands on it, press your palms against it, feel the soft curves, the slightly nubby surface, the coolness of the blackened metal.  You are touching the core of an extinct planet.  That should give you pause and send a small shiver up your spine.

On Earth there less than 200 known, confirmed, impact structures.  Just looking at the map it is clear that the distribution is skewed to areas where there are many people (North America & Europe), exposed bedrock (Canada & Scandinavia), or regions where weathering is slow (Australia & North Africa).

Confirmed impact structures on Earth from: www.meteorimpactonearth.com

Every other rocky body in the solar system is liberally coated in the scars left by impacts.  The Earth bears the history of its impacts in a different way.  Weathering, plate tectonics, and the oceans have served to hide the marks of the numerous past impacts.  Except…

The global ocean, that covers 70% of the surface of the planet to a depth of 7 miles in some places, this, the single largest surface feature of the planet, is impact derived.  It is believed that ALL the water on the planet arrived by cometary impacts soon after the planet formed.  The Moon is another large impact structure, a relict left over from  the collision of the proto-Earth and another roughly Mars sized body.

The frequency of large impacts has, thankfully, fallen over time, but they still happen.  Some of you, I hope all of you, may remember the comet Shoemaker-Levy 9, the comet that crashed into Jupiter in 1994 after being torn apart by Jupiter’s immense gravitational field.  The fireballs in Jupiter’s atmosphere were larger than the entire Earth, and there were multiple fireballs.

Shoemaker-Levy 9 impact on Jupiter

The energy released by each of the Shoemaker-Levy impacts was on a par with the Chicxulub impact in the northern Yucatan 65 million years ago that is implicated in the demist of all terrestrial animals larger than a piece of carry-on luggage.

On Earth impacts are still frequent, but most are small and do not survive passage through the atmosphere.  Think shooting stars, grains of sand and dust traveling at orbital speeds, around 20km/second.  Several months ago, on the last day of February, I was treated to a something more dramatic than one of these little grains of dust.  A little after 10pm on the 28th I was driving under a clear sky and the snow covered landscape lit-up with a bright blue flash.  I later found out that the flash of light had been seen from New Jersey to Quebec.  This was just one of the many fireballs that flash in the sky each year, probably something small only a few meters in diameter, an explosion not more than a few kilotons.

In a few places the scars left on the ground from large impacts are still visible.  One of my favorite ones is in NE Canada.  Canada is an excellent place for finding impact structures as much of the Canadian Shield is ancient, exposed bedrock.

Manicoaguan impact crater turned into a reservoir

The Manicoaguan impact is about 215 million years old and approximately 60 miles across.  It has been dammed and the island in the middle is now one of the largest fresh-water islands in the world.  Big impacts like this are rare, but they leave dramatic remains behind.

Small impacts are surprisingly common, the frequency rapidly trailing off the larger the impact.  This is good news, but the picture is very incomplete as we have only been able to watch carefully for a short period of time.

Impact frequency Table from geology.com

We are struggling to understand how the universe fits together and have tremendous difficulty comprehending the scales and energy involved.  We are too used to thinking on our small scales, our bodies, our houses, maybe our planet, for a few our solar system or galaxy.  Our solar system is huge, our galaxy immense, yet in the lager context of our body of knowledge and what we can see even the Milky Way galaxy is barely a microscopic speck.

Look at the ocean, lay back and watch the trails left by falling meteors, look at the background of stars, go to a museum and touch the heart of a planet, if you live near an impact crater go visit.

We often say, “We are all connected,” and this is true, and that web of connection is far greater, wider, and deeper than most of us realize.

The Fiercest New England Animal

Squirrels are polarizing creatures, people love to hate them.  The Red Squirrel (Tamiasciurus hudsonicus) of North America is no exception to this.  In New England this common little red and black squirrel is particularly reviled by many people.

Alert Red Squirrel

Chickarees (Chickaree is a local New England onomatopoeic name) are fiercely territorial, ill mannered, noisy, chew holes in people’s houses, and raid the nest of birds, eating eggs and baby birds.  As you walk through the woods these fiery little creatures will drop what they are doing and run to harangue you, precariously balancing on thin branches a few feet over-head, twitching, chirping, and generally expressing their dissatisfaction with your presence.

A legend attributed to the Abenaki people relates how when the world was young red squirrels were enormous, the size of large bears.  Life was hard for the people and the rest of the wildlife in the forest as these enormous beasts would raid long-houses, carrying people off to devour them, chase away game, and pillage the fields, eating all the corn and squash just as it ripened.  The people begged the creator to do something about the marauding squirrels.  In response to their prayers the red squirrels were made smaller, small enough to fit in one’s hand.  Despite their small size, their fierce nature remained intact.

Stealing from a bird feeder in the rain

Today they raid our bird feeders instead of our long-houses.

I think they are wonderful little creatures.  I admire their boldness, agility, and integral role in keeping the forest healthy.

Red Squirrels and their cousins, the Douglas Squirrel and the Mearn’s Squirrel, fall into the category of Pine Squirrels, and have an enormous range.

Squirrels are, in many ways, a keystone species.  They, along with jays, distribute seeds, carefully planting them in storage caches where uneaten seeds germinate far from the parent tree.  Red squirrels are a primary food source for northern goshawks, ermine, martin, fisher, red-tailed hawk, lynx, bobcat, and long-tailed weasel.  They eat the new buds of many tree species, effectively pruning the trees promoting branching which leads to long term increases in leaf density and seed production.

The discovery of maple syrup is attributed to observation of red squirrels chewing through the bark of sugar maples to drink the sweet sap.  Native people copied this, collecting the sap in wood and bark trenchers to dry, concentrating the syrup.  European colonists refined this process further, but it is not so different from what the red squirrels did and still do in the woods.

Like all rodents, their front teeth never stop growing, and they must gnaw on things to keep their teeth short.  It is common to find bones and antlers gnawed for the calcium they contain.  We complain when they chew through eaves of our houses, gnaw the handles of our tools, or demolish our bird feeders, but it is not really their fault.   We are the ones who left those things where the squirrels could reach them, knowing full well the proclivities of these sparky little creatures.

Red Squirrel warning me away

If you walk in the New England woods you cannot but help hearing or seeing these feisty fellows.  Often they will be perched just above you, twitching and glaring.

If you walk quietly and slowly they may not notice your presence, and you may find one sitting in the sun calmly grooming itself.

Sometimes you just have to scratch that itch

Meeting Bears

I like bears.  I like a lot of animals, but bears are special and I have been fortunate enough to have a number of close encounters with bears in a great number of places.  Some of these encounters have been humorous and some exciting.  Mistaking a beaver carrying a log through the underbrush for a grizzly in interior Alaska in an area where grizzly encounters have been, well… grisly, was an occasion for much relieved laughter.  Waking up in the mountains of northern California to a black bear pawing my shoulder through the tent wall sent my pulse racing and elevated me into the small group of people who have actually punched a bear.  I briefly worked in Ecuador following and catching Spectacled Bears (Tremarctos ornatus) in the Andean cloud forests.  When I was little my nick-name was Little Bear due to my love of climbing trees and the immense amount of honey that I ate, and still eat to this day.

As I said, I like bears, they feel like family.

Spring has come to Vermont and all sorts of plants and animals are waking up.  The fields are green and full of flowers, and this greenery draws animals.  On Sunday I ran across a female black bear with a single cub in a field next to my house.  I was returning from buying groceries and she was eating hers, a mid-day salad of grass and dandelions.

Female black bear and cub

I pulled into my driveway, ran inside to grab my camera, and jogged back down the road to watch her.  Shortly after I arrived a car stopped on the road next to the field and the skylined car scared her.  She gathered her cub and retreated into the forest.  Roughly toward my house.

One of the secrets to following animals is to give them time.  If they are startled and you hurry after them they will run further.  It’s a little like when you meet someone you’re interested in, you can’t push too hard, people and animals need their space.

After lunch I strolled into the forest.  There are many ways of walking and many ways of looking.  My preferred way is to let my feet and subconscious carry me along at a slow, quiet pace.  Inevitably I wind up walking on subliminally visible game trails.  Frequent pauses to look, listen, and sniff the air set a broken rhythm that seems to set animals at their ease.

Every time I cross an environmental dividing line, an ecotone, I pause.  Standing in the shade of the trees before entering a field, for example, lets you and everything else adjust.

The little trail my feet had been following had a few piles of old bear scat and some odd little fresh tears in the duff layer… maybe from a playful cub?  The trail led to the edge of a small forested wetland and I paused, looking, listening, and smelling.

Momma bear in the woods

There she was.

Black Bears (Ursus americanus) are an amazingly successful species, despite all we have done to wipe them out over the years.  Bears in general are extremely successful, but black bears are apex generalists.  They are large and powerful enough that few animals will pester them, can eat everything from pine cones to grubs to freshly caught fish and small mammals.  If they find carrion they will happily eat that with no ill effects, and they are intelligent enough not just to raid our garbage cans, but to know what models of cars are easiest to break into and how to follow ropes to where they are tied when we hang food.  They are strong enough to tear logs apart and shatter car windows with a push, but delicate and dextrous enough to open clams they have dug up and tins of food they have stolen from humans.

They are faster than we are, can smell absurdly well, something like 7 times better than a bloodhound, but have poor vision.

This female knew I was nearby.  Her sharp ears picked up my sounds, but I was down-wind and she couldn’t see me clearly.  She looked for me, even climbing a short way up a hemlock tree to get a better view.

A protective mother looking for me

Eventually the wind shifted and she caught my scent.  She swiftly trundled off.

To me bears are the wild people of the woods.  Gentle, wise, powerful, and deliberate.

Often when we encounter bears it is in a context where we have invaded their space and they are turning their talents to adapt to the changes we have imposed on them.  In those contexts neither the bears, nor ourselves know the rules of interaction.  We are both caught wrong-footed and the reactions of both parties are not what they should be.

If you are fortunate enough to encounter bears in their own habitats, and if you are comfortable there, the interaction is something else entirely.  It is an interaction of mutual respect and wary curiosity, two potentially powerful creatures meeting, aware of each other’s strength, each wise enough to not push the issue.

When you meet a bear, it is a privilege.

Discoveries in the Moss

Yesterday I saw an unfamiliar flower blooming outside my window atop the moss covered rocky ledge and I went outside to see what it was.  It looked a little like soaproot (Chlorogalum  spp.) flowers, but those do not grow in Vermont.  As it turned out the “flowers” were the unfurled, pubescent new leaves of a young striped maple (Acer pensylvanicum), a very common plant in New England, and not as interesting as the other thing I found outside my window.

Crane Fly pupating

You see crane flies (Tipulidae spp.) often, they look like large mosquitoes and often go by the common name “mosquito hawk”.  Unfortunately, they only look like mosquitoes and do not hunt them.  Fortunately, they only look like mosquitoes and do not act like them.

I didn’t know much about crane flies, so I did a little reading about them and now know minimally more than I did.  Not enough to identify this species unfortunately.  When I first found the pupating insect it was holding its wings wide, but when I returned with a camera it had folded them back along its body.

Crane fly wings

The larvae of some species live under water, much like caddis fly larvae, other species have terrestrial larvae.  In either case the larvae eat dead vegetation.  The larvae of terrestrial species have tough skin, leading to the common name “leather jack”, which I think is pretty cool.  Skunks and moles eat the grubs, as, I expect, do birds when they can get them.  The adults of most species do not eat, and in some species only the males have wings.

I turned my back for a minute to take a photo of a leaf-hopper sitting nearby, and when I turned back, the crane fly had gone.

Leaf-hopper or Sharpshooter, not sure which

Hunting around with the half-formed though that if I had seen one, there might be others (always worth checking, sometimes it pays off).  I did not find any others hatching, but there was evidence that others had hatched recently.

Case left behind by a hatched crane fly

Insects are one of the most mysterious and magical things.  They transform themselves in ways that seem impossible, ones that pupate completely breaking down their bodies and reconfiguring them in radically different configurations.  Tests on butterfly caterpillars indicate that, despite pretty much liquifying themselves, they retain memories and lessons learned through the process.  Insects are so successful that nearly every ecosystem and terrestrial living thing is now dependent on them, if not directly, then removed from direct dependence by only a step or two.

We don’t know how many species exist, and often fail to grasp their importance.  We try to kill the insects we dislike with poisons and within a few generations they develop immunities.  They are mind bogglingly tough and adaptable, despite their individual fragility.

They are ubiquitous, fundamental, and wondrous.