Street Creatures – January 19, 2018

More January, more mammals. And another fuzzy who isn’t all that wuzzy… although this grumpy fellow with his vivid, unnaturally-hued tresses does seem to have found his niche in the fashionably eclectic London neighborhood of Shoreditch (photo by duncan c, cc by-nc 2.0)

When a Mess is a Nest

Gray squirrel on a tree branch.

[Reprint from November 2010]

Winter winds have blown nearly all the remaining leaves to the ground. They lie tossed and trampled on the ground like post-holiday parade confetti. The hyperbole of autumn reds and oranges and yellows is long gone, replaced by browns, taupes, and grays.

But bare boughs and blue skies offer the perfect opportunity to pull back that leafy curtain for a peek “behind the scenes.” All you need to do is step outside… and make the leap from two dimensions into 3D.

Sure, we all know it’s a three-dimensional world, but with the exception of a flight of stairs now and then human days are usually spent in a forward-backward-left-right routine. Skeptical? Spend even a few minutes watching a gray or fox squirrel ricochet between branches and you’re guaranteed to feel like your days are spent in Flatland.

Unlike many mammals, squirrels make it easy for wildlife watchers. They’re not shy, they’re active during the day, and much of their activity occurs within the visual field between our feet and our face. Of course, while we keep our feet planted firmly on the ground squirrels do not, and when they bolt up the bole into dense foliage they seem to disappear like a Santa up a chimney. What good does it do to look up?

Dreys in a silver maple

Two dreys in a silver maple (Photo: KJ Lindsey, CCL 2.0)

In parts of the country that have both squirrels and seasons when trees go au naturel, craning one’s neck can be more rewarding during the winter months. That’s why I’m trying to cultivate a new habit during walks with my terrier-boy, Dash. Whenever I catch myself contemplating my shoes, which is often, I lift my eyes and scan the trees, starting at about the same level as the roof of a two-story house. Try it yourself. See those seemingly accidental wads of leaves and twigs, about the size of a football, caught in the gutters formed by branches? Those are squirrel nests, also known as dreys.

Squirrels aren’t as famous for their engineering skills as are beavers but maybe they should be.  It can’t be easy to build 20 feet or more above the ground on a foundation that sways with every breeze. Construction begins with a platform of woven twigs, followed by a spherical framework secured to the base. Leaves, paper, and moss are used to fill in the gaps and create a snug, weatherproof abode with two doorways—a main entrance and a hidden escape hatch. The exterior may look a little rustic but the interior décor is luxurious. Lined with fur, feathers, and other cozy furnishings, it’s the perfect cocoon for a cold winter’s night.

Closeup of a drey

Close up of a drey (© N. Hawekotte, used with permission)

Squirrels don’t hibernate but they do lie low during inclement weather. When the mercury drops or the snow starts to fly, a group of females may crowd into a single drey, kind of like a slumber party without the pajamas, pizza, and prank phone calls.

As spring approaches, the dreys serve a dual purpose as nurseries for the new crop of infants. I realize not everyone is a tree squirrel fan, but if you’re an aficionado and want the scoop on where to enjoy watching for youngsters when they venture out to explore the world and learn how to navigate in every direction, now’s the time to make note of which trees are littered with messy nests.

Just think 3D… without the funny glasses.

Have a question about wildlife and other next-door nature? Send me an email and the answer may turn up as a future blog post. And don’t forget to friend NDN on Facebook!

© 2010 Next-Door Nature — no reprints without written permission from the author.

Street Creatures – January 12, 2018

Continuing January’s mammalian theme… Consider the hippopotamus. While all mammals do have hair, they aren’t all furry. And speaking of deceptive exteriors, you probably wouldn’t guess based on looks alone that these sleek and nobel hipster beasts hanging out in San Francisco, California, are closely related to the dolphins (as well as whales and other cetaceans). Just goes to show, it’s better to judge a book by its DNA than by its cover (photo by torbakhopper, cc by-nd 2.0).

Hide and seek

meadow vole by manual crank

Meadow voles are sometimes referred to as mice and moles, but there is a difference (photo: Leo Papandreou, Creative Commons license)

[I’m attending a faculty retreat in a remote location this week so I decided to run this reprint from 2011. I’ll be back with new Next-Door Nature soon!]

Winter weekend mornings are perfect for catching a little extra shut-eye, but my fur-covered drill sergeant thinks it’s important to rise and shine on schedule, seven days a week. I can’t seem to dissuade him from this mindset.

There’s a snooze button on clock radios and even on my iPhone, but wire-haired fox terriers don’t come with that feature, as either standard or optional equipment. Snug in my blanket burrow, my sympathy for small, ground-dwelling creatures is renewed every time Dash excavates me from beneath the covers and insists, “GET UP! It’s time to OPEN YOUR EYES!!”

Once we’re wrapped in an appropriate number of layers and out the door he begins to search in earnest for that one perfect piece of real estate on which to make his mark. This takes some time—Dash has strong feelings about the importance of a job well-done. As we mosey along I often find myself absent-mindedly scanning the terrain as well (although I use my eyes instead of my nose, and with a different objective).

We had slightly warmer temperatures in southwestern Virginia this past weekend so there was more wildlife activity than when the mercury huddled near zero, and I noticed etchings in the dun-colored grass near our usual pathway.

meadow vole surface runway system 1

At first I thought the scribbles were the result of melting ice, but somehow that didn’t feel right. I took a closer look…

close up of meadow vole surface runway system

…and began to develop a hypothesis:  meadow voles. But if a vole was the engineer behind this winding road, where was the signature grassy-igloo nest?

meadow vole nestAha—I knew it! And not just one… there was a second nest.  I could read what had happened as if a book lay open before me. A blanket of white stuff builds up in the shadows and becomes a snowy fortress for an intrepid rodent willing to do a little mining. Food and building materials close at hand, there’s no need to venture out into the outside world of hungry predators.

Meadow voles (Microtus pennsylvanicus) claim many an alias: meadow mice, field mice, round moles, meadow moles. They are neither moles nor mice, but they are more closely related to the latter than the former. Moles are insectivores. Mice and voles are rodents. Unsurprisingly, then, there are physical similarities. Voles have shorter legs and tails than mice, but it’s dentition—their teeth—that caused mammalogists to set them apart from others gnawers. The upper cheek tooth row is relatively long compared to other rodents, and the third premolar has some distinguishing characteristics. Yeah, I realize that’s an observation that borders on nit-picking but taxonomists are a crowd that believes the key to life is in the details.

As soon as Dash finished his business, I dropped him off back home so I could take a closer look—you can’t sneak up on a rodent with an inquisitive terrier in tow. Smartphone in hand, I examined the carefully arranged, perfectly spherical, palm-sized mound of dried grass and wondered… had the nest become a nursery? Had the vole family tree added another branch? I listened carefully, but if a creature was stirring it wasn’t loud enough to register against my eardrums. The weather forecast calls for a general warming trend but I wondered… would the nest prove warm enough without its outer ice-cave shell?

meadow vole runway and nest Who was I kidding? I’m a woman of the natural world and I could see the writing on the sod. What had once been a well-camouflaged hideaway now looked like a treasure map for predators. If the other companion canines in our neighborhood overlooked these nests while on their quest for bladder relief, it’s unlikely the raccoons, opossums, and even tree squirrels in the woods just beyond the pavement would be so clueless.

I’m a tender-hearted soul, I’ll admit. I’m also a biologist and, therefore, an equal-opportunity empathizer. I hate to think of vulnerable pink babies being gobbled down, but I wouldn’t like to see a starving raccoon either. Some creatures die so other may live. It’s the way of this world.

But while they are alive, in the course of going about the business of living, voles make a unique if fleeting mark on the world that can be discovered and appreciated by anyone who will open her eyes.

Thank you, Drill Sergeant Dash, sir!

Have a question about wildlife and other next-door nature? Send an email and the answer may turn up as a future blog post. And don’t forget to “Like” NDN on Facebook!

© 2011 Next-Door Nature— no reprints without written permission from the author.

Street Creatures – January 5, 2018

In most of the northern hemisphere, January is a time when amphibians and reptiles take cover from the cold, and many migratory birds are spending their time at their winter homes in warmer latitudes. But the majority of our native mammals stay put and weather the cold along with their human neighbors. So, in honor of our fellow mammalians, this month’s Street Creature feature will focus on the fuzzy… starting with this decidedly uncuddly tiger in the London borough of Camden (photo by duncan c, cc by-nc 2.0).

Urban development

Raccoons by John Biehler, Creative Commons license

Just hangin’ on the corner with the homies… smart, bored, and looking for trouble (Photo: John Biehler, Creative Commons license)

[Another reprint, this one from February 2012. I’ve been traveling over the holidays and due to some family-related changes to the itinerary I haven’t had much time to write. New stuff is coming, though. I promise. And is there a better way to start a new year than with raccoons? I think not!]

World War II had barely ended when researchers began to notice a major migration under way in North America, from undeveloped and agricultural areas to cities and suburbs.  Now, in the early 21st Century, the urban population is over 20 times that of the early-1940s—in some places, more than 50% higher than the surrounding rural landscape. With growth has come all the problems that naturally occur as a community becomes overcrowded: housing shortages and squatting; dumpster diving; increases in theft and property damage; sanitation-related public health concerns. sometimes, we all need a little help getting through the day... by jmtimages, creative commons licenseAll of this has a tendency to make established residents less tolerant of immigrants, even when the new neighbors are clever, ambitious, hard-working, good parents, and undeniably cute as all get-out.

Raccoons (Procyon lotor) may be new to the urban scene, but… oh, you probably thought I was talking about people, right?

That’s understandable, I suppose. Just about everything I’ve said to this point could apply to humans as well. There’s no denying that Homo sapiens is now an urban species. The tipping point (>50% of humans living in areas of high population density) came around 2007. Each year, more of us are lured by the promise of better-paying jobs, more housing options, access to social services and chain restaurants, bigger shopping malls, a larger dating pool, and high-speed Internet connections. In other cases, concrete tentacles sprawl past the city limit signs to grab up and devour surrounding countryside, forcing rural residents to choose between relocating to land that hasn’t yet caught developers’ eyes and becoming accidental townies.

urban raccoons by liz west ccThe “built environment” is intended to meet the wants and needs of our own kind, but raccoons may be better suited for what we’ve constructed than the target real estate market.

Raccoon Nation, a documentary that aired in the U.S. on the PBS “Nature” series, and in Canada on the CBC News Network series “The Nature of Things with David Suzuki,” makes a strong case in support of that thesis.* As filmmakers follow the furry urbanites in their native North America (including Chicago and Toronto—known as the “raccoon capital of the world”), as well as in Germany and Japan (where they were intentionally introduced), it’s hard not to notice the similarities between those who construct cities and those who exploit them and their work.

How alike are we? Let’s build this case from the ground up.

raccoon paw and human handFeet—humans and raccoons are both plantigrade. In other words, we walk with the entire foot planted firmly on the dirt… make that asphalt. There are other examples (elephants, kangaroos, and pandas come to mind), but the majority of mammals walk on their tippy toes (more on this in a future blog post).

Hands—okay, technically raccoons don’t have hands, they have two more feet. Or you could say they do have hands but they just happen to use theirs for walking. That’s all semantics, though. Look closely and you’ll see one reason it’s so hard to invent a raccoon-proof container—a paw that looks a lot like a palm and a digit that’s as close to the functionality of an opposable thumb as it gets for non-primates.

dumpster raccoons by zeetz jones ccStomachs—the best way to avoid starvation long enough to pass your genes along to the next generation is to cultivate the ability to eat anything and everything you can cram in your mouth that contains a calorie. The human diet is astonishingly diverse, and urban raccoons gobble up everything we leave on our plates and toss in the trash… plus a lot of stuff we would rather not eat. Some researchers suggest that omnivory played a crucial role in human development—by providing a more consistent and more nutritious diet, and because finding potential new foods, determining whether they are edible, and figuring out how to eat them pushed our brains to create new neural pathways. Which brings us to…

Brains—raccoons and people also share a high level of behavioral plasticity, a term that implies the ability to change. Flexibility, adaptability, and life-long learning (well… we both have that capacity; whether we use it or not is another issue). With no email to check, no AYSO games to attend, no need to commute, and only one significant predator (those commuting automobiles), raccoons have plenty of time for learning. Each day is devoted to DIY personal growth, lifestyle enhancement, and honing useful skills, such as…

  • how to turn a garbage can or dumpster into a convenience store;
  • how to tight-rope walk a fence (great for avoiding the neighbor’s dog);
  • how to shimmy down a tree branch onto a rooftop;
  • how to turn a loose shingle on that roof into an attic entrance;
  • how to turn that attic into a cozy, rent-free nursery.

Whether you find these critters endearing or exasperating, it’s never fun to clean up refuse that’s strewn across your yard, and there’s no denying they can and do cause damage to property. Ironically, our attempts to outwit them are molding these savvy metropolitan mammals to better fit the world we built for ourselves. And here’s the other reason I will never invest my hard-earned money in some inventor’s guaranteed raccoon-proof fill-in-the-blank: because no human being will ever have as much time to devote to keeping a raccoon out of something as raccoons, often working in teams, are willing and able to devote to cracking the code. By trying to thwart them, we’re simply selecting for the traits that make a more worthy opponent and a better urban animal. An über-coon, if you like.

bipedal raccoons by David~O ccBefore you know it, they’ll be standing upright in line right beside us at Starbucks, waiting for a Venti Caramel Macchiato to help them wake up for the night shift.

Urban raccoons share another, disturbing commonality with their human neighbors—the toll exacted by easy access to a plentiful, high fat, high sugar, high calorie diet. Diabetes, hypertension, and cardiovascular disease may do more to limit their numbers, in the long run, than all the Hav-A-Heart trap-toting home and business owners, urban wildlife biologists, and nuisance wildlife control operators combined. Cleverness and dexterity are no match for the fearful symmetry of a predatory heart attack or kidney failure.

No wonder they call it the urban jungle.

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© 2012 Next-Door Nature—no reprints without written permission from the author (I’d love for you to share my work; all you have to do is ask). Thanks to these photographers for making their work available through a Creative Commons license: John Biehler (3 sepia raccoons); jmtimages (mother & child); Liz West (supper club); Stuti Sakhalkar (human handprint); Jon Stogner (raccoon pawprint); Zeetz Jones (dumpster ); David~O (bipedal).

Nutcracker suite

cardinal-grosbeak-crossbill

No, not Tchaikovsky. These are avian nutcrackers (left to right): northern cardinal, rose-breasted grosbeak, and red crossbill. (Photos: ehpien, Conrad Kulper, and Eugene Beckes, Creative Commons licenses)

[A seasonally appropriate reprint from December 2011. New posts are coming for the new year, I promise.]

Ever wonder why hens’ teeth (and any other kind of avian teeth for that matter) are rare? It’s because teeth are heavy. That’s a problem if you live life on the wing but can’t use a knife and fork to cut your meals up into easy-to-swallow morsels.  A bird’s beak (aka bill) is an adaptation to flight that serves most of the same functions choppers handle in Earth-bound creatures… but without the high metabolic cost of carrying around a set of pearly whites.

Bird Beaks by Shyamal and Jeff Dahl, CC

Figure A. Beak shape and size offers a clue as to what the owner likes to eat.

The beak is a sheath of tough skin on the upper and lower mandibles. Wild birds exploit a wide array of feeding resources and niches, and they are aided in this task by a startling diversity of beak morphology (see Figure A). For example, nectarivores (nectar-eaters), including hummingbirds, usually have long, straw-like beaks that reach deep into flowers. Insectivores (insect-eaters) tend to have narrow, slightly curved beaks that can reach into the small crevices where their prey try to stay out of sight. Piscivores (fish-eaters) have a sharp hook, serrated edges, or both, that help them hold on to their slippery supper. Some of the most distinctive beaks, though, belong to nutcrackers.

The northern cardinal (Cardinalis cardinalis) is a familiar and popular resident of cities and suburbs, possibly because it’s so easy to spot and identify. It’s so popular, in fact, that seven U.S. state legislatures have chosen this species to be their avian poster child.  At  8½—9” (21—23 cm) from jaunty crest to tail tip, it’s a medium-sized songbird with ahim and her cardinals by Steve Wall cc stereotypic nut- and seed-busting beak—short, stout, and cone-shaped. I like cardinals as much as the next person—I’m from St. Louis, after all, where you can walk down any street in the whole town and know you’ll see someone wearing a shirt adorned with a bright crimson bird perched on a baseball bat. But my affection is somewhat tempered by the fact that their beaks work equally well at crushing seeds and human skin, as I can personally attest. Who would guess you could have empathy for a sunflower seed?

The rose-breasted grosbeak (RBG, Pheucticus ludovicianus) is slightly smaller than a cardinal (7—7½” or 18—21 cm) with a pale, conical but more zaftig bill… a chestnut to the redbird’s hazelnut. Of course, it’s natural for kin to resemble one another, and the RBG is, in fact, one of 17 species known as the “cardinal-grosbeaks.”* Grosbeak—from the French grosbec (gros thick + bec beak) is a bit of a misnomer for this striking black and white bird with a cherry cravat (the females prefer a more sedate, sparrow-like wardrobe). Compared to the schnozzes sported by some members of the Cardinalidae clan, the RBG has a proud but modest snoot.

Although not as common as its stop-light colored cousin, human development—and the fire suppression policies that accompany it—have caused forests to sprout where once only grasses grew, allowing the RBG to expand its breeding and migration range westward (although the Rocky Mountains have proven to be a tough habitat nut to crack).  They’ve become a more frequent visitor to backyard bird bistros, where they like to snack on safflower, cracked corn, and black-striped sunflower seed. Insects and fruit are part of their diet as well, but seeds account for the majority of their calorie intake, especially during winter months.

As the name suggests, red crossbills (Loxia curvirostra) are true specialists. At first glance you might think this is a bird in dire need of an orthodontist, but that oddly shaped bill allows them to force open conifer cones and extract the tasty nutmeat inside. The muscles that allow birds to bite down are stronger than the ones used to open their beaks. But unlike cardinals and grosbeaks, who can clamp down with great force on tough-hulled sunflower seeds (and tender, well-meaning human hands), the crossbill can wedge the slightly opened tips of its bill between the scales of a tightly closed pinecone and then bite down, pushing the scale up to expose the kernel.

The red crossbill is extremely dependent on conifer seeds—wildlife biologists refer to animals whose very existence depends on a narrowly-defined habitat or food sources as obligate species. Most granivores (seed-eaters) start their lives eating protein-rich insects, making a dietary change once they reach adulthood, but crossbills feed on seeds from nest-cradle to grave. Of course, there are risks associated with being a specialist… we’ve all been warned against “putting all your eggs in one basket.” But as long as long red crossbill by eugene beckes ccas you follow the advice of Mark Twain and “watch that basket!” there are benefits as well. For example, red crossbills can raise young any time of the year—even during winter—as long as the cone crop is abundant. I guess some nutty looking adaptations are really quite useful.

The Clark’s nutcracker (Nucifraga columbiana) has also used the reliable conifer nut to expand its breeding season. But this member of the Corvidae family (jays and crows) takes the idea even further. It is a hoarder, storing surplus pine, spruce, and hazelnuts. They actually have a special pouch under their tongues which they use to clark's nutcracker by Jamie Chavez cccarry seeds over long distances. A single Clark’s can hide as many as 300,000 pine nuts over the course of a year, and they use this cache crop to feed themselves and their nestlings. Research has shown they have a phenomenal memory and can find most of the seeds they’ve stashed, even months later.

Most… but not all; some of the hidden seeds germinate, re-establishing the bird’s favorite trees in areas cleared by fires or logging operations. It’s a sustainable harvest practice, however accidental, and a form of basket-watching that would make Samuel Clemens proud.

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* The grosbeak taxa is a conglomerate of distantly related songbirds known as a polyphyletic (“of many races”) group that we’ll explore in greater detail in future NDN posts.

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© 2011 Next-Door Nature—no reprints without written permission from the author. Thanks to the following photographers for making their work available for use through a Creative Commons license: ehpien (northern cardinal); Conrad Kulper (rose-breasted grosbeak); Eugene Beckes (red crossbill); Steve Wall (male and female cardinals); Trisha Shears (2nd red-breasted grosbeak); Eugene Beckes (2nd red crossbill);and Jamie Chavez (Clark’s nutcracker).  Figure A was made available through WikiMedia by Shyamal and Jeff Dahl.  Bird song mp3s files are in the public domain.