Category Archives: mammals

Watchdogs

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I heard sharp calls piercing the air, even before I noticed the compound of earthen dwellings, and knew that sentinels had spotted me and my canine companion.

Last autumn, I spent some time in New Mexico. I lived there, between Albuquerque and Santa Fe, for nearly a decade about 10 years ago, and I’d been feeling nostalgic for the high desert, with it’s technicolor sunsets and scents of piñon smoke and roasting chiles. So I packed up the car, settled Dash into his travel crate, buckled my seatbelt, and drove west. I wanted to spend some time catching up with friends over pozole and stacked enchiladas, making a pilgrimage to my favorite spa, and watching for urban wildlife species that are notably absent from my current home-base in Virginia’s New River Valley.

The terrier-boy and I were walking along a suburban easement one afternoon, behind a neighborhood of faux adobe Pueblo Revival style homes, when the cautionary cries began to fly. The barked alarms were not coming from man’s best friends—the backyard pooch patrol was decidedly silent. Maybe they were on a coffee-and-donuts break, or just taking a siesta. All I can say is, residential security companies and neighborhood watch associations could learn a thing or three about vigilance and civilian defense from the citizens of a prairie dog community!Based on old cowboy movies, you might think a drive far beyond the city limit sign would be required to find a prairie dog town, but these southwestern  hobbits have adapted admirably to humans and our sprawling developments. I guess that shouldn’t come as a surprise—after all, we have a good deal in common. Like H. sapiens, prairie dogs (Cynomys spp.) are social mammals. Like people, they can and do organize for the common defense. And, similar to their bipedal neighbors, they’ve developed a sophisticated vocal communication system.

Despite their common name and distinctive bark, these watchful creatures are not canines, but a type of ground squirrel native to North American grasslands. There are five different prairie dog species found in the U.S., Canada, and Mexico: black-tailed (C. ludovicianus), white-tailed (C. leucurus), Gunnison’s (C. gunnisoni ), Utah (C. parvidens), and Mexican (C. mexicanus). While best-known for their namesake call, this burrowing band is no one-hit wonder.

According to research by Constantine Slobodchikoff, Professor Emeritus at Northern Arizona University, prairie dog calls vary based on the type of predator (e.g., coyote or domestic dog, hawk, snake, or human). They even construct sentences, complete with a form of grammar, to convey specific information about the approaching menace, including color, shape, size, speed, and direction. Not a generic “Danger, Will Robinson!” SOS, but a detailed threat assessment along the lines of “Heads-up everyone! There’s a short, square-shaped, white-furred dog and a medium-tall human wearing a blue Marmot fleece jacket approaching on foot from the southeastern quadrant!”

How did researchers learn to decode Cynamysian? (Hey, if you have a better name for the language of prairie dogs, I’m all ears.) By presenting an imitation predator and observing the call and response. For example, the alarm call for “diving hawk” causes all the prairie dogs beneath the flight path to dive for shelter, while those outside the path calmly stand and watch. When a sentry sounds the “coyote or domestic dog” call, everyone above-ground moves toward a burrow, everyone below-ground comes to the surface, and then they all stand near the entrances, rubbernecking. “Human,” on the other hand, must be the equivalent of “CODE RED!” because the whole damn town runs for cover.

Dr. Slobodchikoff found that prairie dogs create new calls to communicate with one another about novel objects. They even engage in social chatter that has nothing whatsoever to do with existential threats to individuals or society. This small talk has been harder to decipher, but I suspect it includes all the gossip greatest hits—friends and family, crushes and break-ups, insults and resentments.

The social nature of a prairie dog town may explain a cultural phenomenon I think of as the Cynomys Wave. This conspicuous (and apparently contagious) behavior, also known as the jump-yip, begins when a single resident spontaneously stands on its hind legs, stretching up and back as if beginning a sun salutation asana. Instead of chanting OOOMMM, however, the creature let’s rip with a high-pitched WEE-OO, similar to the infamous yell that ended Howard Dean’s presidential aspirations . Then, in a scene reminiscent of a circa 1977 football stadium, the whole town jumps up to do The Wave, squealing like demonic dolphins.

Some scientists have hypothesized the jump-yip has a territorial function, as in “Mine, mine, this magnificent mound of excavated soil is MINE, and don’t you forget it!” Others suggest it’s related to alarm calls, serving as an “All clear!” once a crisis has pasted. A definitive diagnosis remains elusive but, regardless of its true purpose, it is certainly attention-grabbing.

Humorous antics aside, not all humans are happy when prairie dogs move into the neighborhood. For example, the sort of person whose self-worth is tied to an manicured, emerald green lawn of putting green smoothness is unlikely to put out the welcome mat for any subterranean species.

Nevertheless, prairie dogs do provide an accidental altruistic service to the larger environmental community, including people: they act as khaki-furred “canaries in the coal mine” for a very specific zoonotic disease. When there’s a sudden die-off in the local prairie dog population, it’s a strong indication that plague (of bubonic fame) has come to town. In some states, Health Department personnel regularly visit prairie dog communities, sampling the burrows for fleas, which carry the Yersinia pestis bacterium. The blood-sucking insects are then tested for plague as a proactive management strategy.

The development of modern antibiotics have lessen the impact of plague on human populations but the disease remains devastating to prairie dogs, inflicting far more damage to the community than mammalian, avian, or reptilian predators. Knowing this, I can’t help but wonder if Dr. Slobodchikoff’s team ever discovered a unique alarm call for fleas.

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© 2018 Next-Door Nature. Reprints welcomed with written permission from the author. Thanks to Alan Howell of Star Path Images for granting permission to use his photo, and to those who made their work available through the Creative Commons license: Josh More, Larry Lamsa, Toshihiro Gamo, Thomas, and William Currier.

Treehuggers

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I’ve been called a treehugger more than once in my life, and while I know the comments weren’t intended as such, I always take them as compliments. As a sobriquet it’s both true and false: true, because I do spontaneously hug exceptionally handsome or venerable trees; and false, because compared to the practiced professionals who scamper up and down tree boles every waking hour of their lives, my embraces are too amateurish to qualify as authentic hugging.

Sure, as a kid I would climb trees and hang from the larger limbs by my knees. We had several sturdy silver maples in our yard and I loved spending time in these leafy hideouts. But there’s more to being a treehugger than practice. I simply don’t have the body to become world-class, or even marginally proficient. To compete with the Eastern gray squirrels (Sciurus carolinensis) in my neighborhood, whose arboreal acrobatics would make a Cirque du Soleil gymnast green with envy, I would need a significantly different anatomy.

For example, I would need to lose enough weight (and height) to allow the friction created by the pressure of my paws gripping a small branch to overpower gravity’s bullying attempts to push me rudely onto the ground.

A better sense of balance would also be necessary if I were to have any success as a legitimate treehugger. I’m not saying I trip over myself on a daily basis but, as friends and family can attest, when I do fall it’s Charlie-Brown spectacular… and usually on my face.

Tree squirrels, in comparison, are masters at controlling their center of gravity. This can be attributed, at least in part, because they can hold on equally well with both hands and feet.  Here again I’m disadvantaged, and I place full blame on evolution, my DNA, and whichever hominid ancestors of mine, after climbing down from a tree on an African savannah, decided that standing upright and using feet almost exclusively for the precarious task of bipedal perambulation was a much better way to go than remaining quadrupedal.

My filed and brightly polished toenails would have to go, replaced by strong, sharp claws that could easily pierce porous bark or hook onto an uneven edge (completely impractical for someone who wears socks and sleeps under a blanket, though). Whereas humans, including me, need at least three points of attachment when climbing, this adaptation allows squirrels to secure their position with only two attachment points, and to grasp new surfaces at angles most animals would find impossible.

Most important of all, I would need feet that can pivot on a swivel joint, allowing my ankles to rotate backwards so I could hang from nearly vertical surfaces.

If I’d been born a flamboyantly fluffy-tailed rodent then maybe, just maybe, I could latch on to a wrinkle in the tree rind and hang by my toenails while enjoying a leisurely acorn snack. Alas, ’tis the fault in my stars to peer ever and enviously skyward, my feet with their simple-hinge ankles planted on the firmament at the base of the trunk, and looked down upon with curiosity and pity (I assume) from the higher-ups.

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[Thanks to the photographers made their work available through the Creative Commons license: Mr.TinDC, Artful Magpie, JoeInQueens, and Jed Sheehan.  © 2017 Next-Door Nature. Reprints welcomed with written permission from the author.]

Wingsuit

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Southern flying squirrel (Glaucomys volans), © 2014 Peter Harrill, used with permission

Is there any non-human skill people covet more passionately than the ability to fly?

Understandably, early aviation experiments centered around mimicry of birds, complete with flapping arms that were usually covered in feathers. The Greek legend of Daedalus and Icarus is a familiar example, but plumage continued to be part of the trial-and-error approach through the first years of the 19th century, when a tailor named Albrecht Berblinger constructed an ornithopter and then took an ill-fated plunge into the Danube. Those daring young men with their dreams of flying machines… they just didn’t understand the concepts of thrust, lift, and drag, and they couldn’t let go of the idea that soaring requires feathers.

I guess Saturday mornings with Rocky and Bullwinkle were not a part of their childhood.

Skip ahead in the history books about two hundred years, during which heavier-than-air flight went from foolish fantasy to fleetingly airborne, to semi-reliably aloft, to acrobatic enough to decide the outcome of a World War, to commonplace as ~30,000 commercial flights per day in the U.S. in 2017.

And yet…

Aviation advancements and inventions during the greater part of the industrial age were about balloons and dirigibles and planes, i.e., aircraft; human beings remained firmly planted on terra firma unless they could climb inside or hang from some kind of apparatus.

It’s hard to point to a specific aeronautic adventurer as the first to see a flying squirrel, recognized the similarities with their fellow mammal, connected the dots, and think, “Eureka! A wingsuit!” But no one lucky enough to have seen one of these big-eyed nocturnal windsurfers could fail to notice the resemblance to the modern flying suits that have finally allowed human beings to fly free as a bird squirrel, unencumbered by gondola, scaffolding, or fuselage.

Of course, strictly speaking flying squirrels don’t really fly, and neither do the people wearing a wingsuit.

They glide.

The wingsuit mimics a flying squirrel’s patagium—loose folds of skin that span the space between forelimb wrist and hindlimb ankle on either side of the body. Spreading those limbs into a jumping jack X, the furry membranes stretch into a rectangular shape that allows the tiny BASE* jumpers to propel themselves into the air and then slide down the sky at a 30-40 degree angle controlled fall.

© 2008 Steve Collins, used with permission

A long, flat tail is critical for controlling that fall. Serving as a rudder, it allowing 90 degree turns around mid-flight obstacles. The tail is used for landing, too; on the approach, the tail is raised to an upright position while, at the same time, all four limbs move forward to form a kind of patagium parachute. Together, these actions create enough drag to tip the animal’s head and body up as it prepares for impact with a tree trunk or branches, a bird feeder, or a building.

Northern flying squirrel (Glaucomys sabrinus) © 2015 Jukka Jantunen, used with permission

The New World is home to three species of rodent flyboys and flygirls: Northern (Glaucomys sabrinus); the recently differentiated and designated Humboldt’s (G oregonensis); and Southern (G volans). There’s some range overlap between Northerns and Southerns, but the two species are relatively easy to distinguish. Northerns are larger, but the belly of the beasts provides a much more notable difference; the underside of a Southern flying squirrel is creamy white, while Northern flying squirrels are beige below with darker roots.

Humboldt’s flying squirrel

There’s range overlap between Northerns (found from Alaska to Nova Scotia down to Utah and North Carolina) and Humboldts’ (whose limit their travels from British Columbia down into southern California) as well. However, the two are close enough in physical appearance and behavior that it took an examination of their DNA before scientists realized earlier this year (May 2017) that they were looking at not one species, but two. Humboldts’ have been described as smaller and darker than Northerns, but the fact that it took so long for the former to be recognized as distinctive (Southerns were first described in 1758, Northerns in 1801) suggests to me that one would have to do a mighty up-close-and-personal examination to make a positive ID.

All three varieties of Glaucomys have one important feature in common: they’re more risk-averse than you might have assumed. Riding the wind wearing a wingsuit is a dangerous activity for humans — one severe injury for every 500 jumps, according to one study, despite advances in materials, design, and training — but it’s just another day in the life of a flying squirrel. That’s not to imply they never miscalculate a distance, or botch a landing, or are immune from injury (or worse), but they do have concerns beyond thrust, lift, and drag, or changes in wind speed and direction.

Which is why, immediately after sticking the landing, a flying squirrel will scurry quickly to their nest hole, or the other side of the tree, or at least toward a deeper shadow. BASE jumpers and skydivers rarely have worry about avoiding predators waiting in the wings.

[Thanks to the photographers who granted permission to use their photos, and to those who made their work available through the Creative Commons license: Richard Schneider, and Barbogast. The painting of Icarus and Daedalus is by Charles Paul Landon, and the drawing of a New World flying squirrel is by Charles Henry Dessalines d’Orbigny, currently in the University of Washington’s Freshwater and Marine Image Bank; both images are in the public domain. © 2017 Next-Door Nature. Reprints welcomed with written permission from the author.]

*BASE is the acronym that stands for the four categories of fixed objects from which one can jump: building, antenna, span (bridge), and Earth (cliffs).

Oddly Normal

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I don’t live far from the eclipse’s Path of Totality, but I decided to stay put just the same. I didn’t even order eclipse glasses. I know there will be plenty of great video to watch throughout the day, and since my sweetheart is a talented professional videographer, I feel like I’ve got that angle covered.  I want to focus on what’s going on down under, here on Earth.

In anticipation, I’ve been reading stories about how the event will impact wildlife. Every single one of these reports has focused on the “strange” animal behavior we can expect to witness as the day goes dark… and I find that very strange indeed.

What these experts are calling odd is considered completely normal activity when it happens each evening. And from the descriptions I’ve read about what to expect, assuming night is nigh would be a perfectly reasonable assumption for any creature—human or non-human—who doesn’t have a television or an Internet connection and, therefore, doesn’t know that the sun will be playing hide-and-seek with the moon for a little while today.

Humans tend to be less familiar with nocturnal species than the ones who are active during regular business hours. I think the eclipse is going to offer a chance to get to know our neighbors who work the night shift… kind of like a rerun of the National Night Out that took place earlier this month.

As the light begins to dim, creatures who are active during the day may start their usual bedtime routines.  Some diurnal birds will sing one last serenade to the daylight as faux-evening falls…

…some will hurry back to nests of eggs or chicks…

…others will congregate for mutual protection, as they do at the end of every day.

Birds who love the night life will wake, possibly feeling less than rested but still ready to boogie in search of an early breakfast (or late dinner, depending how you look at it).

Some wild mammals are active and visible during the day, including a fair number of rodents such as tree squirrels, groundhogs, prairie dogs, and chipmunks. I’m expecting the eclipse to be a great time to see mammals who are usually waking up just as I’m starting to wind down…

Insect musicians will surely want to set the mood with a tune or two.

Fireflies know a little night music calls for romantic lighting…

…and amphibians aren’t about to let the invertebrates steal the limelight!

As the skies brighten we’re also likely to have a second dawn chorus… but without needing to get up before sunrise! So don’t despair just because the eclipse will pass your part of North America by, or because you don’t know how to make and use a pin-hole camera (even after you Google’d instructions). There should be some amazing wildlife sights to see, right here on good ol’ terra firma.

 

[Thanks to the following photographers for making their work available through the Creative Commons license: Eric Kilby, Dan Dzurisin, Ingrid Taylar, Pat Gaines, Rachel Kramer, Will Wilson, Tony Oldroyd, Michael Eisen, Elizabeth Nicodemus, USFWS, tsaiian, David Huth, and Ingrid Taylar.  © 2017 Next-Door Nature. Reprints welcomed with written permission from the author.]

Hungry

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Terrier-boy transformed into a velociraptor before my very eyes!

We were walking along, minding our own business, when a momentary ruffling of leaves on the side of the pavement captured Dash’s attention and instinct took over…

head periscopes right…

ears swivel forward, nostrils flare…

field of vision narrows, eyes become lasers…

muscles tense into compressed springs…

in the pause between two heartbeats the chase is on!

 

AND…ended just as quickly by that damned ever-present leash. Grrrr.

 

Initially, I assumed Dash’s prey response had been triggered by a mouse or vole, maybe a chipmunk. Holding him back by the harness, I leaned in for a closer look without really expecting to see anything but fern and wood violet leaves; small rodents usually dive for cover when a predator is on patrol. They don’t risk a backward glance.

So I was surprised and delighted to see small, dark-bright eyes staring back at me from beneath an impromptu stone roof.  Not a rodent after all, but an insectivore. A northern short-tailed shrew (Blarina brevicauda) standing his ground against monsters (Dash and me) larger, in relative size, than a T-rex. Fearless!

Or maybe just hungry.

Thanks to an extremely high metabolic rate, the northern short-tailed shrew (let’s go with NSTS for the sake of brevity) has to eat every 2-3 hours to avoid starvation. That makes for a mighty motivated and efficient predator. I’ll bet you if an NSTS was invited to a screening of Jurassic Park, and saw how much time the velociraptors waste stalking kids in the kitchen, he’d be thinking, “Sheesh… amateurs!” Or maybe he doesn’t need to see the movie. According to the fossil record, shrew-like mammals arrived in time to observe real dinosaurs stomping around on planet Earth. Not this particular shrew of course, but it could be buried deep in his genetic memory.

Finding, catching, and eating earthworms, snails and slugs, spiders, insects, frogs and salamanders, mice and voles, along with some seeds and fungi, is a shrew’s full-time 24/7/365 job. Sometimes they even eat each other. All those meals add up to a daily grocery tab of three times the NSTS’s weight. Think of it this way: if Dash were a shrew, he’d need to eat nearly 65 lbs of food every 24 hours, and if I were a shrew I’d need to eat… well, it’s none of your business how much I’d need to eat.

This voracious consumer tips the scales, barely, at 15-30g (0.53-1.06 oz) but he and his kind are literally red in tooth (and only figuratively of claw). Unlike rodents, a shrew’s teeth do not grow continuously. One set of choppers has to last for their entire life, but red-toothed shrews (Soricinae) have helpful iron deposits that provide additional strength to the surfaces most subjected to wear and tear.

Insectivores are one of only three known living mammal Orders with member species that produce venom. The saliva of a NSTS can paralyze or kill prey, even some animals larger than itself. Nothing as large as a human or a dog, mind you, although the pain of a bite can last several days.

Toxic spit certainly comes in handy when it’s time to appease that insatiable hunger. But before you can bite your dinner, to immobilize or eat it, you have to find it. Often in low- or no-light conditions. Lucky for the NSTS, there’s this thing called echolocation. You would think, given how many terrestrial mammals live at least a partially subterranean life, echolocating would be a pretty common talent. You would be wrong. Only rats, the tenrecs of Madagascar, the solenodons, and three species of shrews, including the NSTS, are known to have this ability. Unlike bats (which, because they can fly, are not technically classified as terrestrial mammals), shrews use low-amplitude, multi-harmonic sounds rather than clicks. It appears these calls are used primarily to collect information about their habitat rather than to zero-in on a food source. Still, you can’t find your way to prey if you can’t find your way.

Even with venom and ultrasonic squeaks, life isn’t a picnic. NSTSs (and shrews in general) have a high mortality rate. Winter is particularly brutal, especially if the shrew in question doesn’t have enough cached food to carry it through the lean times, when mercury itself remains huddled in a bulb-burrow. Summer brings its own set of challenges; temperatures above 95°F (35°C) are deadly for shrews, causing the animals to shift their periods of above-ground activity, interfering with their ability to find their 8-12 square meals per day.

It goes without saying (but here I am saying it anyway) that even fierce predators are often prey as well. Shrews are no exception. Despite spending much of their lives hidden in subsurface tunnels, under leaves, leaf litter, and snow, NSTS become a meal, or part of a meal, for many species of fish, reptiles, birds, and mammals.

It’s a predator-eat-predator world out there and size isn’t everything. You’ve got to stay hungry. As the saying goes, it’s not the size of the dog in the fight that counts, it’s the size of the fight in the dog. Or the shrew. They’re still around, still hungry, and the only dinosaurs to be found are computer generated and animatronic.

I guess that settles any argument over who ruled on Isla Nublar, and who got voted off the island.

 

[Thanks to the following photographers for making their work available through the Creative Commons license: Gilles Gonthier, Goran tek-en, and snapp3r.  © 2017 Next-Door Nature. Reprints welcomed with written permission from the author.]

Near and Distant

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[Photo: Steven Crane, CCL]

African elephants (Loxodonta africana) aren’t usually considered an urban wildlife species but I’d come a long way and wanted to see them while I was in South Africa. The built environment just doesn’t have the amenities Earth’s largest living terrestrial mammal needs to feel at home.  Africa’s elephants prefer dense forests, woodlands, deserts, and even the transition zones between these biomes to urban canyons and suburban savannah. Lucky for me, this study abroad excursion included several days at the Shamwari Game Reserve near Port Elizabeth in the Eastern Cape.

[© Gil Sinclair 2013, used with permission]

I also had the good luck to meet some relatives of the elephant while in Cape Town.  The rock hyrax (Procavia capensis) has found it much easier to adapt to city living than its country cousin.  I suppose concrete looks pretty familiar when boulders are your preferred abode. It also helps when you look much less threatening to the human neighbors throughout the hyrax’s Middle Eastern, sub-Saharan, and southern African range than their towering relatives.

Up on Table Mountain, which overlooks the city, hyraxes were everywhere: scampering along the pathways, basking on benches, happily whistling to one another, and enjoying the sunset from rocky precipices. Ignoring humans while living alongside them can be a good survival strategy for urban wildlife, and the hyraxes showed little interest in the two-footed visitors… unless some tourist with a camera decided to force the issue. Attempts to get the affable-looking creatures to pose were met with low “bug off!” grunts.

[© Gil Sinclair 2013, used with permission]

The family resemblance certainly isn’t obvious at first sight but keep in mind that the genealogical tree branched out millions of years ago.  Let’s start with stature:   adult elephants stand 10-13 ft (3-4 m) tall at the shoulder and may weigh over 8 tons, while an adult hyrax measures up at about 8-12 in (20-30 cm) and tips the scales at a whopping 8-9 lbs (4 kg).

Elephants have very little hair while hyraxes are covered in short taupe fur and long guard hairs that function like a cat’s whiskers.  With their small round ears it’s easy to see how they could be mistaken for a large guinea pig (rodent) or pika (cousin to rabbits and hares). Maybe that’s why they have so many aliases; in South Africa they are called dassie (Dutch for badger) or klipdas (Afrikaans for rock badger), Swahili speakers know them as pimbi, and in the King James Bible they’re referred to as coney (Middle English and Anglo-French). Even “hyrax” is misleading, originating from the Greek word “hyrak” or shrewmouse.

Taxonomists know you shouldn’t judge a book, or a beast, by it’s cover. Look beneath the binding and you’ll find a different tail. Make that tale.  For example:

  • [Photo: Andy Withers, CCL]

    Hyraxes don’t have trunks but they do have small pointed tusks and can deliver a ferocious bite when cornered.
  • Like elephants, hyraxes have flat, hoof-like toenails rather than curved claws.
  • Both are social mammals; elephants live in herds of up to 100 individuals, hyrax colonies can have up to 50 members.
  • Both have long gestation periods (22 months for elephants, 7-8 months for hyraxes) and offspring are slow to reach maturity.
  • Elephant and hyrax newborns are precocial, relatively mature and mobile shortly after birth.
  • Both species employ cooperative care for raising young. Elephant calves are tended from birth by both their mothers and other females in the herd; and hyrax pups are greeted and sniffed by the entire colony the day after they’re born.
  • Females stay with the group their entire life; males disperse.
  • Male elephants and hyraxes don’t have a scrotum; their testes remain in the abdomen even after sexual maturity.

The differences between elephants and hyraxes are more than skin deep, too.

  • Elephants must drink up to 50 gallons of water per day; rock hyraxes can survive for long periods on just the water they obtain through their food (although they dehydrate quickly in direct sunlight).
  • Neither animal is a ruminant, but hyraxes have a complex three-chambered stomach; elephants have a simpler but less efficient digestive system.
  • Hyrax stomaches are filled with symbiotic bacteria that help break down plant material; elephants have to consume up to 300 lbs of food per day, in part because they aren’t able to extract much nutritional value from what they eat.

  • [Photo: Abri du Plessis, CCL]

    An elephant spends a good portion of each day filling its stomach with food and water; rock hyraxes are world-class loafers who are inactive 95% of the time.
  • Hyraxes have poorly developed thermoregulation compared to other mammals so they need to sunbathe for several hours each morning to warm up and won’t venture out of their shelters on cold or rainy days. Elephants have to work at staying cool; they don’t sweat or pant but their large ears help to dissipate heat and they’ve developed a temperature regulation strategy that involves storing heat during the day and releasing it at night, similar to camels and desert rodents.
  • Elephants have a sixth “toe” and their feet have large subcutaneous cushions that distribute weight and absorb mechanical forces; hyraxes have a more flexible foot with a rubbery pad in the center that can be raised to create a suction-cup for clinging to rocks and moving across slick surfaces without slipping.
  • African elephants have no natural predators as adults (they have a decided size advantage) but their calves are vulnerable to attack by lions, crocodiles, leopards, and hyenas. Hyraxes have many predators and, as such, they feed in a circle formation, heads facing outward, eyes scanning for danger.

I’m told that most tourists who have a safari on their bucket list focus on the iconic African Big Five — elephant, rhinoceros, Cape buffalo, lion, and leopard.  I’d be the first to agree they’re all worth seeing in their natural environment, with no bars or moats to limit your view. Or theirs. 

But I find celebrity tours less interesting than exploring on my own.  I like to switch to hyrax-time, wander through neighborhood, sit at a sidewalk cafe or bask on a park bench and watch the residents, human and non-human alike, go about their day. Taking note of what makes us different and all the ways we’re related, despite the distance. 

© 2017 Next-Door Nature—no reprints without written permission from the author (I’d love for you to share my work  but please ask).

Hot and cold

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next-door nature, urban wildlife, fence lizard

Everyone, even fence lizards and other ectothermic creatures, are feeling the heat these days (Photo: Bandelier National Monument, Creative Commons license)

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Temperatures across the southern half of the U.S. are soaring into triple digits, so I was trying to think of creative solutions to beat the heat when it hit me—why not become cold-blooded!

next-door nature, urban wildlife, fox squirrelAlas, my brain must have overheated. Once air conditioning allowed a cooler head to prevail I realized that what seemed like a brilliant idea while baking beneath a blazing sun is absolutely, completely, utterly impossible… and not simply because mammals cannot will themselves to undergo metamorphosis.

You see, technically there’s no such thing as a cold-blooded animal (unless you’re speaking metaphorically about someone who lacks emotion or empathy).  Or a warm-blooded animal, for that matter. Both terms are shorthand for the ways in which body temperature (aka thermophysiology) is controlled in different types of organisms.

Most mammals and birds are classified as endotherms (Greek: endon = within; thermē = heat). For these critters thermoregulation is an inside job, primarily by way of metabolic processes. Under extreme environmental next-door nature, urban wildlife, sunbathersconditions some physical mechanisms come into play, but not solar energy (at least, not directly). If the mercury plummets and the body’s core temperature begins to drop, muscles shiver to create warmth; if the core temperature starts to rise the body perspires to cool via evaporation. No sweat glands? Pant like a dog… or birds. All evidence to the contrary, since humans are mammals, swimsuit-clad sunbathers dozing in rows on a beach or poolside with icy drinks standing at the ready are, in fact, capable of maintaining a relatively constant body temperature.

next-door nature, urban wildlife, gray treefrogWhen an animal’s body temperature is strongly influenced by ambient conditions it’s an ectotherm (Greek: ektós = outside). Fish, amphibians, reptiles, and invertebrates rely on external heat sources to get their juices flowing, especially during the chillier seasons or cooler times of day. That’s why these animals can be seen basking on rocks, roads, and any other warmth-radiating surface. Then, when they can’t stand the heat they get out of the kitchen, retreating into shade, water, or underground to cool off (Sound familiar? We really are more alike than different).

Take-home message: mammals and birds are endotherms; invertebrates, fish, amphibians, and reptiles are ectotherms.

Except when they aren’t.

It’s the exceptions that make the rule, right? Let’s begin with the usual ectotherm suspects. According to one source, 2% of invertebrates are endothermic. Regrettably, the informant failed to name names but, in spite of the fact that spineless animals are not my strong suit, I did managed to chased one down—snails and slugs (Oops, that’s two… and “chased” may be overstating things).  Fish, being vertebrate species, are my regular beat so I can state with certainty that billfish (e.g., sailfish, marlins), tuna (Scombridae), one family of sharks (Lamnidae, including makos and whites), and one species of mackerel (Gasterochisma melampus) are endothermic… at least to some degree. I’ve yet to find a reliable report of an endothermic amphibian, but among the reptiles sea turtles exhibit both ecto- and endothermic traits.

next-door nature, urban wildlife, echidnaMoving along to the endothermic exceptions… Hummingbirds (Trochilidae), swifts (Apodidae), and common poorwills (Phalaenoptilus nuttallii) all experience periods of lower body temperature and metabolic rate; therefore, some biologists argue they have ectothermic traits. Additionally, there are mammals—certain rodents, a couple of lemurs, and many bats—that enter hibernation or estivation in response to low temperatures or drought, respectively. Then there’s the echnidna (Tachyglossidae), a “primitive” mammal from Australia that’s an ectotherm eleven months of the year and an endotherm during the month when it lays its eggs (Yes, eggs. If you like rule-breakers Australia is your Mecca. In the interest of time and space, though, we’ll have to save monotremes for another day).

What I’ve presented above is a fairly simplistic description of thermophysiology.  Why stop there? Because a more thorough treatment would require a good deal of nuance and a complicated discussion of sub-categories, not to mention a stiff drink (the current temperature is 99°F and rising—make mine a frozen margarita).  But since it’s so hot I’ll go ahead and venture past a toe in the water… up to my knees, but no further.

next-door nature, urban wildlife, elephant shrewOne subset of the endotherms are tachymetabolic (Greek: tachy = quick), organisms with a consistent and extremely high metabolic rate. Shrews (Soricidae) are a perfect example—diminutive beings with massive appetites, their metabolic rate is at least five times that of similarly sized ectotherms. Being able to snack non-stop and still rock a bikini probably sounds too good to be true. It is. Finding a constant supply of calories without access to fast food and grocery stores is no picnic. Bradymetabolic (Greek: brady = slow), which could easily be mistaken for bipolar disorder, is no bed of roses either. These organisms swing wildly between a high (when active) and low (when resting) metabolism, usually based on either external temperatures or food availability. (If you think someone else has got it better, rest assured you probably don’t know the whole story.)

As biologists refine our understanding of how bodies work, language evolves and once popular terms like cold-blooded fall from favor. Popular stereotypes suggest otherwise, but scientists are not completely immune to trends. When I was an undergrad, for example, the preferred word for organisms influenced by changes in ambient temperature was poikilotherm (Greek: poikilo = varied, irregular). Although still useful for making distinctions between types of ecotherms, the term is used less frequently now and may be on it the way out.

next-door nature, urban wildlife, crocodilesC’est la vie. Styles change, in both the lab and on the beach (Thankfully. I’m old enough to remember when Speedos were all the rage in men’s swimwear). I’d be willing to bet, though, that most Earthlings won’t give up sun worship any time soon. Chillin’ in a sunbeam feels too good, whether you need it or not (at least as long as there’s a pool nearby).

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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. Just ask first.). Thanks to these photographers for making their work available through a Creative Commons license: Bandelier National Monument (sunning fence lizard); Michael V. Flores (fox squirrel cooling down); Nick Papakyriazis (sunbathers); geopungo (gray treefrog); BohemianDolls (elephant shrew); and Jess Loughborough (basking crocodiles).

Prodigal sons (and daughters)

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next-door nature, mountain lion, cougar, dispersal, Midwest

Cougars are one of several predator species returning to historic ranges, even when they include highly developed areas (Photo: Wayne Dumbleton, Creative Commons license)

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Midwesterners are welcoming the return of some long-absent natives.

On second thought, “welcoming” is probably an overstatement… because just as in the famous biblical parable, not everyone is thrilled about this reunion.

A rigorous statistical study to be published in an upcoming issue of the Journal of Wildlife Management confirms the presence of 178 cougars (Puma concolor) in the Midwestern U.S. states of Missouri (10), Nebraska (67), North Dakota (31), Oklahoma (12), South Dakota (11), and Texas (12). Single incident reports were documented in Arkansas, Illinois, Iowa, Kansas, Louisiana, Michigan, Minnesota, and Wisconsin.

next-door nature, cougar, mountain lion, historic photo, market huntingOnce found throughout North America, from the Canadian Yukon south to the Chilean Patagonia and all 48 contiguous United States, cougar populations dropped precipitously over most of their historic range following European colonization of the continent. The 19th and early 20th centuries, in particular, were hard times for all wild predators. Eradication programs aimed at protecting livestock interests were common. Bounties for cougar pelts, combined with sport hunting and a reduced prey base, lead to extirpation of the species east of the Rockies, with the exception of a small subspecies population in Florida (the Florida panther, Puma concolor corryi).

You’ve heard of a coat of many colors? How about a cat of many names? Cougars are almost interchangeably known as mountain lions and pumas, but regional variants include catamount, panther, painter, ghost cat, screamer… and that’s just the English nomenclature.

The cougar has had more than it’s share of scientific names, too. Originally considered the largest member of the Felis clan, a genus that includes both the domestic cat (F. catus) and the somewhat larger jungle cat (F. chaus), in 1993 taxonomists created a new Puma group based on similar genetic structure and composed of two members—P. concolor and P. yagouaroundi, the much smaller jaguarondi, found in Central and South America. Another homecoming of sorts, I guess you could say, although whether the members are happy about their new blended family is anyone’s guess.

As the forth largest of all the world’s cats, adult cougars reach shoulder heights of between 24-35 inches (60-90 cm), nose-to-tail lengths of between 6.5-8 ft (2-2.4 m, females and males, respectively), and average weights of 100-150 lbs (42-62 kg; females and males, respectively).  It’s interesting to note that the closer a cougar lives to the equator the smaller it will likely be; the largest cougars are those found closest to the poles.

The species gets its name from the Latin word for “plain” or “one color” and that’s generally true for individual animals (as long as you ignore the lighter belly, throat and chin). At the population level there’s significant color variation, from golden to silvery-grey or even coppery-red. Cougar kittens don’t start out concolor—they are spotted with ringed tails but these markings fade as the youngsters mature.

next-door nature, cougar, mountain lion, dispersal, historic range, midwestAdult cougars have a sleek but muscular physique and are able climbers and strong swimmers, with exceptional leaping and powerful sprinting skills. Despite their speed, these cats are typically ambush predators that quietly stalk and then, if possible, drop silently down onto prey from above, breaking the neck or delivering a suffocating bite.

Cougars are obligate carnivores, which means to survive most of their calories must come from meat. What’s less important is whether the main course is mouse, squirrel, rabbit or raccoon, mutton, venison or veal. This failure to discriminate between wild game and domestic livestock has resulted in a long and bitter feud with ranchers that continues to this day.

The 1960s, however, were witness to a sea change in American attitudes toward the environment in general and predators specifically—at least in the urban and suburban areas that were rapidly becoming home to a majority of citizens. Public pressure to change management policies created greater legal protection for cougars and their numbers began to increase. Over subsequent decades, pressure to disperse has obviously increased as well, as western cougar habitat reaches carrying capacity.

Which brings us right back to where we started, with cougars recolonizing the center of the continent. They use what researchers call a “stepping stone” pattern. Young animals say goodbye to Mom (male cougars are absentee dads) and go looking for adventure. Travel the highways and byways, stop at an interesting locale, scout out dating and dining options then move along. Sometimes quite far along… as was the case with a male cougar who made it to Connecticut before being hit and killed by a vehicle.  Leaving home is what most young mammals, including humans, are programmed to do. I’m as good an example as any, having dispersed from Missouri at 21 to explore all three North American coasts and beyond.

next-door nature, cougar, mountain lion, dispersal, midwestCougars may have returned to their old stomping grounds but don’t expect fireworks or any other hoopla. As a native who left the area and has returned many times (although never to stay) I can assure you this homecoming will be a low-key affair.

We Midwesterners don’t like to call attention to ourselves, you know.

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Life is better with Next-Door Nature—click the “subscribe”  link in the upper right-hand corner of this page and receive notifications of new posts!

© 2012 Next-Door Nature—no reprints without written permission from the author (I’d love for you to share my work. Just ask first.). Thanks to these photographers for making their work available through a Creative Commons license:  Wayne Dumbleton (cover); USFWS/Public Domain (historic photo of a market cougar hunter); Anthonut (profile); Susan Shepard (climbing down); NaturesFan1226 (sharpening claws).