Hot and cold

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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Start your day with a little 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: 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).

Social network

next-door nature, urban wildlife, wasps, yellowjackets

Love Facebook? You might want to thank a paper wasp (Photo: roadsidepictures, Creative Commons license)

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Mark Zuckerberg would not be one of 100 wealthiest and most influential people in the world without the help of wasps. I mean the six-legged kind (whether or not two-legged WASPs should get any of the credit is something for attorneys to discuss and will not be addressed here).

It’s a lengthy timeline but easy enough to follow*:

wasps to Facebook timeline

There you have it—no social insects, no social primates and, therefore, no need for a social network. When you think about it, Facebook isn’t just an online community. It’s a kind of virtual hive. You and Mark owe more to wasps that you may have ever realized.

next-door nature, wasps, mud dauberNot all wasps are gregarious, mind you. The majority of species, including mud daubers (Sphecidae), pollen wasps (Masarinae) and potter wasps (Eumeninae) are solitary. You know the type… quiet, poorly developed interpersonal skills, keep to themselves, rarely cause much trouble. A lot of them don’t even have stingers and they take the term “wasp-waisted” to extremes. We’ll respect their privacy, at least for now, and come back for a visit some other day.

Meanwhile, here in the U.S. we have two basic types of social wasps: paper wasps (Polistes spp.) and yellowjackets (Vespula spp. and Dolichovespula spp.). The two groups are often lumped together under the “hornet” tag, but the introduced European hornet (Vespa crabro) is the only true member of that Family found in North America.

With a few exceptions, wasps have two pairs of wings and can be distinguished from bees by that narrow waist (aka petiole) between the thorax and abdomen. The ovipositor (an organ used to prepare and position eggs) of a fertile queen becomes the stinger of an infertile worker females; males are not capable of stinging. Unlike honey bees (Apis spp.), wasps do not leave their stinger behind and are able to deliver multiple injections of venom.

Adult wasps feed on nectar and, as a result, can be classified as pollinators. Some social wasps are omnivorous, feeding on fallen fruit as well as carrion; yellowjackets are especially attracted to open garbage cans and dumpsters, drawn perhaps to the sweet, sticky spillage from nearly empty soda cans and bottles as well as other types of decaying leftovers.

next-door nature, wasp, yellowjacket

yellowjacket (Vespula germanica)

Wasps come in a rainbow of colors, including vivid yellows, metallic blues, and bright reds (keep this helpful rule of thumb in mind when interacting with insects—flamboyant wardrobes usually serve as a “don’t touch!” warning, backed up with some kind of poison or venom). Because they often share a brown or black and yellow color scheme, paper wasps are often misidentified as yellowjackets. I don’t want to encourage you to get up close and personal to make the identification and, luckily, there’s no need. The easiest way to tell them apart is by their nests.

Paper wasps and yellowjackets will nest in trees, under building eaves, in walls, and just about any other place that offers some protection from the elements. Both types of wasp use chewed wood fibers as the main construction material, even when building underground, as yellowjackets often do.

next-door nature, wasp, paper wasp, wasp nestPaper wasp combs attach with a single filament and consist of one tier of adjacent papery hexagonal brood cells for developing larvae. Each cell is open on one end  so you can actually see the contents, if you choose (but please keep a safe distance. Better yet, just look closely at the opening photo above). Typically, a mature nest contains 20-30 adults and rarely grows to more than 200 cells. Paper wasps usually attack only when they or the nest is threatened, but they are territorial. As an interesting aside, the northern paper wasp (Polistes fuscatus) has extremely variable facial patterns and recent research suggests their facial recognition abilities are similar to those of humans and chimpanzees (Pan spp.). Obviously, individuality affords some benefit, even among drones—so much for faceless anonymity.

Yellowjackets prefer to raise their young in a kind of fortress that looks more like what we would think of as a hive, with layers and layers of brood cell combs. The whole structure is completely enclosed with the exception of a single entrance hole. Queens establish new colonies each spring, often returning to the site of a previous nest (the location is identified by a chemical scent marker recognizable even to a first-year queen). However, if the structure is particularly well-protected from the weather—in the wall of a house, say—it may become a perennial nest, populated year-round. Yellowjacket hives may range in size from several inches (at the beginning of the colony’s history) to enormous structures measuring six feet or more and housing as many as 20,000 adult workers.

Wasp control is dangerous, especially for people who have heart conditions or known allergies to the venom, so it’s important to know what you’re dealing with before you take action. There’s a huge difference between avoiding 20 winged assailants and outrunning 20,000.  Moreover, yellowjackets tend to be more aggressive—they don’t give up the pursuit as quickly. [For more information on how to safely manage wasps, download a fact sheet courtesy Drs. Mike Merchant and Glen Moore of my alma mater, Texas A&M. Whoop!]

Don’t be too quick to declare war on wasps, though. In addition to their important role in plant pollination, nearly every pest insect species has at least one wasp species that preys or parasitizes it, making wasps a critically important natural biocontrol that benefit agricultural and even home gardeners. If that’s not enough to convince you to live and let live with wasps, when possible, image your life without social media!

I’m serious—next time you see some wasps congregating around your front porch, take a moment to say thanks… just before you blast the nest with with the hose, knock it down with a broom handle, and then grind it into the sidewalk with your shoe to be sure there are no survivors (don’t act all innocent with me—I can see that can of Hot Shot® behind your back).

When you’re finished, don’t forget to post about it on Facebook!

 

*NOTE:  As new discoveries are made, scientists continually discuss, argue, and refine our understanding of the evolutionary history of life on Earth.  I realize this timeline is simplistic but it is based on currently available research. My intention was to create a captivating introduction to a post on wasps by illustrating a connection between Zuckerberg, social networks, and the Vespidae Family. If you have a nit to pick about my portrayal of the fossil record and its accuracy—cut me a little slack, okay? I’m a writer and an urban wildlife biologist, not a taxonomist. Plus my beloved MacBook Pro died last week so I’m way behind schedule, stressed out, and in mourning (I did pull myself together long enough to purchased a new MacBook Pro and, I must say, it has been incredibly supportive as I struggle overcome my grief.)

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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: [starting from the top] roadsidepictures (paper wasp on nest); Malcolm Tattersall (mud dauber); Richard Bartz (yellowjacket on leaf); Bob Peterson (paper wasp nest in situ); and Jason Hollinger (yellowjacket nest).

Roadside attraction

wildlife and roads, wildlife watching, wildlife habitat

Roads are both a blessing and a curse for wildlife (Photo: Colleen Greene, Creative Commons license)

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Ever dreamed of going on a safari? Then fasten your seat belt, start the engine, and hit the road. Any road. I’ll bet you dollars to donuts—take the time to look and you’ll spy enough wildlife to satisfy, Bwana.

Sure, some of the creatures will be easier to spot than others… for the simple reason they’re no longer moving.  But I’m not proposing a road-kill road-trip. Trust me, the city streets, shady neighborhood boulevards, highways and byways offer plenty of opportunities for wildlife watching. Naturally, the species on display depend on the size of the road, its location, the season, time of day, and the speed limit.

wildlife and roads, vultures, wildlife watchingLet’s say your motoring down a divided highway, a conduit to and through the all-American suburbs. The big stuff (aka megafauna), such as deer, elk, moose, bears, and even coyotes, can be seen at 65+ mph (although not always in time to either admire or avoid them). Certain birds of prey, red-tailed hawks in particular, can be seen at both speed and distance due to their habit of hanging out high on handy utility poles to scout for snacks. Anything more petite will be visible only if it’s on the shoulder or trying to cross the road. Scavengers looking for a free lunch can be seen out on the open road day (crows, ravens, vultures) and night (opossums, coyotes). That meal ticket can quickly turn the diner into dinner for someone else… and so on.

wildlife and roads, wildlife watching, groundhogBeyond mowed blacktop borders, in the woods and taller grasses, you’ll find rabbits, foxes, raccoons, skunks, and groundhogs. Based on my own non-scientific observation, to improve your chances of seeing these meso– (medium-sized) species as well as small but brightly colored male songbirds in situ you’ll have to ease up on the gas pedal and let the speedometer drop to 35-45 mph, tops.

A bicycle (or even a horse if you have access to one) would probably set the right pace for a rider to notice mice and voles, lizards, turtles, frogs and toads, as well as female songbirds (who tend to have less flashy wardrobes than their ready-for-the-disco menfolk). The truly diminutive critters—insects, spiders, snails and slugs—are hard to spot at more than arm’s length so it’s best to set off on foot and plan for a leisurely pace if spineless quarry is your goal.  A general rule: the slower you go, the more you’ll see—that’s what makes the backroads more appealing for this kind of trip than a superhighway.

In poetry, novels, song, and cinema people often speak of the allure and romance of roads—the ones that calls us, the ones less traveled, the ones that go on forever, choosing between high ones and low ones. Wild animals rarely have access to books and mp3 players and RedBox kiosks, though, and I’ve never found them to be all that interested in popular culture… so what’s the attraction?

To build a road through a previously undeveloped area, the first thing that happens is clearing a swath of the existing plant community, be that trees and shrubs or grasses or cacti. Once the project is completed (or even while it’s still in progress) new plants begin to colonize the bare soil, creating a plant community that’s different from the surrounding landscape along with an edge where new and old meet.  Disturbing the soil stimulates the germination of seeds that may have sat dormant for a long time waiting for the right conditions. Soil may be brought in from somewhere else as part of the construction process along with seeds from plants that are completely novel in this setting.

wildlife and roads, wildlife watching, wildlife habitatSince the plants predict what kind of animals will be found in any ecosystem, the new habitat creates opportunities certain wildlife species will exploit… but in most cases it won’t be the species that were living happily in the pre-construction habitat. Edge species will colonize the area, often using the right-of-way as a travel corridor before and after the road is completed. Some organisms will hitchhike to their new home on and in the bodies of larger animals or even motor vehicles. Birds, bats, and flying insects will drop in from above. Wild things are always jockeying for space and there’s no such thing as a vacant lot in nature—at least, not for long.

wildlife and roads, wildlife watching, pronghornMake no mistake—roads are a significant cause of habitat loss and their presence is detrimental to many types of wildlife. For others, though, the resulting edge provides exactly what they need to thrive. This includes our most familiar next-door nature species. In fact, the reason blue jays, robins, white-tailed deer and other edge-loving species are so common in human communities is because Homo sapiens is also an edge-loving species. Our roads are simply one very conspicuous example of that fact.

The natural world is never static; it’s always in flux and each day there are new winners and losers.  Are roads good or bad for wildlife? It depends on the species. But there’s no doubt they are a boon for wildlife watchers.

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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: Colleen Greene (black bear); e_monk (black vulture); Matt Reinbold (groundhog); MoDOT Photos (edge habitat); Allan Harris (pronghorn).

Winter haven

Ladybugs (and their gentlemen) are good at finding building cracks and crannies, and will move indoors for the winter when they can (Photo: Brian Collette, Creative Commons license).

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Old Man Winter finally blew into my town earlier this week. I like sleeping with the window open slightly and he slipped silently past the softly snoring mini-blind sentry, fanning out across the bedroom carpet as a layer of gelid air ready to catch my bare feet off guard as they carelessly kicked back toasty covers and dove overboard to greet the day.

Talk about a rude awakening!

I felt the lurking chill in the knick of time. Knees pulled back, feet hovering just above the floor, I weighed a long to-do list and a wide-awake wire fox terrier, eager to empty his bladder and chase a ball, against the possibility that on this day, at least, the better part of valor might involve a temporary (but hasty) retreat. Not out of cowardice, mind you. No, no… I just needed a little time to regroup and marshal my endothermic resources while I searched for the socks I’d peeled off while snoozing. I figured it shouldn’t take more than an hour or so before I’d be ready to do battle with my frosty intruder.

Mulling over my options, I stared blankly at the bed linens… then suddenly my eyes flew open! I was seeing red, literally, and I felt the room grow instantly warmer. Turns out, Spring had snuck in on Winter’s coattails in the form of about a dozen cheery round beetles scattered across my brown and turquoise paisley comforter, each wearing a shiny cherry waistcoat strewn with black confetti.

We humans are a terribly fickle lot, aren’t we? Especially when it comes to insects. As a biologist and not completely reformed tomboy, it’s slightly embarrassing to admit this, but if I’d awakened to find nearly any other kind of beetles on my bed, I wouldn’t have dithered about whether to get up—I would have been in the next room before a thought could snake its way through my synapses.  But ladybugs? They’re as welcome as the Tooth Fairy!

It’s a completely arbitrary preference… one shared by many members of my species, but still. I don’t know why people like one kind of basically harmless bug and abhor most of the others. Maybe it’s their round, smiley-face shape, or perhaps it’s the wardrobe. Can you imagine wearing anything less threatening than polka-dots?

Apparently, it’s an almost universally appealing sartorial statement—the 5,000 species of coccinellids, as they’re known to entomologists, are found, and in most cases welcomed, around the globe. Cute can go a long way to win over a hominid, but if you really want to stack the deck in your favor, you should also spend most of your time snacking on a major agricultural pest. During their 3-6 week lifespan, a single ladybug can consume up to 5,000 plant-draining aphids, and suck up to farmers while they’re at it.

But humans aren’t the only threat this world has to offer, and there’s more than luck to that crimson coloring. Red means the same for both VW and biological beetles:  STOP! Some coccinellid species can spray a substance that’s venomous to other insects and some mammals. That’ll spoil a predator’s appetite! Or pop a ladybug in your pie-hole (after all, they do look like candy) and you’ll get a mouthful of alkaloid toxins and a bellyache to remember. This kind of learned aversion is called aposematism, and it’s one of several chemical warfare strategies employed by the insect nation against each other and all other comers. Sometimes, I guess, polka-dots are just a ploy.

Ladybugs come in other hues—yellow, orange, and pink, to name a few—but the palette is always conspicuous because, for negative reinforcement to work, you need to be easily and immediately recognized by your no-longer naïve predator. Bright colors work like a charm—for the population if not for every individual insect. Sure, ladybugs lose some percent of their brethren to the learning curve, but the needs of the many outweigh the needs of the few, or the one. Mr. Spock said it, so you know it’s true. Trekkie references don’t do it for you? Then how about Lord Tennyson, who eloquently described Mother Nature as:

So careful of the type she seems, So careless of the single life

This is not a one gender species, of course, but you wouldn’t know it by their handles—ladybugs, ladybirds, lady beetles, lady flies. In several countries they’ve even been granted a kind of exalted status, such as the Netherlands (“lieveheersbeestje” or “dear Lord’s animal”), France (“bête à bon Dieu,” same translation as the Dutch), and Ireland (“bóín Dé,” which means “God’s little cow”).

ladybug development stagesMetamorphosis is the name of the game among the six-legged set, and ladybugs are no exception. They start life as small, yellow, rice-shaped eggs usually deposited on the underside of leaves. When they hatch… well, I’m sure their parents are very proud, but these are not pretty babies. They don’t take after mom and dad until many awkward molts and a shrimp-like pupa stage have passed. But they do make themselves useful to humans even at this young age by chowing down on aphids, scale (Coccoidea), and mealybugs (Pseudococcidae).

Knowing this, I carried each and every winged ruby from my bedroom to my office and tucked them into the topknot of a 6’ dracaena plant near the window, out of sight and reach of a trouble-making terrier-boy.  I’m not a bug, and there are times when I’m not much of a lady either, but I know a safe harbor when I spy one—and how to stay warm when Blue Northers, Nor’easters, Alberta Clippers, and other cold winds blow.

I also know that in many cultures the appearance of this appealing little tank of an insect is considered to be good luck. Waking up to ladybugs in January? If there’s a better omen for a great New Year, I can’t imagine what it could be.

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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:  justmakeit (telephone cord); The Real Estreya (multicolors);Kim Flemng (eggs); Jack Wolf (larvae); Gilles San Martin (pupa); and Juergen Mangelsdorf (fingertip).

Yawn

arctic fox by emma j bishop cc

There’s nothing quite as contagious as a yawn* (Photo: Emma J. Bishop, Creative Commons license)

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Grab forty winks. Saw logs. For a species that’s habitually short on shut-eye, we humans sure have come up with myriad ways to talk about it. We also spend a lot of time and money studying sleep, or the lack thereof. Yet, in spite of decades of inquiry, researchers still don’t have a good fix on why we—and just about every other living creature—need to nod off.  We’ve had better luck trying to understand other unconscious states, especially those employed by certain non-human species to deal with hard times.

yawning prairie dog by SearchNetMedia ccWinter poses a critical challenge for animals who stay put rather than migrate to warmer climes. Thermoregulation requires calories, but many foods—especially fruits, nectars, vegetation, and insects—are scarce when the days are short. The ability to reduce one’s energy needs can be a life-saving adaptation. Hibernation does just that—it lowers an animal’s metabolic rate. If all goes well, this period of inactivity, which may last several days, weeks, or even months, depending on the species, will stretch stored energy reserves (aka body fat) long enough for the animal to survive until a greener season. “If” depends on many factors, such as the abundance of autumn food resources, the length and severity of cold days, and even the stability of the den site during repeated freeze-thaw-freeze cycles.

When a critter—let’s use the chipmunk (Tamias spp.) as an example—transitions into a state of hibernation, its body temperature drops to near freezing, breathing becomes so shallow as to be imperceptible, and the heart rate decreases dramatically, from 350 to 4 beats per minute.  Although we tend to think of hibernation as a season-long slumber, chippies and other hibernating rodents do wake up every few weeks to have a snack and take a potty break, even though these periods of activity, called interbout arousals, consume up to 90% of stored body fat. There are some champion nappers in this chisel-toothed group—including the groundhog (aka woodchuck, Marmota monax), who sleeps half its life away, setting the alarm for March when it heads to bed in September.

Other examples of sound sleepers include: insectivores like the European hedgehog (Erinaceus europaeus) and the tenrecs (Microgale spp.); the mountain pygmy possum (Burramys parvus)—the only hibernating marsupial; and the echidna (Tachyglossus spp.), a monotreme.  Biologist recently added the mouse lemur (Microcebus spp.) and the fat-tailed dwarf lemur (Cheirogaleus medius) to the hibernator roster; prior to this discovery, we didn’t have any examples from among the primates. Additionally, since winter temperatures in their native Madagascar may reach 86° F (30° C), it’s become clear that hibernation isn’t strictly associated with cold weather. Nor is it limited to mammals; a bird called the common poorwill (Phalaenoptilus nuttallii) snoozes through at least some of the snowy season.

yawning polar bear by Paul Davidy ccIronically, that most famous of North American sleep icons, the bear (Ursus spp.), is the subject of much debate. The question is whether or not they are “true hibernators.” Bears often spend far more time sleeping than the so-called “trues,” so what’s all the fuss about?  Well, this is going to sound like nit-picking, but here goes. First of all, a bear’s heart rate drops, but not quickly enough to suit some scientists. Also, while the number of heartbeats may go as low as 8 per minute, the average is closer to 50 per minute. Moreover, during this time the bear’s body temperature remains pretty close to normal. This is a handy little idiosyncrasy that, should the need arise, allows the animal to wake up fast… and often cranky—a fact Santa (and anyone else) should keep in mind when planning a mid-winter visit to the den.

Taking to one’s bed for months on end could be seen as a rather over-the-top response to a simple cold front. It smacks of swooning characters in English romance novels from the late 1700s. Frankly, it’s not everyone’s cup of tea, and many wild critters take a more measured approach. Torpor is the term commonly used to describe these shorter, less dramatic forms of dormancy, although, technically, hibernation and other types of suspended animation are really subsets of torpidity. Call it what you will, there are examples of “temporary hibernation” in all the Classes of vertebrate animals—mammals, birds, reptiles, amphibians, and fish—and it’s commonplace among the myriad spineless critters.

For some of the busiest bodies, torpor is a daily habit. Hummingbirds (Trochilidae), for example, have such a high metabolic rate that they need to ingest a steady stream of non-carbonated sugar water (i.e., nectar) during their waking hours or they’ll become hypoglycemic and are too exhausted to fly. Can’t fly? Can’t feed. It’s a vicious circle that will ultimately lead to the bird’s death without some kind of intervention. As you might imagine, this need to constantly refuel creates an enormous problem when night falls and these feathered perpetual motion machines must rest. Without some way to temporarily lower their metabolic rate, hummingbirds would never be able to get out of bed in the morning. Never fear—torpidity to the rescue!

rock dove yawning by Tatiana Bulyonkova ccSwifts (Apodidae), chickadees (Paridae), nightjars (Caprimulgidae), and doves (Columbidae) are just a few of the other avian species who go torpid under various conditions. Generally speaking, these birds are fruit-, nectar-, or insect-eaters, and they tend to be on the small side (less than 80g). The snowy owl (Bubo scandiacus), at 1600-2950g is one exception to this rule, and biologists recently added a second, when it was confirmed that the tawny frogmouth (Podargus strigoides) goes torpid during Australian winters.  Personally, I find these new insights into animal behavior thrilling, because they reassure me that what we know about wild creatures is still a drop in the bucket compared to what we don’t know—there are worlds upon worlds waiting to be discovered on this blue gem of a planet we call home.

yawning turtle by Michael Ransburg ccOf course, cold is not the only hardship wild things would rather sleep through. Periods of drought are just as serious a threat to survival, especially for aquatic and semi-aquatic species. When a lake, pond, or stream goes dry, the inhabitants need to dig in. Literally. Turtles and tortoises (Testudines), crocodiles (Crocodylidae), frogs and toads (Anura), salamanders (Caudata), and some crustaceans will aestivate (also spelled estivate)—a drought-driven form of hibernation. They sink down into the mud before it dries completely, sealing themselves in a mucous capsule until the rains come again. If ever there was a time to be glad you can absorb oxygen in the soil through your skin, this is it, because the air in your boggy bubble won’t last very long.

yawning snowy owl by Pat Gaines ccResearchers are intrigued by these alternate forms of sleep and how they might offer clues for solving a variety of human health concerns. Honestly, I understand their fascination but I don’t know how they stay awake long enough to collect any data. Just writing about dormancy has my eyelid feeling so… heavy. I guess it’s… time for…. me to turn… in.

…..Hit the  YAWN!  hay.

……….Catch some…..zzzzzzzzz

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*Pop Quiz:  How many times did you yawn while reading this? 😉

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There’s nothing quite as invigorating as finding a little Next-Door Nature in your email inbox—click the “subscribe”  link in the upper right-hand corner of this page and receive notifications of new posts!
© 2011 Next-Door Nature—no reprints without written permission from the author. Thanks to these photographers for making their work available through a Creative Commons license: SearchNetMedia (prairie dog); Pau Davidy (polar bear); Tatiana Bulyonkova (rock dove); Michael Ransburg (turtle); and Pat Gaines (snowy owl).

Skywriter

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writing spider with prey, Alan Howell © 2011 used with permission

The writing spider has a signature web that makes species identification easy (Photo: Alan Howell © 2011 http://www.starpathimages.com, used with permission).

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Look at your feet. You are standing in the sky. When we think of the sky
we tend to look up, but the sky actually begins at the earth.
~ Diane Ackerman, A Natural History of the Senses

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I got tangled up in pieces of the sky this morning. Not on purpose, mind you. It’s been unseasonably cool the past week so my aerobic exertions have moved from an indoor treadmill outdoors to a tangle of pathways that wrap around the surrounding neighborhoods.  My earbuds wedged firmly in place, the volume on my iPod turned up loud enough for the bass to create some nice cranial reverb, I walked  toward the road with my head already in the clouds.

I returned to Earth in a hurry, though, when I flew through a spider web strung between a PED XING sign and a maple branch. Come to think of it, the impromptu Elaine Benes dance moves inspired by contact with a cobweb made for a pretty good workout. Just not the one I’d planned.

The impact caused some turbulence in other plans as well; specifically, those of the writing spider (Argiope aurantia) I was destined to meet.  All I had to do was pull wisps of skywriting off my face, hair, and arms, and I was good to go. Charlotte faced a bigger clean up.

When people write in the sky, they use small, agile planes and a device that injects oil into the hot exhaust manifold, creating plumes of dense white smoke. It’s an inherently wasteful process and the results are ephemeral, to put it mildly; the message begins to blur within minutes.  Spider webs are longer lasting—about 24 hours or so—but my eight-legged barnstormer is heavy into recycling. She ate yesterday’s draft last night and used it as the raw material for today’s composition. She does this nearly every night, and it’s a task that takes hours to complete. Now, thanks to me, instead of resting in her hammock all day waiting for dinner to be delivered, she’ll be busy scribbling for the second time in 12 hours.

Her nom de plume comes from a set of silky zigzags resembling text that she inscribes through the middle of a circular insect sieve up to 2 feet in diameter. Known as the stabilimentum, because it was originally thought to stabilize the structure (Latin just makes everything sound so much more consequential, doesn’t it?), her writing now gets mixed reviews.  Some folks think insects are attracted to the bright lacing, the way they would be drawn to a flame or a porch light. Still others believe using a bold white font alerts large non-prey creatures to the presence of the web so they can avoid colliding with it. I realize I’m only one data point, but I’d like to suggest an exception to that second hypothesis:  It doesn’t seem to work all that well for bipedal mammals.

male and female writing spiderThese highly visible orb weavers can’t see very well themselves, but they are attuned to air currents and web vibrations. The male (0.2-0.35 in/5-9  mm) goes so far as to communicate with the much larger object of his affection (0.75-1.1 in/19-28 mm) by plucking and strumming the strands of her web. This tells her the caller is a fella, not a feast. Then again, he may be both. Foellmer and Fairbairn (2003) report that A. aurantia males “invariably” die within seconds of copulating, not because the female kills them, but as a form of sex-triggered suicide (the lengths some men will go to avoid post-coital cuddling!).

Skywriting at 7,000-14,000 feet aims to grab the attention of spectators on the ground, usually to sell them something. When it’s done at 2-8 feet of elevation, it’s intended to capture and hold groceries—in the form of aphids, mosquitoes, wasps, bees, crickets, grasshoppers, and even dragon- and damselflies—long enough to bag ‘em up.

An insect intersects with a web and the resident spider rushes to its side before an escape can occur. What happens next is gruesome, but that’s a bug’s life for you: a quick bite delivers paralyzing venom and begins to turn innards into soup (the substance is harmless to humans, by the way). Then, almost faster than the blink of an eye, spider feet are juggling the hapless intruder until it’s spinning like something out of Cirque du Soleil. When the stunt is complete she’s got a silk-wrapped burrito. Convenient, portable, and ready-to-eat… the perfect snack for a calligrapher who writes and walks on air.

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[Shot by Alan Howell, who was in the right place at the right time and had a point-and-shoot camera handy.]
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© 2011 Next-Door Nature— no reprints without written permission from the author. Thanks to Alan Howell of Star Path Images for generously granting permission to use his writing spider photo and video, and also to Matt Edmonds for making his image of a male and female   available for use through a Creative Commons license and by posting it on Wikimedia.

Points of Light

firefly in someone's palm

Fireflies, also known as lightning bugs, are as much a part of summer in some American suburbs as the smell of newly mown grass (Photo: Jessica Lucia, Creative Commons license)

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Walking through a nearby park at dusk the other night, I saw a single spark. Then another. Soon there were too many to count, hovering in the airspace between my chin and my ankles, lighting my way past the pond, the gazebo, and the tennis courts.

Who needs a time machine when you have memory to transport you to another place, another you? Those sparks must have kindled a few synapses, because suddenly I’m six-years-old again, running with my best friend Cindi through freshly mown grass that envelopes us in the signature scent of a suburban summer while staining the soles of our feet DayGlo green. Wild with excitement at being allowed to stay outside after dark, we’re relentless, ruthless, giggling predators intent on imprisoning lightning bugs in an empty Miracle Whip® jar.

If you live in the eastern half of the U.S., tell your neighbor or coworker you watched fireflies last night and see happens. I’ll bet you, dollars to donuts, their faces will soften and glow as if bathed in the bioluminescence of an impromptu nightlight. It’s Proust’s Remembrance of Things Past all over again, but with Coleoptera instead of cookies.

Firefly by Art Farmer, Creative Commons licenseThat’s right, they’re not flies and not technically bugs either. They’re beetles, a group that doesn’t usually garner much affection from the human race. Let’s face it—we like our non-human animals to have fur or feathers and large liquid simple eyes. If you can make your butt blink on warm summer evenings, however, folks are willing to see you in a new light.

Special organs in the abdomen convert oxygen and a compound called luciferin into a yellow or chartreuse glow. They’re quite good at this, by the way. Common incandescent light bulbs convert only 10% of an energy supply into light; the other 90% is emitted as heat. Fluorescent bulbs transform 90% of the energy into light but fall short of the nearly 100% efficiency of a firefly’s “cold” light.

As kids, we learn that fireflies flash to find a mate. What you may not know is that each species—and there are many different species in North America alone—has it’s own unique light show. This helps everyone pair up correctly. Males fly around broadcasting a kind of visual Morse code to the females hanging out in or near the grass. When a female spots a familiar pattern she flashes a response, then they signal back and forth until the male finds her.

Some flash patterns warn away predators who’ve come to associate an unpleasant meal with a specific blink beat. This doesn’t work with every predator, juvenile Homo sapiens being one obvious example.  Often, though, the biggest threat comes from a relative—some species are able to mimic the unique display pattern of their kin to trick the males and… well, use your imagination. Or, better yet, let Isabella Rossellini explain it to you.

Returning from a reverie of 1965 to present day, I had a vague sense of something missing. Then it hit me—I didn’t see a single child with a jar in pursuit of bobbing, weaving cold-light moonbeams!  I found this disturbing. Disheartening.

My own lifelong fascination with the natural world wasn’t sparked by National Geographic Specials about exotic creatures living halfway around the world (although, in time, those programs came to have an impact as well). There’s no doubt in my mind that my love of all things wild started as a toddler, sitting in my mom’s lap in the backyard watching cardinals grow bold with curiosity as she whistled their calls—Birdy-birdy-birdy! Cheer-cheer-cheer!—back to them. It blossomed because, as a grade-schooler, I was allowed to raise tadpoles in galvanized buckets, catch crawdads in plastic cups, tie thread-leashes to the legs of June bugs, and run after lightning bugs with mayonnaise jars.

Maybe, if I’d been walking through a subdivision, I’d have seen evidence that the spark that caught fire in me all those years ago still has a chance to ignite wonder in the up-and-coming generation. Maybe there are thousands of children darting across thousands of lawns after millions of flashing yellow lights all across the U.S.  I hope so.

But can we really afford to leave it to chance? I don’t think so. So do me a favor, would you? Find a kid you know. Pull an empty jar down from a cabinet shelf and poke some holes in the lid. Then go outside after dinner tonight, catch some fireflies, and light a spark.

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© 2011 Next-Door Nature— no reprints without written permission from the author. Thanks to Art Farmer for making his photo of a firefly in flight available through a Creative Commons license.

Thanks for noticing

praying mantis nymph

A tiny assassin riding on my wrist (Photo: Kieran Lindsey)

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“Oh look—you’ve got a visitor!”

Standing outside my front door, Bryan, pet-sitter extraordinaire, was in a better position to spot that wisp of green. But coming or going, I doubt I’d have noticed on my own. A habitual multitasker, I’m often doing one thing while thinking about the next three. Not the best frame of mind if you want to notice a recently hatched praying mantis nymph near your doorknob.

That one-inch explorer wasn’t missing much, I assure you. I leaned in for a closer look, but s/he had the advantage: two large compound and three simple eyes packed onto a triangular-shaped head that can—and did—swivel nearly 180 degrees.

Earth is home to more than 1,800 species of mantids. I’m pretty sure this youngster was a Carolina mantid (Stagmomantis carolina), the only species native to North America. As I’ve mentioned before, though, I’m not as familiar with the spineless members of the Animal Kingdom, so it could just as easily have been a European mantid (Mantis religiosa) or a Chinese mantid (Tenodera sinensis), both accidentally introduced to this continent about 100 years ago.

The common name derives from the front legs, which are usually folded into a position that someone interpreted as devotional. Devoted to dinner might be a more appropriate assumption. The spiked forelimbs are better suited to predation than piety, with reflexes so lightning-quick as to appear supernatural to the unaided eye. While they commonly feed on a variety of other insects, large adult mantids have been known to capture and consume hummingbirds and tree frogs. No wonder they are often mistakenly (yet accurately) called preying mantises.

praying mantis laying eggsUnlike the truly prolific members of the insect clan, mantids produce a single generation each year. Nymphs hatch in late spring or early summer and are fully grown by late summer. In autumn, females find a stick, a stem or even a building and deposit a frothy mass that hardens to protect the eggs inside. The adults die soon after, of old age or exposure, and the eggs overwinter in their protective case.

When the nymphs emerge they look like miniature versions of their parents and begin to search for something to eat. Often, the fastest food is a sibling—cannibalism is common in the insect world and mantids are no exception.

Survivors of the initial feeding frenzy disperse, blending into green and brown foliage so well you may have to take their presence on faith… unless one just happens to be drawn to the winged activity beneath a light near an apartment door, where s/he is easily visible to an alert, undistracted nature enthusiast.

The stairwell of my apartment building is shaded in the morning and, with only two simple eyes at my disposal, I needed more light. So I held out a stick, hoping this familiar substrate would help me coax the nymph to climb onboard. Instead, the little swashbuckler leapt onto my wrist like a pirate swinging from the rigging of a ship, and I was instantly transformed from a biologist into a boat for a tiny, curious captain in a prayerful pose whose head pivoted port and starboard as we sailed into the sunshine.

And I was thankful.

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© 2011 Next-Door Nature— no reprints without written permission from the author. Thanks to Larry Salveson for making his photo of a female mantis laying eggs available through a Creative Commons license.