Tuesday, July 12, 2011
Thursday, July 7, 2011
Pillbug Pervasiveness
We had a very wet spring this year—rainfall for April and May was twice normal. An abundance of rain in early spring rapidly changes the surrounding hues from winter's browns and grays to countless shades of green. It's a wonderful experience to see the growing season get such a watery boost and watch the garden vegetables luxuriate and flourish. The plants get so happy!
A wet spring causes many shifts in the balance of the local ecosystem, as compared to a dry spring. With lots of rain plants get a good season's start and insects abound, as they find many blossoms to visit. We'll be paying the price later, I fear, when mosquitoes and gnats will also proliferate. One of the unusual population explosions we've noticed this spring is pillbugs. These little terrestrial crustaceans, also known as woodlice or roly-poly bugs1, are always found in dark, wet spots. (Other delightful names are armadillo bug, doodlebug, roll-up bug, and chuggypig.) Since the wet spots have recently been everywhere, so have the pillbugs. Turn over a damp log and the bottom will be coated with these little guys. Lift some soggy mulch and bunches of pillbugs will scatter.
Pillbugs are in the family Armadillidiidae. Doesn't that make sense? A pillbug is about a quarter inch long, with 11 armored body segments. When threatened they roll into a ball, causing the critter to resemble a round little pill. This process is also known as conglobulation. (Doesn't that word just roll playfully off the tongue?) Kids call it roly-polying. These bugs also conglobulate when their environment dries up, to conserve water.
Pillbugs are one of nature's important agents for decomposing rotting wood and other decaying organic materials. They have even been kept by some people as pets—most often used to keep cages for rodents clean, by eating feces, mold, and discarded food. With that kind of diet we don't worry much about them causing any real harm, unless a bunch of them get into the strawberry beds and snack on the berries (it's their one sweet-tooth exception).
Every year is a little different in its particular mix of flora and fauna. Sometimes it's easy to ascribe and abundance (or lack) of a given plant or critter to the weather, but sometimes it also can be a mystery. If I keep a sharp eye out, maybe next year I'll solve a few mysteries.
A wet spring causes many shifts in the balance of the local ecosystem, as compared to a dry spring. With lots of rain plants get a good season's start and insects abound, as they find many blossoms to visit. We'll be paying the price later, I fear, when mosquitoes and gnats will also proliferate. One of the unusual population explosions we've noticed this spring is pillbugs. These little terrestrial crustaceans, also known as woodlice or roly-poly bugs1, are always found in dark, wet spots. (Other delightful names are armadillo bug, doodlebug, roll-up bug, and chuggypig.) Since the wet spots have recently been everywhere, so have the pillbugs. Turn over a damp log and the bottom will be coated with these little guys. Lift some soggy mulch and bunches of pillbugs will scatter.
Pillbugs are in the family Armadillidiidae. Doesn't that make sense? A pillbug is about a quarter inch long, with 11 armored body segments. When threatened they roll into a ball, causing the critter to resemble a round little pill. This process is also known as conglobulation. (Doesn't that word just roll playfully off the tongue?) Kids call it roly-polying. These bugs also conglobulate when their environment dries up, to conserve water.
Pillbugs are one of nature's important agents for decomposing rotting wood and other decaying organic materials. They have even been kept by some people as pets—most often used to keep cages for rodents clean, by eating feces, mold, and discarded food. With that kind of diet we don't worry much about them causing any real harm, unless a bunch of them get into the strawberry beds and snack on the berries (it's their one sweet-tooth exception).
Every year is a little different in its particular mix of flora and fauna. Sometimes it's easy to ascribe and abundance (or lack) of a given plant or critter to the weather, but sometimes it also can be a mystery. If I keep a sharp eye out, maybe next year I'll solve a few mysteries.
Monday, July 4, 2011
Friday, June 24, 2011
Bird Balladeers
It's common around here for us to hear several birds singing at once—especially in spring and summer, when they are declaring their territories, attracting mates, and just feeling good enough to croon and warble. Do birds sing for joy? Do they become energized by beautiful weather and unable to stop themselves from belting out a ballad or two? I don't think anyone knows if birds get excited about a pretty day and if it moves them to song. Regardless, I have decided that they are exhibiting some delight at just being alive. So I say they are singing out of genuine pleasure.
It's a delight to hear all the various bird ballads overlapping each other, as if they are in competition to see who can win the Avian Opus Award. It's an added bonus when I am able to watch a bird sing, while it is nearby. It's an uncommon experience, since most birds keep pretty quiet when a human is around. On those rare occasions when I'm close enough I can see its body swell up or its bill point to the sky, as it quivers during its burst of song.
Birds are literally built to sing. When we humans talk or sing, we use only about 2% of our exhaled air. Birds are far more efficient—they use virtually all of their out-breath. Our larynx is our voice box, which contains our vocal cords, the source of sound. Birds have a much more complex sound mechanism, that begins in what's called their syrinx. Just at the juncture of their bronchi (the two windpipes from their lungs) with the trachea, the walls of the syrinx have many tiny muscles that change its shape and generate their complex songs.
These muscles are so intricate that a bird can sing anywhere from a single note to a complex blend of harmonic multiple tones. In fact, some birds—the operatic thrushes, for example—can sing two songs simultaneously; sort of like a two-handed piano player, but with one throat! Try that sometime! The sounds that emanate from the syrinx muscles get further changed when a bird pulsates its throat or wiggles its head or bill. The result is an artistic concert that can't be beat.
Some 60% of all birds are true songbirds—the real melodic singers of the avian family. The remainder of birds don't really sing; they're quackers, screamers, croakers, cooers, squawkers, clatterers, and (bill) snappers.
Not only do we not know if birds sing from enjoyment, we are quite ignorant of how much information they communicate to each other when they make sounds. Sure, they may be declaring territory or wooing a mate, but they obviously send other kinds of messages that we can only guess at. There are subtleties to their language that we have yet to learn.
We humans tend not to give birds (or most any other animal) much credit for intelligence, because their simple vocalizations do not seem to have the range of meanings that our words do. But when birds who are able to imitate our words—such as parrots—learn a good number of words, we find them going on to construct simple sentences in creative ways. We tend to look upon this as a lower form of intelligence, when it's really not fair to judge their cognitive abilities on the basis of well they manipulate our language—something quite alien to them. How would space traveling beings from elsewhere look upon our mental capabilities, after we learn a handful of their “words” and then tried to use them to construct simple phrases?
Turn it around, and humans do a pretty poor job of making sense of animal language and forms of communications. It's pretty obvious from those who closely observe animals that their ability to communicate is very sophisticated, when we see how intelligently they respond to their environment. In fact, most of us can't even whistle the simplest of bird songs! And if we develop a rudimentary skill at it, we completely miss the nuances that birds easily pick up, such as regional accents, the age of the singer, the distance between them, how serious the caller is, etc. Birds not only can understand these details, but can discern the call of a close relative from among the simultaneous sounds of many birds of the same species—such as penguin parents locating their chick from among a crowd of hundreds. Is that not an exceptional skill?
While I recognize my ignorance of most of the meaning and message of birdsong, I still can thrill to their concerts and even imagine what they're saying. Although it may add to my deeper understanding if I were able to know who is the composer of particular strain of orchestral music I hear, I can still thrill to the sensation it brings to the back of my neck. A bird's artistry makes me pause in my work and become absorbed by the beauty of his song. And the more I listen, the more I hear and appreciate. I've got lots of listening to do!
[Some of the specifics of how birds make their songs I got from a neat little book by Barry Kent MacKay: Bird Sounds, 2001.]
It's a delight to hear all the various bird ballads overlapping each other, as if they are in competition to see who can win the Avian Opus Award. It's an added bonus when I am able to watch a bird sing, while it is nearby. It's an uncommon experience, since most birds keep pretty quiet when a human is around. On those rare occasions when I'm close enough I can see its body swell up or its bill point to the sky, as it quivers during its burst of song.
Birds are literally built to sing. When we humans talk or sing, we use only about 2% of our exhaled air. Birds are far more efficient—they use virtually all of their out-breath. Our larynx is our voice box, which contains our vocal cords, the source of sound. Birds have a much more complex sound mechanism, that begins in what's called their syrinx. Just at the juncture of their bronchi (the two windpipes from their lungs) with the trachea, the walls of the syrinx have many tiny muscles that change its shape and generate their complex songs.
These muscles are so intricate that a bird can sing anywhere from a single note to a complex blend of harmonic multiple tones. In fact, some birds—the operatic thrushes, for example—can sing two songs simultaneously; sort of like a two-handed piano player, but with one throat! Try that sometime! The sounds that emanate from the syrinx muscles get further changed when a bird pulsates its throat or wiggles its head or bill. The result is an artistic concert that can't be beat.
Some 60% of all birds are true songbirds—the real melodic singers of the avian family. The remainder of birds don't really sing; they're quackers, screamers, croakers, cooers, squawkers, clatterers, and (bill) snappers.
Not only do we not know if birds sing from enjoyment, we are quite ignorant of how much information they communicate to each other when they make sounds. Sure, they may be declaring territory or wooing a mate, but they obviously send other kinds of messages that we can only guess at. There are subtleties to their language that we have yet to learn.
We humans tend not to give birds (or most any other animal) much credit for intelligence, because their simple vocalizations do not seem to have the range of meanings that our words do. But when birds who are able to imitate our words—such as parrots—learn a good number of words, we find them going on to construct simple sentences in creative ways. We tend to look upon this as a lower form of intelligence, when it's really not fair to judge their cognitive abilities on the basis of well they manipulate our language—something quite alien to them. How would space traveling beings from elsewhere look upon our mental capabilities, after we learn a handful of their “words” and then tried to use them to construct simple phrases?
Turn it around, and humans do a pretty poor job of making sense of animal language and forms of communications. It's pretty obvious from those who closely observe animals that their ability to communicate is very sophisticated, when we see how intelligently they respond to their environment. In fact, most of us can't even whistle the simplest of bird songs! And if we develop a rudimentary skill at it, we completely miss the nuances that birds easily pick up, such as regional accents, the age of the singer, the distance between them, how serious the caller is, etc. Birds not only can understand these details, but can discern the call of a close relative from among the simultaneous sounds of many birds of the same species—such as penguin parents locating their chick from among a crowd of hundreds. Is that not an exceptional skill?
While I recognize my ignorance of most of the meaning and message of birdsong, I still can thrill to their concerts and even imagine what they're saying. Although it may add to my deeper understanding if I were able to know who is the composer of particular strain of orchestral music I hear, I can still thrill to the sensation it brings to the back of my neck. A bird's artistry makes me pause in my work and become absorbed by the beauty of his song. And the more I listen, the more I hear and appreciate. I've got lots of listening to do!
[Some of the specifics of how birds make their songs I got from a neat little book by Barry Kent MacKay: Bird Sounds, 2001.]
Monday, June 20, 2011
Tuesday, June 14, 2011
Vanishing Vultures
Few birds elicit more contradictory responses than the turkey vulture. Spot one soaring gracefully overhead and you'll likely respond with, “Ooh, look at that! Isn't it stunning?” Spot one alongside the road, feasting an a dead carcass and you're more likely to respond with, “Yuck! What a revolting sight.”
The turkey vulture is widespread across the US, and is an important bird. Like the dung beetle and the maggot, the vulture plays a major role in nature's recycling system. Still, we'd much rather watch a songbird daintily peck at seeds than see a vulture picking over the decaying carcass of roadkill.
They have eyesight nearly as acute as eagles and can spot carrion from high in the air—although they are also one of the few birds who have a keen sense of smell. Their version of an enticing fragrance, however, does not emanate from flowers. And vulture babies are even more revolting—they eat their parent's regurgitated spoiled food: tainted vulture vomit!
Vultures are big birds... well, really quite smaller than the resident feathered friend on Sesame Street. They are nearly the size of an eagle, with a wingspan of almost six feet. When gliding overhead they can be mistaken for a hawk. Years ago I was easily confused, but slowly learned to readily distinguish between them. The underside of a vulture's wings is dark, while a hawk's is nearly white. While the hawk's head is large and fierce looking, a vulture's head is tiny and naked, and almost appears headless at a distance. And if the glider emits any kind of shrill call, it's a hawk. Vultures are very quiet birds—as if not wanting to attract attention to their repellent sight.
On the ground the turkey vulture—as its name suggests—resembles a wild turkey, with both of them sporting a bare pate. The turkey's baldness helps it to cool down, while the vulture's naked noggin allows him to dive deeply into the innards of his meal and not have to clean feathers later (or, heaven forbid, have to endure the bad smell and unsightly appearance of crusted feathers).
The resemblance between them, however, stops with the bald head. If the bird has a neck, it's a turkey. The vulture's tiny bean needs little neck to support it. If it walks pertly along, it's a turkey. Vultures hop and waddle like a drunkard. But if you see the bird has whitish legs, you know it's a vulture—they have the revolting habit of squirting their liquid feces on their legs, because the evaporating liquid cools them. But then again, maybe they prefer the aroma.
I don't think many people would want a vulture for a pet. It makes me wonder, given that they are are an exception in birddom with their sense of smell, how they can stand their own stink. But I guess that's true of all of us. The other guy's farts always smell worse than ours.
Another interesting fact about the turkey vulture is that it has been slowly migrating northward in the US. A recent article in Living Bird magazine from Cornell University's Lab of Ornithology describes this phenomenon. A century ago Virginia was the northern extent of their territory. Now they can be seen well up into Canada. Why the movement north? Researchers are not certain. There could be several possibilities. First, climate change is forcing many species to head towards cooler territory. Second, some birders think the overpopulation of deer in the Middle Atlantic states and New England might be drawing the vulture in, as cars create an increasing number of deer carcasses roadside. Third, half a century ago DDT was widely used in the South, causing many birds to weaken. Now that southern vultures are more healthy and more populous, some might be foraging farther north for carrion.
Fourth, southern farms have slowly transformed from small livestock homesteads—where dead cattle were left in the field to the vultures and other scavengers—to today's large vegetable enterprises, with few cattle. Additionally, contemporary farmers can use their tractor to rapidly bury an expired cow or call the local rendering plant, rather than labor for a couple of days digging by hand, as the old timers had to do. And what busy farmer was going to be able to afford that much time, just to bury a useless cow?
Several years ago I had a neighbor tell me that he feared for the survival of the turkey vulture—although he called them buzzards. Now that farmers were no longer leaving dead livestock in the fields, he worried that vultures would become extinct. I was rather skeptical of his concern—partly due to my ignorance of the fact that farmers were now properly disposing of dead animals, but also because scavengers (think coyotes and crows, as well as vultures) are very resourceful creatures. Now that I know better, thanks to Cornell, I could console my neighbor by telling him, “It's OK, George, they're doing fine, they're just headed north.” In fact, the turkey vulture opportunistically dines on many other dead critters than cows and deer. I think there will be plentiful roadkill around here to keep the vulture soaring overhead (“Ooh! Isn't that stunning?”) for some time yet.
The turkey vulture is widespread across the US, and is an important bird. Like the dung beetle and the maggot, the vulture plays a major role in nature's recycling system. Still, we'd much rather watch a songbird daintily peck at seeds than see a vulture picking over the decaying carcass of roadkill.
They have eyesight nearly as acute as eagles and can spot carrion from high in the air—although they are also one of the few birds who have a keen sense of smell. Their version of an enticing fragrance, however, does not emanate from flowers. And vulture babies are even more revolting—they eat their parent's regurgitated spoiled food: tainted vulture vomit!
Vultures are big birds... well, really quite smaller than the resident feathered friend on Sesame Street. They are nearly the size of an eagle, with a wingspan of almost six feet. When gliding overhead they can be mistaken for a hawk. Years ago I was easily confused, but slowly learned to readily distinguish between them. The underside of a vulture's wings is dark, while a hawk's is nearly white. While the hawk's head is large and fierce looking, a vulture's head is tiny and naked, and almost appears headless at a distance. And if the glider emits any kind of shrill call, it's a hawk. Vultures are very quiet birds—as if not wanting to attract attention to their repellent sight.
On the ground the turkey vulture—as its name suggests—resembles a wild turkey, with both of them sporting a bare pate. The turkey's baldness helps it to cool down, while the vulture's naked noggin allows him to dive deeply into the innards of his meal and not have to clean feathers later (or, heaven forbid, have to endure the bad smell and unsightly appearance of crusted feathers).
The resemblance between them, however, stops with the bald head. If the bird has a neck, it's a turkey. The vulture's tiny bean needs little neck to support it. If it walks pertly along, it's a turkey. Vultures hop and waddle like a drunkard. But if you see the bird has whitish legs, you know it's a vulture—they have the revolting habit of squirting their liquid feces on their legs, because the evaporating liquid cools them. But then again, maybe they prefer the aroma.
I don't think many people would want a vulture for a pet. It makes me wonder, given that they are are an exception in birddom with their sense of smell, how they can stand their own stink. But I guess that's true of all of us. The other guy's farts always smell worse than ours.
Another interesting fact about the turkey vulture is that it has been slowly migrating northward in the US. A recent article in Living Bird magazine from Cornell University's Lab of Ornithology describes this phenomenon. A century ago Virginia was the northern extent of their territory. Now they can be seen well up into Canada. Why the movement north? Researchers are not certain. There could be several possibilities. First, climate change is forcing many species to head towards cooler territory. Second, some birders think the overpopulation of deer in the Middle Atlantic states and New England might be drawing the vulture in, as cars create an increasing number of deer carcasses roadside. Third, half a century ago DDT was widely used in the South, causing many birds to weaken. Now that southern vultures are more healthy and more populous, some might be foraging farther north for carrion.
Fourth, southern farms have slowly transformed from small livestock homesteads—where dead cattle were left in the field to the vultures and other scavengers—to today's large vegetable enterprises, with few cattle. Additionally, contemporary farmers can use their tractor to rapidly bury an expired cow or call the local rendering plant, rather than labor for a couple of days digging by hand, as the old timers had to do. And what busy farmer was going to be able to afford that much time, just to bury a useless cow?
Several years ago I had a neighbor tell me that he feared for the survival of the turkey vulture—although he called them buzzards. Now that farmers were no longer leaving dead livestock in the fields, he worried that vultures would become extinct. I was rather skeptical of his concern—partly due to my ignorance of the fact that farmers were now properly disposing of dead animals, but also because scavengers (think coyotes and crows, as well as vultures) are very resourceful creatures. Now that I know better, thanks to Cornell, I could console my neighbor by telling him, “It's OK, George, they're doing fine, they're just headed north.” In fact, the turkey vulture opportunistically dines on many other dead critters than cows and deer. I think there will be plentiful roadkill around here to keep the vulture soaring overhead (“Ooh! Isn't that stunning?”) for some time yet.
Sunday, June 12, 2011
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