We are entering the heart of summer—those hot and humid days when the sweat flows freely and frequently, and noisy insects dominate the acoustical environment. All night long the crickets and katydids chirp away—providing a constant droning chorus of sound by rubbing various body parts (wings and legs) together. Their songs are trills, squawks, buzzes, and sometimes even pleasant bell-like tones.
The daytime sound field, however, is dominated by cicadas—incredibly loud noisemakers who are biologically unrelated to crickets and katydids. Their sound-producing mechanism is also dissimilar: located on the bellies of male cicadas are tymbals (even the name tymbal sounds garish), which are drum-like organs that vibrate by the contraction of his tummy muscles. The sound is amplified by resonators and membranes built into his gut, to produce a penetrating noise that would be envied by any heavy-metal guitar player who loves the shrillness of electronic distortion.
When I was a kid I would hear this piercing whine on hot summer days. It was so loud that I’d stop playing and look around, wondering what in the world that could be. An older kid told me that it was coming from the hot wires strung between telephone poles. I believed that tale for many years.
Three years after we moved out here to the country, we had an invasion of periodical cicadas. In our neck of the woods this incursion is expressed by the Linnaeus periodical cicada—often popularly and improperly dubbed 17-year locusts, because countless hordes emerge every 17 years and fill the air with their drone for a few weeks. About two inches long and sporting bulging bright red eyes, the periodical cicadas are a rather grotesque sight, and the woods echo with their hum. A few days after the invasion began, our dogs caught on to the fact that these bugs were a tasty source of protein and we’d laugh to see them dash across the yard and leap into the air to catch and consume one.
An amazing fact about these periodic cicadas is that in their nymph stage they remain buried underground, sucking on tree roots for 17 years. Then they all emerge within a week of each other. How do they count up all those years so accurately? Aren’t there a few who miscalculate and emerge at 16 or 18 years? Can you imagine their confusion, if they did? “Where is everybody?” It’s just another of nature’s wonders.
Friday, July 16, 2010
Wednesday, July 14, 2010
Sunday, July 11, 2010
Native Versus Non-native
We frequently hear the terms “native” or “indigenous,” referring to a people or a plant or an animal that are native to a place—i.e., were born or originated there. These terms are often used in conjunction with the contrasting or opposing terms “non-native” or “invasive.” In the deep past the migration of species was so slow that all living things were pretty much considered native, but now we humans are in constant and rapid movement throughout the world, taking countless flora and fauna with us, so that native species are continually encountering non-native competition—sometimes with tragic effects.
A native species is one that originated in a given location. It came into being (the root of the word native is the Latin word natus, born) in its indigenous place; it evolved there. In the evolutionary process, species last only if they find a niche and come into balance with many other species; i.e., settle into a complementary existence. Over time an equilibrium is reached, and if the environment remains stable for a while, the various native species maintain that cooperative network, wherein each of them fulfills a useful role.
A non-native species—once indigenous to its own locale—is one that migrates to a foreign place. It then finds itself in strange territory, looking for a niche to occupy. In doing so, usually one of three outcomes will happen: (1) it can’t fit in or compete and dies out, (2) it finds a niche and settles in (sometimes adapting and changing itself and its new home in the process), or (3) it enjoys a considerable advantage in its new locale (finding little competition there) and it runs amok. The third case is the one that often gets labeled “invasive species,” because it moves in, upsets the delicate balance, and takes over. Some examples of invasive species in the US are kudzu vine, gypsy moths, Dutch elm disease, house wrens, avian influenza, water hyacinth, zebra mussels, etc., etc.
This process of native and non-native species competing with each other is as old as life itself. Species have always migrated into new territory and found themselves competing against native critters. The difference lately is that the migration rate can now be at the speed of an airplane. Think of the recent worldwide spread of swine flu.
Thus indigenous species are constantly and suddenly being exposed to strange invaders, often at a very bad time for many of them: when their native environment is already under stress and being degraded. Even in the quite recent past species had the leisure of many thousands of years to adapt to the changes in their environment or the encroachment of competitive species. Now they are being assaulted far more often and being forced to deal with these changes in days and months, rather than eons.
One of the most threatening invasive species on Earth is Homo sapiens. We are indigenous only to Africa, yet we have spread to every corner of the globe—overnight in nature’s time scheme. In every case we’ve bested any native species we’ve encountered, driving many of them to extinction. The Americas once were home to dozens of mega-fauna species (mammoths, ground sloths, giant bears, etc.), that disappeared soon after humans arrived on these continents, thousands of years ago. Passenger pigeons once blackened the skies above North America, until people shot them into oblivion, a century ago. Australia was home to several species of giant flightless birds, until people migrated there, 45 thousand years ago and found them easy pickings. The list could go on for pages.
We humans have relentlessly altered our environment, often by rooting out native plant species, as we create vast areas of cultivated products. Some would say that this most invasive species of all is running amok. In every case in the past, when an invasive species has exploded its population far beyond a sustainable level, nature has eventually forced things back into balance. The invaders’ numbers precipitously crash—think invasions of locusts. The gypsy moth relentlessly marched south from New England in the 19th century, rapaciously attacking and killing native oak trees, until it finally got checked by a native species of fungus in the Middle Atlantic states, just a few years ago. The crash of an out-of-balance non-native species seems inevitable. I wonder what Mother Nature has in store for Homo sapiens.
A native species is one that originated in a given location. It came into being (the root of the word native is the Latin word natus, born) in its indigenous place; it evolved there. In the evolutionary process, species last only if they find a niche and come into balance with many other species; i.e., settle into a complementary existence. Over time an equilibrium is reached, and if the environment remains stable for a while, the various native species maintain that cooperative network, wherein each of them fulfills a useful role.
A non-native species—once indigenous to its own locale—is one that migrates to a foreign place. It then finds itself in strange territory, looking for a niche to occupy. In doing so, usually one of three outcomes will happen: (1) it can’t fit in or compete and dies out, (2) it finds a niche and settles in (sometimes adapting and changing itself and its new home in the process), or (3) it enjoys a considerable advantage in its new locale (finding little competition there) and it runs amok. The third case is the one that often gets labeled “invasive species,” because it moves in, upsets the delicate balance, and takes over. Some examples of invasive species in the US are kudzu vine, gypsy moths, Dutch elm disease, house wrens, avian influenza, water hyacinth, zebra mussels, etc., etc.
This process of native and non-native species competing with each other is as old as life itself. Species have always migrated into new territory and found themselves competing against native critters. The difference lately is that the migration rate can now be at the speed of an airplane. Think of the recent worldwide spread of swine flu.
Thus indigenous species are constantly and suddenly being exposed to strange invaders, often at a very bad time for many of them: when their native environment is already under stress and being degraded. Even in the quite recent past species had the leisure of many thousands of years to adapt to the changes in their environment or the encroachment of competitive species. Now they are being assaulted far more often and being forced to deal with these changes in days and months, rather than eons.
One of the most threatening invasive species on Earth is Homo sapiens. We are indigenous only to Africa, yet we have spread to every corner of the globe—overnight in nature’s time scheme. In every case we’ve bested any native species we’ve encountered, driving many of them to extinction. The Americas once were home to dozens of mega-fauna species (mammoths, ground sloths, giant bears, etc.), that disappeared soon after humans arrived on these continents, thousands of years ago. Passenger pigeons once blackened the skies above North America, until people shot them into oblivion, a century ago. Australia was home to several species of giant flightless birds, until people migrated there, 45 thousand years ago and found them easy pickings. The list could go on for pages.
We humans have relentlessly altered our environment, often by rooting out native plant species, as we create vast areas of cultivated products. Some would say that this most invasive species of all is running amok. In every case in the past, when an invasive species has exploded its population far beyond a sustainable level, nature has eventually forced things back into balance. The invaders’ numbers precipitously crash—think invasions of locusts. The gypsy moth relentlessly marched south from New England in the 19th century, rapaciously attacking and killing native oak trees, until it finally got checked by a native species of fungus in the Middle Atlantic states, just a few years ago. The crash of an out-of-balance non-native species seems inevitable. I wonder what Mother Nature has in store for Homo sapiens.
Friday, July 9, 2010
Tuesday, July 6, 2010
Mystery Bird—Part 2
A few weeks later a near-tragic incident finally led me to an answer. One afternoon we heard a bird blast hard up against a window (despite the branches in front of it!). I went out and found it lying in shock. I gently brought it inside, placed it in a box, and said a little prayer that it might recover. As we waited, I began to think about what kind of a bird it might be. I’d been focused on getting it quickly to the safety of the box and not inspecting it (it clearly was not one of our familiar birds).
My quick impression was that it might be a sparrow. It had the right coloring and size. While awaiting the hoped-for recovery, I got out my field guide. No, this was not a sparrow—its bill was much longer and narrower. Hmmm, I remembered that my Mystery Bird had a bill like this one. Could this be it?! I began to pour through the book, now focused on beak shapes. The only small species of bird with that type of bill is a warbler. We’ve never seen or heard of a warbler around these parts, so I’d been assuming that we had none. Besides, the book’s warblers seemed all the wrong color for the Mystery Bird.
But I continued looking through the lengthy warbler section. Way towards the end of the chapter, sort of hidden away, and not really looking like a warbler at all, was the Louisiana water thrush. It looked very much like the stunned bird. Well, a bird in the box is worth two in the bush, and now I had the opportunity to examine this guy closer. In a few minutes I could hear him recovering, telling me he wanted out of his box. I took him outside to let him go—not yet into the wild blue yonder, but into a clear plastic bag. With the field guide laid beside him, I was able to identify him as a Louisiana water thrush. I was excited. It seemed that maybe I had finally found my Mystery Bird. One more test: What was his song like?
Blessed be the Internet! I navigated my way to the Cornell Lab of Ornithology’s Website, did a search on the Louisiana water thrush, and clicked on a recording of its song. Bingo! That was it! This little guy was not an indigo bunting or a sparrow, but a member of the wood warbler family. Just to be sure, I clicked on the indigo bunting song. It was strikingly similar, but now that I could listen to them side by side, it was clear that the water thrush was my bird. Mystery solved!
This experience has given me the opportunity to ponder why I got so far off track the last couple of years. Had I somehow been led to page 350 of The Sibley Field Guide to Birds of Eastern North America three years ago, I wouldn’t have wasted so much time wandering down the indigo bunting blind alley.
It’s a good example of how we may be presented with a mystery, cast about for a solution, and then seize upon a handy but erroneous answer. It’s not hard to convince yourself that you have solved the puzzle and later even attempt to explain away contrary observations. All fields of human knowledge are replete with examples of faulty explanations of phenomena that people hang onto, long after they should be cast aside for something closer to the truth. I’ve written before of how the Catholic Church continued to insist that the Earth was situated at the center of the universe, after evidence to the contrary was available.
I had become convinced that my Mystery Bird was an indigo bunting. Although I tried to stick with that story, I at least kept my mind open to another answer. It took the water thrush’s bashing into the window to shake me out of my belief. I appreciate his hard-earned lesson for me. Now my challenge is to figure out why a Louisiana water thrush—which supposedly prefers habitat with flowing water—would take up residence in our dry neck of the woods. It’s one mystery after another.
My quick impression was that it might be a sparrow. It had the right coloring and size. While awaiting the hoped-for recovery, I got out my field guide. No, this was not a sparrow—its bill was much longer and narrower. Hmmm, I remembered that my Mystery Bird had a bill like this one. Could this be it?! I began to pour through the book, now focused on beak shapes. The only small species of bird with that type of bill is a warbler. We’ve never seen or heard of a warbler around these parts, so I’d been assuming that we had none. Besides, the book’s warblers seemed all the wrong color for the Mystery Bird.
But I continued looking through the lengthy warbler section. Way towards the end of the chapter, sort of hidden away, and not really looking like a warbler at all, was the Louisiana water thrush. It looked very much like the stunned bird. Well, a bird in the box is worth two in the bush, and now I had the opportunity to examine this guy closer. In a few minutes I could hear him recovering, telling me he wanted out of his box. I took him outside to let him go—not yet into the wild blue yonder, but into a clear plastic bag. With the field guide laid beside him, I was able to identify him as a Louisiana water thrush. I was excited. It seemed that maybe I had finally found my Mystery Bird. One more test: What was his song like?
Blessed be the Internet! I navigated my way to the Cornell Lab of Ornithology’s Website, did a search on the Louisiana water thrush, and clicked on a recording of its song. Bingo! That was it! This little guy was not an indigo bunting or a sparrow, but a member of the wood warbler family. Just to be sure, I clicked on the indigo bunting song. It was strikingly similar, but now that I could listen to them side by side, it was clear that the water thrush was my bird. Mystery solved!
This experience has given me the opportunity to ponder why I got so far off track the last couple of years. Had I somehow been led to page 350 of The Sibley Field Guide to Birds of Eastern North America three years ago, I wouldn’t have wasted so much time wandering down the indigo bunting blind alley.
It’s a good example of how we may be presented with a mystery, cast about for a solution, and then seize upon a handy but erroneous answer. It’s not hard to convince yourself that you have solved the puzzle and later even attempt to explain away contrary observations. All fields of human knowledge are replete with examples of faulty explanations of phenomena that people hang onto, long after they should be cast aside for something closer to the truth. I’ve written before of how the Catholic Church continued to insist that the Earth was situated at the center of the universe, after evidence to the contrary was available.
I had become convinced that my Mystery Bird was an indigo bunting. Although I tried to stick with that story, I at least kept my mind open to another answer. It took the water thrush’s bashing into the window to shake me out of my belief. I appreciate his hard-earned lesson for me. Now my challenge is to figure out why a Louisiana water thrush—which supposedly prefers habitat with flowing water—would take up residence in our dry neck of the woods. It’s one mystery after another.
Sunday, July 4, 2010
Thursday, July 1, 2010
Mystery Bird—Part 1
Identifying most of the birds who inhabit our locale has been a reasonably straightforward task. Everyone knows what a crow looks and sounds like—as well as an owl, or a whippoorwill. Other birds are not at all shy; they perch proudly out in the open—birds such as the cardinal, the chickadee, and the titmouse—so they are also easy to identify. A few others may stay pretty much out of sight, but they have a distinctive enough call that they can readily be identified—such as the wood thrush or the peewee.
Then there are the challenging birds to classify: those who keep out of sight and have a call that is not very distinct. They’ve tested me, but after a few years I managed to figure out most of them—such as the brown thrasher and Baltimore oriole. But the biggest challenge of all for me has been the Mystery Bird—who first appeared about five years ago. Well, he did not visually appear, but his attractive song floated through the clearing one day, and I knew immediately that this was a new bird for me, and one that I’d like to get to know. The Mystery Bird called from somewhere back in the woods. I tried to sneak towards him, but he’d stop calling and then wait for an hour or so, before beginning again. For a few months we played song tag—as I frustratingly tried to get closer, with no success.
In an attempt to identify him, I’d listen to my birdsong CD. Although his call sounded unique to me when I was outside, it was rather complex, and I’d quickly get confused listening to all the dozens of recorded songs that might be candidates. His seeming uniqueness quickly became buried in a mass of confusion. My frustration grew.
In the following year I got my first glance at the bird, from quite a distance. It was small—about the size of a titmouse. OK, that narrowed it down some—at least it’s not something the size of a crow. With this hint, I returned to my field guides, hoping to find some small birds that would fill the bill (no pun intended). But I was still stymied. I just didn’t have enough information to nail this bird down. My Mystery Bird remained an enigma. He kept singing away, almost as if taunting me.
Cruising yet once more through my recordings, I came upon the call of the indigo bunting. I’d once seen a bunting in the area, so they are around here and are the right size. The more I listened, the more I felt that the Mystery Bird had finally been revealed: it was a beautiful indigo bunting. But I still hadn’t gotten more than a momentary glance from a distance. Was the mystery really solved?
Well, not quite. Last year the bird seemed to be growing bolder and was coming even closer. One day I saw him land in a nearby tree and commence to sing out. That’s him! But wait a minute: this bird did not appear to be a dark bunting blue at all. In fact, he seemed to be dark brown, but he quickly flew off before I could get a good look.
Then this spring—after about four years of chasing after this bird—he became even more audacious. I spotted him in a nearby tree one day (his song once again clearly identifying him) and this time I could see no hint of blue. He was dark brown on top, with a brown-streaked, cream-colored breast. I ran for my field guide and looked up the indigo bunting. Was I wrong? Was it another species? Could it instead be a sparrow? The book showed me that the female bunting is not blue—in fact, she looks rather like the bird I had just seen. But how can this be? A female singing? I know that some female birds do call, but usually only sparingly. This bird was anything but sparing in its singing. Did the female indigo bunting sing? The puzzling questions seemed to multiply. It seemed as if I was back to square one, in my attempt to discern who this songster was.
Mystery finally solved next time…
Then there are the challenging birds to classify: those who keep out of sight and have a call that is not very distinct. They’ve tested me, but after a few years I managed to figure out most of them—such as the brown thrasher and Baltimore oriole. But the biggest challenge of all for me has been the Mystery Bird—who first appeared about five years ago. Well, he did not visually appear, but his attractive song floated through the clearing one day, and I knew immediately that this was a new bird for me, and one that I’d like to get to know. The Mystery Bird called from somewhere back in the woods. I tried to sneak towards him, but he’d stop calling and then wait for an hour or so, before beginning again. For a few months we played song tag—as I frustratingly tried to get closer, with no success.
In an attempt to identify him, I’d listen to my birdsong CD. Although his call sounded unique to me when I was outside, it was rather complex, and I’d quickly get confused listening to all the dozens of recorded songs that might be candidates. His seeming uniqueness quickly became buried in a mass of confusion. My frustration grew.
In the following year I got my first glance at the bird, from quite a distance. It was small—about the size of a titmouse. OK, that narrowed it down some—at least it’s not something the size of a crow. With this hint, I returned to my field guides, hoping to find some small birds that would fill the bill (no pun intended). But I was still stymied. I just didn’t have enough information to nail this bird down. My Mystery Bird remained an enigma. He kept singing away, almost as if taunting me.
Cruising yet once more through my recordings, I came upon the call of the indigo bunting. I’d once seen a bunting in the area, so they are around here and are the right size. The more I listened, the more I felt that the Mystery Bird had finally been revealed: it was a beautiful indigo bunting. But I still hadn’t gotten more than a momentary glance from a distance. Was the mystery really solved?
Well, not quite. Last year the bird seemed to be growing bolder and was coming even closer. One day I saw him land in a nearby tree and commence to sing out. That’s him! But wait a minute: this bird did not appear to be a dark bunting blue at all. In fact, he seemed to be dark brown, but he quickly flew off before I could get a good look.
Then this spring—after about four years of chasing after this bird—he became even more audacious. I spotted him in a nearby tree one day (his song once again clearly identifying him) and this time I could see no hint of blue. He was dark brown on top, with a brown-streaked, cream-colored breast. I ran for my field guide and looked up the indigo bunting. Was I wrong? Was it another species? Could it instead be a sparrow? The book showed me that the female bunting is not blue—in fact, she looks rather like the bird I had just seen. But how can this be? A female singing? I know that some female birds do call, but usually only sparingly. This bird was anything but sparing in its singing. Did the female indigo bunting sing? The puzzling questions seemed to multiply. It seemed as if I was back to square one, in my attempt to discern who this songster was.
Mystery finally solved next time…
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