The Sounds of Silence, the Price of Light

We live, most of us, in islands that have forgotten both silence and darkness. Although the earth still contains vast areas of both, more than half of humanity now lives in cities. In the industrialized world, far more than half of us live in large cities. The American West, that icon of individualism, sparse plains, and empty mountains is the most urbanized part of the United States. By 1990, 80% of all the people living in the American West lived in metropolitan areas. In eight of those states, the city population exceeded 88%! By any measure, westerners are city folks by a much higher percentage than anyone else in the United States.

And, in the places where most humans now live, it is never silent; never dark.

The Myth

Some mammals and some birds have adapted to the light and noise. Pigeons, Starlings, English Sparrows, House Finches and rats all thrive in our environment. Others avoid us – please pardon the cliché that is coming – like the plague.

There is no use in decrying this urbanization of the species; we have evolved to it and it must be adaptive or we would not have thrived as we have. Nor is there any reason to suppose the trend will ever reverse itself.

The Reality

We live in a transitional era. Still close enough in time to the jungle and savannah from which we came, we vaguely remember both silence and darkness. Recent studies have proven that we sleep sounder in absolute darkness and relative silence. We still fear the dark. We still yearn for a piece of nature. Anthropologists explain our little bits of lawn and garden – tyrannized nature – as remembrances of time past.

And, let’s face it, it is probably why so many of us are birders. We yearn to spend at least a little time in beauty, surrounded only by the sounds of wildness. Serenity lies in silent places and where better to find it than in a place where a bird call can lose itself in the silence of the world.

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For more on the urban American west, try the blog of the well-known western scholar Carl Abbott. His book, How Cities Won the West: Four Centuries of Urban change in Western North America is a good read and still available on Amazon. Any of the works of my American West professor, Gerald Nash are excellent introductions, especially his The American West Transformed: The Impact of the Second World War.

For those of us still gamely hanging on to the value of wild experiences, see this post at Wild Resiliency.

Attila the Hum

Rufous Hummingbirds have returned to our backyard and the Black-chinned Hummingbirds are not altogether happy about it. To say that a Rufous vigilantly protects whatever feeder or feeders it chooses to protect is an understatement, like calling Attila the Hun, “irritable.”

The backyard is livelier now.

Talking Penguins

It’s a bit of a stretch to get Rooster Cogburn into this birding blog.  True, the name “Rooster” also applies to a bird, but more is needed. Adding penguins might do it. How about penguins quoting Rooster from “True Grit”, a classic movie which, we are told has recently been shot again? That seems like a travesty:  How could anyone parody John Wayne as well as John Wayne?  Sadly, it was my daughter who told me that a movie production company was filming what she called “a new movie.” All I got was a blank stare when I told her it is not new at all.

On to the penguins. . . .

The Mockingbird Problem

We’re back from a birding/fly-fishing trip and will now finally address The Mockingbird Problem. Northern Mockingbirds – and about twenty percent of other passerine songbirds – are mimics. They steal their songs from their environments. Imagine the smartest student in class unnecessarily cheating on tests by going around the room and copying little bits of every other student’s answers.

That makes no sense. Instead of getting an “A” on the test, the student would get an “F” because her answers would be gibberish. Yet mockingbirds – obviously the star students in avian music class – do precisely that. Rather than develop their own unique songs, they just copy bits and pieces of the songs of other species.

Why?

Wouldn’t it be easier and less costly to invent their own songs and pass those down to their offspring? Less brain power would be required and learning would be simpler. Besides, the mockingbird isn’t fooling any other birds. They all recognize that the mockingbird isn’t one of them.

Nobody knows. We think we know that they sing for the same reasons as other birds: the males are seeking, stimulating, and keeping mates and they are competing with one another for mates and territories. But no one knows why they evolved singing songs of other birds. The same question can be asked about other mimics such as Common Starlings, Marsh Warblers, Australian Lyrebirds, bowerbirds, scrubbirds, and African Robin-chats.

Chihuahan Desert Mockingbird Locale (Otero Mesa)

We’ve learned a lot about Mockingbird song in the last century though. We know, for instance, that both males and females sing, although females sing only in the summer and only when their mate is off their territory. The males sing most in Spring, less in summer, still less in Autumn and hardly at all in winter. Unmated males sing more than mated males and will, in spring, sing all night long. (I’ve camped on the Chihuahuan Desert and listened to one sing all night long. That mockingbird may have been lonely, but he provided me with one of my favorite backpacking memories.) Unmated males sing in all directions, while mated males tend to sing inward toward their own territories.

Darwin's Mockingbirds

The males possess two entirely different repertoires, one for the spring and another for autumn. One had 203 songs in his mind. Somewhere between 90 and 150 seems about average. They continue to learn new songs for as long as they live. Older birds have larger repertoires than younger ones. Males with the most varied songs may get the largest territories. They may also mate earlier. And they sing all the time during breeding season, warbling away while copulating, eating, and foraging.

And probably they sing silently while dreaming. We know that Zebra Finches dream in song; no reason to suspect a bird that devotes as much of its cranial capacity to learning and remembering complex songs wouldn’t also dream in song.

They sing more during full moons.

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For more on Northern Mockingbird song see:

Derrickson, K. C. and R. Breitwisch. 1992. Northern Mockingbird (Mimus polyglottos), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/007

doi:10.2173/bna.7 (Subscription Required)

Frank Gill, Ornithology (3^rd ed.), pp 230-231 and 237.

For a sample song, try this: http://www.birdjam.com/birdsong.php?id=4

The photo of the Northern Mockingbird at the top is by Manjithkaina, used via a Creative Commons license.

Momentary Mockingbird Delay

We promised last time to continue our study of bird song with a post about “The Mockingbird Problem.”  We lied. Exigencies of the day jobs have forced a delay. To keep you interested though, here is a photo which is in the public domain thanks to the photographer, of a Northern Mockingbird chick, deciding whether to sing or not.  We’ll be back with the promised post shortly.

Why Do Birds Sing?

The short answer is, they sing to live. But that doesn’t tell us much. It is not a testable hypothesis and is at too high a level of generalization to be helpful.

And before we go any further, we pause to note that we are talking about bird song today, not bird calls. Calls are the comparatively simpler sounds made by birds to stay in contact with one another, to call for mobbing behavior, or to sound alarms. (Alarm calls, by the way, tend to be high-pitched calls which make the source of the sound harder for a predator to find.) Today we are talking about the more complex, difficult, and – to our ears, anyway – melodious songs of the passerines and other birds that sing.

Birds produce song by forcing air through the syrinx, a bony structure at the bottom of the trachea. The syrinx resonates sound waves generated by the vibrating membranes of the syrinx. Changing the force of the air controls volume while pitch is controlled by both the force of the air and the muscular tension applied to the membranes. Some birds can even produce two separate notes at the same instant because they can control both sides of the syrinx independently.

The two leading bird-song hypotheses of our time are that male birds sing to attract mates and to establish and protect territories. Those hypotheses are at least testable, have been tested, and look to be correct – as far as they go.

But even they don’t get at the root of the question. Bird song evolved along with birds. As far as we know, the dinosaurs from which birds evolved didn’t sing. (Maybe that’s the reason they died out! Nothing to do with volcanoes in Asia or a meteor strike in the Yucatán: They couldn’t sing! Of course, neither can I, so I am not fond of my new hypothesis about dinosaur extinction. If true, it doesn’t bode well for my continued survival nor that of my children, who can’t sing either.) The first dinosaur-birds probably didn’t sing and certainly did not have the highly developed language of many current bird species.

But at some point we must assume the male birds that croaked out rudimentary songs had a sexual advantage over their competitors who hadn’t figured out anything more than avian karaoke. Otherwise, they wouldn’t be singing today

Said differently, why weren’t the ordinary, simpler, and easier-to-learn bird calls enough?

For that matter, why did the males of so many species develop their brilliant colors? That too takes more evolutionary effort than dull and drab. Moreover, brilliantly colored birds are easier for those predators which have color vision to spot. The same is true for song. A robin singing away in pre-dawn light is easier for a predator to find than if the robin was emitting only an occasional high-pitched call. Why does the robin take the risk? Natural selection, after all, destroys without fear or favor. Why is a noisy robin more likely to pass along his genes than one sitting quietly hidden two feet away?

The possibility exists that beauty plays a role. Maybe the bird that sings most beautifully is the one most likely to breed in spite of the danger? For those of you with a scientific/materialistic frame of mind, nothing excludes such a possibility: Beauty may be adaptive. How else to explain the Elegant Trogan? For those readers of a more spiritual/religious framework, why would beauty not be a survival requirement? How else to explain the Elegant Trogan?

But before we can go further we have to deal with “The Mockingbird Problem.” We’ll be back next time to discuss mockingbirds and their songs.

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The photo of the fossil dromaeosaur  at the American Museum of Natural History in New York was taken by Dinoguy2.

Quick Thought for Your Day

Our chickens have new gates, in part because one of the Border Collies had discovered a way through the old ones – not, mind you -  to get at the chickens. No, this dog learned a way into their coop so she could eat their food. She’s been putting on a little weight lately.

The chickens talked about their new gates and reminded us of Mark Twain,

“Noise proves nothing.  Often a hen who has merely laid an egg cackles as if she has laid an asteroid.”

The Gulf of Mexico Disaster

Comment about this recent NOAA/NASA photograph would be superfluous.  (Click for a larger version.)

Birds of Peru

It’s not easy to write a book review of a birding field guide. One cannot write the wonderful zingers that other book reviewers sometimes get off:

“This is not a novel to be tossed aside lightly. It should be thrown with great force.” (Dorothy Parker)

“I did not know that fourteen publishers had turned down this book. If true, it’s the most encouraging thing I have heard about the publishing industry in years.” (A.J. Liebling)

“The poet accepts oblivion; his lessers seek survival.” (Murray Kempton)

“I never read a book before reviewing it – it prejudices a man so.” (Sydney Smith.)

“Humor can be dissected, as a frog can, but the thing dies in the process and the innards are discouraging. . .” (E.B. White)

But one cannot dodge the task  assigned. The Princeton University Press just sent us a review copy of its revised, updated Birds of Peru from its Princeton Field Guide series, so we can hardly decline to review it. That would be rude and birders are never rude.

Besides, the book covers all of Peru’s 1,817 confirmed species. That’s right, 1,817.  Hummingbirds consume forty pages all by themselves. We count 91 species of Tanagers alone. Where else could you expect to find the field markings and range map for the Rufous-Breasted Chat-Tyrant that lives on the ribs of the Andes? Or examine detailed, excellent illustrations of the thirty species of Antwrens that live in Peru. Or learn about the “professional” followers of the Army Ants that swarm on the floor of tropical forests. These birds follow the swarms and dine on the spiders and small vertebrates that flee the ants.

You may not have known that the Stygian Owl’s status in Peru is not clear. It may be rare or local or just “overlooked.” It’s probably easy to overlook birds in the vast Amazonian Basin. It’s full of trees after all. Twenty-nine major rivers drain the Andes in Peru; most end up in the Amazon.

Five authors and five principal illustrators fill the book with orderly information with a range map just to the left of each species and a right-hand page full of truly fine illustrations of each bird. If there is a bird in Peru that can’t be identified using this field guide and a pair of binoculars, I’d like to see it. The news release announcing the publication date (June 2, 2010) claims that this book is “the most complete and authoritative field guide to this diverse, neotropical landscape.” We believe it. If you’ve never looked at any of Princeton’s bird books, you’ll be surprised at the amount of detailed information they all contain.

It is the fashion in short book reviews these days to insert a paragraph toward the end complaining about something. We expect that is to prove that the reviewer actually read the thing. We have such a complaint: This book is 664 pages of print that is too small for eyes over forty years of age to read without reading glasses. I suppose Princeton claims that the print had to be small or the book would have weighed too much for a field guide. (It almost is too heavy as it is.) The authors admit to having jettisoned, “often with great reluctance” much additional information.

Rufous-Breasted Chat-Tyrant

Plus, 1,817 bird species do rather fill up a field guide.

And what a field guide it is. We’ve never been to Peru and haven’t got a trip planned and we’ve spent hours just thumbing through it. The Peruvian Tourist Authority ought to buy several thousand copies to distribute to tourist agencies. If you never wanted to see Peru, you will after spending some time inside the covers of this book. And you can go anytime. According to the book, most Peruvian species live there year-round.

We’re just sorry that it doesn’t lend itself to any book review zingers like Ambrose Bierce’s, “The covers of this book are too far apart.”

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The paperback version costs $39.50 and is worth every penny. We’ll be happy to get it for you.

Memorial Day 2010

Today the United States observes its Memorial Day, taking a moment to remember and honor all the Nation’s servicemen who died in our wars. Begun after our Civil War, it became official after World War I.

Wars are more than human tragedies of course. They are ecological disasters. Flora and fauna suffer as well. Here, from Wikipedia, is a photo of Chateau Wood during the third battle of Ypres, commonly known as the Battle of Passchendaele, which raged from June until November of 1917.

From the looks of the trees, bird song did not accompany those Australian soldiers on their walk. Birds withstand artillery barrages no better than humans or trees.

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The photographer was Frank Hurley and the photo is in the public domain.