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Just Duet

Biologists puzzle over birds' ensemble vocalizations

Susan Milius

As the morning mists rose on the slopes of Ecuador's Pasochoa volcano, the burbling of plain-tailed wrens came through the bamboo thickets. Two researchers started their standard procedure of catching wrens, banding them, and letting them go. Soon, however, they were startled when a small cluster of wrens settled into a bush and began singing together. It turned out to be "one of the most complex singing performances yet described in a nonhuman animal," says Nigel Mann.

a6940_1740.jpg

CHORUS LINES. The song of the plain-tailed wren of Ecuador sounds like one continuous bubbling tone. However, it comes from two birds and often more. In the jagged sonogram trace (bottom), males sing two kinds of sections (under blue bars) and females fill in gaps with two kinds of phrases (under red bars). Double bars represent two same-sex singers.
Mann/Biology Letters

Mann, of the State University of New York at Oneonta, and a colleague had gone to Pasochoa in the summer of 2002 as part of a team that was surveying of the 28-or-so species of the bird genus Thryothorus. That genus is famous for musical duets, in which a male and a female alternate phrases, sometimes so rapidly that it sounds like one song. Ecuador's plain-tailed wrens (Thryothorus euophrys), relatives of North America's Carolina wren, make a rhythmic, bubbling song together.

Most other wrens in this genus pair off and fiercely defend a territory. "If [four wrens] actually got within a few feet of each other, they'd be fighting," says Mann. That's why he and Kimberly A. Dingess of Indiana University at Bloomington were so surprised to find several plain-tailed wrens sharing a bush. "It took a few hours of wandering around for us to realize we had a group-living species," Mann says.

This social oddity has musical consequences. Often, three or more birds sing—males, then females, then males, and so on—to produce what sounds like a single melody.

"It's quite difficult to work out what's Charlie's contribution, what's Mary's," Mann says.

Yet the scientists did work out the score. At rare moments in the several weeks of observation, Mann or Dingess picked up clues to which bird was singing when one singer perched closer to the microphone than the rest of the chorus did.

From these hard-won moments, the researchers realized that songs typically repeat four phrases: ABCDABCD.... Only males sing the As and Cs, and only females sing Bs and Ds. Each singer knows 25-to-30 variations on each of its two possible parts, and for each variation of A, a particular variation of B usually follows, as do particular Ds after Cs.

When more than two birds strike up a tune, they double up on the parts so precisely that if one bird stops singing, the tune keeps going. The males sing the same variation of A with precise timing, followed by the females chorusing the same version of B, then back to the males for the same C, and so on. The parts shift back and forth at least twice a second. For samples of sound files of duets, click here.

It's the first four-part, synchronized chorus with alternating parts recorded outside human music, Mann, Dingess, and Peter J.B. Slater of the University of St. Andrews in Scotland report in the March 22 Biology Letters. And when one considers the split-second alternation, the birds' singing surpasses human vocal virtuosity.

That's the latest, most extreme example of duetting birds, a phenomenon that has fascinated birders for decades and inspired its own chorus of theorizing about what might drive such displays. Warning off rivals? Foiling flirtations? Checking musical passwords? In the past few years, field biologists have applied modern ideas about evolution to begin new tests of why duetters do it.

Singing double

Honks, squeaks, and melodic syllables can all be scored into avian duets. In at least 222 bird species worldwide, or about 3 percent of those known, two or more individuals routinely coordinate their vocalizations.

Duetting shows up in a range of bird families and takes many forms, says Michelle Hall of the Australian National University in Canberra. Although members of a mated pair typically alternate as they sing their parts, duos within some species sing in unison. In a few cases, two males vocalize together, or several birds form an ensemble, as among the plain-tailed wrens.

An ornithological sorrow of life in northern temperate zones is the scarcity of duetting birds. The few nontropical birds that perform together generally do simple numbers.

Ornithologists have described male and female Canada geese alternating honks. And Lauryn Benedict of the University of California, Berkeley is studying a duet of California towhees where male and females produce simultaneous, near-identical, squeal-like vocalizations that are used only in duets and never alone.

Most birds that duet—and the most interesting vocal interactions—come from somewhere other than northern temperate zones.

Among magpie-larks, which Hall studied during the 1990s, males and females sing solo as well as together. Common in Australian suburbs, the long-legged, black-and-white birds "can sound a little raucous," says Hall. Either sex can initiate a duet, typically starting to repeat one of nine musical motifs, such as "peewee," with a gap of a third to a half second between repetitions. On occasion, the mate inserts another motif in the gaps to make, for example, a "peewee o-wit peewee o-wit peewee" duet.

Male eastern whipbirds in Australia start a duet with a whistle and a sound like that of a cracking whip, and females chime in with several notes. Up and down Australia's east coast, males sounded remarkably similar, but females had regional variations, report Amy Rogers of the University of Melbourne and Daniel Mennill of the University of Windsor in Ontario in the January Journal of Avian Biology.

In one of the rare male-male duets, two long-tailed manakins advertise the location of a courtship perch by simultaneously singing "Toledo."

Male-manakin duos with the tightest coordination get the most visitors, report Jill Trainer of the University of Northern Iowa and her colleagues. However, only the dominant male of a singing pair does any mating. The second manakin can spend up to 10 years with no apparent reward but his increasing skill in singing along.

Why, oh why?

Over several decades, scientists have offered at least a dozen explanations for the purpose of avian duets. The theories have focused on the forest, the pair, or conflicts of interest between individual birds.

The abundance of duetting in the tropics inspired some of the early explanations. Scientists in the 1970s noted that dense tropical vegetation would make sound especially important for mates identifying each other or keeping in contact. Recently, theorists have suggested that tropical birds duet to stay in sync reproductively, despite limited seasonal cues such as changes in day length.

Other scientists have stressed the partnership. For example, in the 1980s, the "coyness hypothesis" proposed that birds that consummated their pairing only after the arduous job of learning to duet would have a stronger bond that would discourage extra-pair adventuring.

Yet other theorists have suggested that duetting enables a bird to judge its mate's commitment to the partnership. Discouraging interlopers has been a popular theme, both in duetting to defend a territory and duetting to drive away a potential mate stealer.

Several current duet researchers trace their interest in the field to 1996 papers by Rachel Levin, now of Pomona College in Claremont, Calif. Her work challenged the idea that achieving coordinated singing is a difficult task.

Levin studied Panama's bay wrens, which duet with rapid-fire, his-her alternation. When she kidnapped the mates of 10 bay wrens, the left-behind bird found a new mate and managed immediately to duet almost as well with the new partner as it had with the old.

Too often, these earlier theories treated a duet as a single, cooperative behavior performed for mutual advantage, Levin suggested. Because evolutionary forces act on individuals, Levin urged her colleagues to scrutinize the interests of individuals instead of happy pairs.

Levin's work "reignited the excitement about duets," says Mennill, who was inspired to take up the study of duetting in another tropical wren.

She's/he's mine

The current generation of duetting studies often compares his-and-her agendas. One possible agenda is the male's clear interest in fathering the female's chicks. He may be chiming in to the female's song as a musical claim to paternity. If so, Hall says, then a male should duet more when his partner is fertile than when she's not.

That idea didn't hold up in magpie-larks. Hall found that a female tends to sing less when fertile and that a male is less likely to join in when his singing partner is fertile than when she's not.

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TROPICAL TUNES. Males and females of many tropical Thryothorus wren species, such as the buff-breasted wren, trade parts back and forth so fast that they sound like one song. Sonogram traces 3.5 seconds of a wren duet, with the male's part in purple.
Gill

Buff-breasted wrens (Thryothorus leucotis) in Panama do something similar, says Sharon A. Gill, now at Princeton University. Males go "wop," and at times, females smoothly interpose "weooh."

Gill calculated females' fertile periods by keeping track of when they laid eggs. The mates started duets less frequently during these times than when the females weren't fertile, Gill reported in the April 2005 Behavioral Ecology and Sociobiology.

Males didn't seem that concerned about paternity in general, Gill says. She didn't find them sticking extra close to mates during fertile times. Nevertheless, only one of the 31 broods that she analyzed showed evidence of mixed parentage.

Even if duetting doesn't guard paternity, either partner might have an agenda "to defend their partnership," as Gill puts it. For example, consider the warbling antbirds in the Amazon (Hypocnemis cantator). Males sing solos, and, at times, females add girls-only song elements, report Nathalie Seddon and Joseph Tobias, both of the University of Oxford in England.

When the researchers played songs recorded from other warbling antbirds, both males and females were more likely to approach the speaker and to sing in response to same-sex solos than to male-female duets. When antbird couples hear recorded solos of a female, the resident male usually begins to sing. But then the resident female typically jumps in to duet sooner and more often than she does after recorded duets or male solos. That female is duetting to discourage same-sex interlopers, the researchers suggest in the January/February Behavioral Ecology.

African birds called tropical boubous (Laniarius aethiopicus) also show signs of mate guarding, but with a twist, Ulmar Grafe and Johannes Bitz of the University of Würzburg in Germany reported in 2004. When they played recorded male solos to pairs of birds, the female joined in to sing along. Then, in half of the six pairs studied, the female's mate started overlapping the notes in the recorded male solo. Grafe and Bitz interpreted this as a male jamming the signal from a too-enticing male intruder.

My land

Territory, as well as mates, might be worth duetting for. As many of the tropical duetters do, rufous-and-white wrens (Thryothorus rufalbus) defend their turf year-round. Their duets are "fluty, haunting-sounding," says Mennill, in contrast to the more-staccato bursts of other tropical wrens. In 70 percent of the rufous-and-white wrens' duets, the females join a male song, rather than the male picking up on a female's vocalization, Mennill reported in the January 2005 Auk.

The researcher moved around a pair of speakers, one broadcasting a male part in a duet and the other featuring the female, in an action mimicking that of a pair of wrens trespassing on various territories. The rightful territory owners approached the speakers with extra bursts of their own solo and duet songs. They wagged their tails and chattered harshly at the speakers, as they do when chasing off real invaders, Mennill reports in the January Animal Behaviour.

Other studies in different species have pointed out that duetting birds often sing loudly from easy-to-see perches, just as solo territorial songsters do. Soloists and duetters both match bits of their songs with those of potential intruders, a one-upmanship contest (SN: 12/18&25/04, p. 397; Available to subscribers at http://www.sciencenews.org/articles/20041218/bob10.asp).

Grafe and Bitz have even proposed that boubous sing a particular kind of duet to advertise to the neighborhood that they've trounced a rival. The scientists have broadcast songs to simulate an invading pair of boubous and then compared the duets of resident birds that fled from the invasion with duets of birds that held their ground. After the confrontation, the steadfast pairs used a particular configuration of male-and-female notes in a duet that fleeing birds didn't use, the researchers reported in 2004.

The fury of territory defense led two researchers in 2004 to propose another function of duetting: distinguishing a fellow defender from an enemy. Black-bellied wrens (Thryothorus fasciatoventris) fuss and sing when researchers broadcast songs to mimic intruders, says David Logue of the University of Lethbridge in Alberta. He's researching what he calls duet codes, rules saying that a male's musical motif X goes with a female's motif Y. Females "always blast out the right answer," says Logue.

He and David Gammon of St. Edward's University in Austin, Texas, suggested in 2004 that duetting offers a way for black-bellied wren females to make sure that their mates don't attack them by mistake. The dense forests where these birds live distort sounds such as the "here I am" calls that other species use, says Logue. The wrens need an especially strong password system to tell friend from foe, he says.

Hall recounts anecdotes of attacks on intruders by cooperating birds. Purple-crowned fairy wrens, for example, spend much of their time near each other. "If one hops half-a-meter away, the other hops too," she says. And when they hear recorded songs in stereo, they both fly to chasten one speaker and then move together to the second. Hall says that she hopes someone will explore how widespread such defensive coordination might be among duetters.

All the ideas about the function of duets need more testing, she adds.

As bird duets start to make sense, maybe they'll shed light on other duetting species. Birds duet. Bugs duet. Even some primates do it.


All Together Now . . .

Employing terms and phrases such as "Toledo," "wop," "weooh," and "peewee o-wit peewee o-wit peewee" bird duet researchers can be quite creative in describing the sound recordings used in their work. Since there is no substitute for the original, however, we thought we'd supply a sampling of the actual sound files, along with tips from the scientists about what to listen for. For ease of reference, we have provided a link here, which will open the main article, "Just Duet," in a separate window.

 

From Nigel Mann:

Four-part chorus in plain-tailed wrens (Thryothorus euophrys).

 

a6940_340.jpg


 

p-t fig, 2nd.wav - This is a wren chorus of the type shown in the sonogram at right. Males sing the first and third elements (under blue bars) in each segment, and females interpose the second and fourth elements (under red bars). Double bars mean two birds are singing in unison (210 KB WAV file).

p-t long song.wav - This is a longer recording of the same species (1 MB WAV file).

 

From Lauryn Benedict:

Male-female duet in the California towhee, a rare temperate zone example of this behavior.

 

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Photo by Neil Losin

 

CALT song (161) 4-14-05.wav - This is an example of a typical male solo song (324 KB WAV file).

CALT duet (27&42) 6-28-04.wav - This duet of a male and female incorporates elements which males rarely sing alone. Females never sing other song types at all (453 WAV file).

 

From Daniel Mennill and Amy Rogers:

Eastern whipbird (Psophodes olivaceus) males start a duet with a whistle and a sound like a cracking whip.

The researchers include sonograms and sound files showing the regional variation found in female contributions to duets on their Web site at: http://web2.uwindsor.ca/courses/biology/dmennill/EAWH.html.

 

From Daniel Mennill:

Long-tailed manakins represent a rare example of a male-male duet.

Daniel Mennill's Web site includes a page with the "toledo" duet by two courting males, as well as other phrases used in the courting display at: http://web2.uwindsor.ca/courses/biology/
dmennill/CostaRica/LTMA/CRLTMA.html
.

 

From Sharon Gill:

Buff-breasted wren (Thryothorus leucotis) males and females trade parts back and forth within seconds.

 

a6940_5975.jpg


Photo by E.D. Alfson

 

Male-initiated duet.aif - An example of a duet initiated by the male (338 KB AIF file).

Female-initiated duet.aif - A duet started by the female of a mated pair (515 KB AIF file).

 

From Daniel Mennill:

Rufous-and-white wrens (Thryothorus rufalbus) defend their territory year-round.

A variety of solos and duets, which he describes as "fluty, [and] haunting-sounding" can be found on Dan Mennill's Web site at: http://web2.uwindsor.ca/courses/biology/
dmennill/CostaRica/RWWR/CRRWWR.html
.

 

From David Logue:

An example of a possible password code employed by black-bellied wrens (Thryothorus fasciatoventris).

To understand the duet code, Logue says, "Listen to the duet first, then the male and female songs that make it up, then the duet again. You can hear how in the duet, the female is responding to the male changing song type (1-2-1) by changing the song types she's using as responses (also 1-2-1)."

Duet.wav – The full duet (438 KB WAV file).

Male song 1.wav – Male song type 1 (87 KB WAV file).

Female song 1.wav – Female song type 1 (84 KB WAV file).

Male song 2.wav – Male song type 2 (82 KB WAV file).

Female song 2.wav – Female song type 2 (72 KB WAV file).

Fuente:

http://www.sciencenews.org/articles/20060128/bob9.asp

From Science NewsVol. 169, No. 4, Jan. 28, 2006, p. 58.

 

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Beyond Falsetto: Do mice sing at ultrasonic frequencies?

Ben Harder

Male mice may serenade prospective mates at pitches about two octaves higher than the shrillest sounds audible to people.

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SCIENTIFIC IDOL. Mice string "chirplike" ultrasonic noises (shown graphically in yellow) into song, according to a new report.
Holy and Guo

This "mouse song" is comparable in complexity to the sequences of tones that songbirds and some whales make, say Timothy E. Holy and Zhongsheng Guo of Washington University in St. Louis.

Other researchers remain guarded about labeling mouse vocalizations as song. Nevertheless, says neurophysiologist Xiaoqin Wang of Johns Hopkins University School of Medicine in Baltimore, the discovery that mice emit richly patterned ultrasonic noises could have important implications for the study of communication.

Scientists have known that mice produce ultrasound. When pups become isolated from their mothers, for example, they utter high-pitched cries that launch a maternal search-and-rescue operation. Adult males also vocalize when they detect female odors.

To investigate whether the adults make distinct syllables expressed in specific sequences, Holy and Guo recorded vocalizations by 45 male mice. The researchers placed the mice, one at a time, in a microphone-equipped chamber and inserted a urine-soaked cotton swab through a hole in one wall.

The investigators manipulated the resulting recordings to make ultrasonic noises audible to people (to listen to some samples, click here). The team used computer software to analyze the sounds.

Holy and Guo distinguished distinct syllable types according to, for example, how rapidly the sounds rose or fell in pitch. The animals emitted bursts of song containing about 10 syllables per second, the researchers report in the December PLoS Biology.

The mice repeated certain phrase sequences, creating acoustic motifs that meet established definitions of animal song, Holy and Guo conclude. Almost all the male mice in the study produced song, Holy says.

Neurobiologist Richard D. Mooney of Duke University Medical Center in Durham, N.C., says that the new "careful characterization" of mouse sounds provides a foundation for research that "could ultimately inform our understanding of speech."

Mice could become useful models for studying mammalian communication because, unlike monkeys, they can be genetically manipulated with ease, says Wang, who studies monkey communication.

Wang acknowledges that male mice produce strings of vocalizations that appear to have intrinsic structure. "But the fact that [vocalizations] are not random doesn't necessarily mean that they're songs," he cautions.

"I'm a little bit hesitant calling it song," agrees Robert C. Liu of Emory University in Atlanta, who has studied mouse vocalizations. Learning is "a crucial element of song in the classic sense."

While it's not clear that mice learn to sing, Holy suspects that they do. He notes that individual males display their own characteristic singing patterns. These could reflect variations in learning.

Other key questions include why male mice make the noises and how females respond, says Mooney.

Holy says, "My guess is that it's for the purposes of courtship."

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Holy and Guo

Fuente:

 http://www.sciencenews.org/articles/20051105/fob5.asp

References:

Holy, T.E., and Z. Guo. 2005. Ultrasonic songs of male mice. PLoS Biology 3(December):e386. Available at http://dx.doi.org/10.1371/journal.pbio.0030386.

To listen to some audio recordings of mouse "songs", go to www.sciencenews.org/articles/20051105/mousesongs.asp.

Monkeys May Tune In to Basic Melodies

Bruce Bower

Some tunes stick in one's memory, sometimes with remarkable persistence. Think of "Happy Birthday," "Old MacDonald," and "Row, Row, Row Your Boat." In laboratory experiments, even infants exhibit a keen memory for such songs.


 

 A dozen of these childhood classics prove as memorable to rhesus monkeys as they do to people, a new study finds. This represents the first well-controlled demonstration that any nonhuman animal perceives simple melodies, say psychologist Anthony A. Wright of the University of Texas Medical School at Houston and his colleagues. Their report appears in the September Journal of Experimental Psychology: General.

"The perception of melodies depends on the structure of our nervous systems, not just on childhood and cultural experiences," Wright contends. "It's anybody's guess why this ability evolved in monkeys as well as humans."

Wright's group studied octave generalization, a critical facet of melody perception. In Western musical scales, moving from one eight-note octave to the next highest octave represents a doubling of acoustic frequencies. If a melody's other acoustic properties, such as its pitch patterns and its key, stay the same, people easily recognize the tune when it shifts by one or more octaves.

Two earlier studies, one in 1943 with rats and one in 1988 with dolphins, also yielded evidence of octave generalization. However, those efforts lacked definitive experimental controls, Wright holds. Several other tests, including some with monkeys and songbirds, found no evidence for octave generalization.

The new study focused on a pair of adult rhesus monkeys that learned to report whether one sound matched another heard after a 1-second delay. Sounds included a boat whistle, owl hoots, and sonar pings. If the sounds were the same, a touch to a loudspeaker on the right yielded a food pellet; if the sounds differed, a touch to a speaker on the left earned the prize.

Using this approach, both monkeys accurately identified repeats of any of 12 childhood songs—including those cited above—even when the melody shifted by one or two octaves. The monkeys succeeded whether the tunes sounded as if they'd been played on a piano, guitar, or other instruments.

The animals also displayed octave generalization for new melodies, created according to a mathematical formula for tonal, well-structured tunes. Tonality refers to the relationship of a melody's tones to a central tone, or key, that gives the passage a musical or songlike nature.

As previously reported for people's musical skills, the animals' ability to identify childhood songs plummeted when they heard tunes that shifted by either one-half octave or 1 1/2 octaves. In these trials, the monkeys touched the speakers randomly. Similar problems arose when they heard octave shifts of single notes, random sets of notes, or atonal sequences, in which there's no key.

"Wright's group makes a good case that these monkeys perceive whole tunes, not just isolated notes," remarks psychologist Sandra Trehub of the University of Toronto. Trehub, who studies infants' musical perception, theorizes that many mammals are sensitive to basic musical patterns.

Scientists have yet to reach a consensus on how to quantify the tonality of a sequence of musical notes, a concept that's crucial in the new study, comments psychologist Diana Deutsch of the University of California, San Diego. Although octave generalization probably occurs in nonhuman animals, Deutsch says the new experiments don't establish that monkeys perceive music.

References:

Wright, A.A., et al. 2000. Music perception and octave generalization in rhesus monkeys. Journal of Experimental Psychology: General 129(September):291-307. Abstract.

Fuente:

http://www.sciencenews.org/articles/20000916/fob1.asp

 

Canary Songs

Canary Songs

Ivars Peterson

All it takes to sing like a canary is good breath and muscle control. Simply by manipulating air pressure and muscle tension in its vocal organ, or syrinx, a canary can generate an amazingly varied repertoire of trills, warbles, and other melodic syllables.

This insight comes from a novel mathematical model of sound production in a songbird's vocal organ.

In mathematical terms, "much of the complexity of the song of the canary (Serinus canaria) can be produced from simple time variations in forcing functions," Tim Gardner of Rockefeller University and his collaborators declared in the Nov. 12 Physical Review Letters.

Recent experiments suggest that a canary's syrinx generates sounds via vibrations of its labia—flaps of tissue that sit where a songbird's two bronchial passages meet its windpipe. The labia behave somewhat like a clarinet's reed, oscillating air that rushes past them. Muscles modify the stiffness of the labia and the width of the gap between the folds.

To develop their model of the syrinx, Gardner and his coworkers assumed that the labial folds act like a spring, moving back and forth to alter the size of the air passage. They also assumed that a canary uses just two mechanisms to control its vocalizations: changing the pressure of air from the lungs and modifying the stiffness of the folds. The researchers expressed their model in terms of a differential equation involving damped harmonic oscillators.

Computer simulations showed that by simply varying the air pressure and stiffness, it's possible to recreate much of a canary's rich repertoire. Indeed, some sequences of notes result from little more than a slowly changing phase relationship between oscillations governing air pressure and those controlling labial stiffness. Such cyclic behavior is characteristic of a wide variety of coupled oscillators.

"The starts, stops, and pauses between syllables, as well as variation in pitch and timbre, are inherent in the mechanics and can often be expressed through smooth and simple variations in the frequency and relative phase of two driving parameters," the researchers concluded.

In other words, it may not require a lot of brain power on the part of a canary to sing its heart out and attract a mate.

Fuente:

http://www.sciencenews.org/articles/20011124/mathtrek.asp

Listen to Bird Songs/ escucha el Canto de las Aves

Bird Calls

 

The Macaulay Library at Cornell University has the largest collection of animal sounds in the world. More than 67 percent of the world's birds are represented in the center's 160,000 recordings, along with sounds made by insects, fish, frogs, and mammals. The Library also archives and preserves a sampling of the behaviors of different animal species using digital video and audio. Download the songs of various backyard birds, from chickadees to goldfinches, at the following Web page.

Go to: http://www.birds.cornell.edu/MacaulayLibrary/search/freesounds.html

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Big-Eyed Birds Sing Early Songs: Dawn chorus explained

Big-Eyed Birds Sing Early Songs: Dawn chorus explained

John Pickrell

As dawn breaks on a misty Welsh morning, the earliest birds to break into song are likely to include European robins, followed by blackbirds and song thrushes and then a plethora of other species as sunlight crowns the horizon. The last to join the chorus, such as chaffinches and blue tits, may not chime in until 100 minutes after the first crooners began.

a1603_1747.jpg

SUNRISE SERENADE. Big-eyed birds such as the European robin (above) start singing much earlier than neighbors like the house sparrow (below), whose eye is 80 percent as large.
RSPB Images

This pattern is repeated worldwide, and ornithologists have often pondered what determines when a particular species begins its morning singing. Now, scientists say that they've found the explanation: The larger a bird's eyes, the earlier it starts to sing.

The staggering of avian choruses was first documented 70 years ago but has remained unexplained. Now, researchers have revisited an idea first proposed in the 1960s but never tested. It's that visual acuity—determined by eye size—governs when birds start to sing.

Robert J. Thomas at the University of Bristol in England and his coworkers recorded the time and intensity of light at the moment when each species broke into song at seven European woodland sites. The researchers then temporarily captured individuals from 57 of these species and used calipers to take rough measurements of eye-surface diameter.

a1603_2602.jpg


In the April 22 Proceedings of the Royal Society B, the researchers report a strong relationship between the light intensity at which birds start to sing and eye size. "Birds with big eyes do start to sing earlier," says Thomas. The relationship remained even after the scientists used statistics to discount other factors such as body size.

"Even though the result is expected, it's an excellent example of the way in which visual capabilities affect communications behavior," says Sandra Vehrencamp of Cornell University.

Birds singing at dawn and dusk attract mates and defend their territories. However, this musical interlude can be hazardous since it can draw the attention of predators, such as tawny owls, to a bird's location. The singing also makes it difficult for a bird to hear danger coming, says Thomas. It therefore makes sense, he adds, that singing not begin until the bird can be on the lookout for trouble.

References:

Thomas, R.J., et al. 2002. Eye size in birds and the timing of song at dawn. Proceedings of the Royal Society of London B 269(April 22):831-837. Abstract available at http://dx.doi.org/10.1098/rspb.2001.1941.

Sources:

Robert J. Thomas
Centre for Behavioral Biology
School of Biological Sciences
University of Bristol
Bristol BS8 1UG
United Kingdom

Sandra Vehrencamp
Department of Neurobiology and Behavior
Cornell University
Ithaca, NY 14853

Fuente:

http://www.sciencenews.org/articles/20020420/fob7.as

om Science NewsVol. 161, No. 16, April 20, 2002, p. 245.

Listen to Whale Songs/ Escucha el Canto de las Ballenas


 

Listen to the songs of whales and the sounds of the ocean near Maui, Hawaii. The Whalesong Project is the effort of a group of volunteers to bring attention to the beauty of oceans and the wonder of whales and dolphins.

Go to: http://www.whalesong.net/

Proyecto Biomúsica

Proyecto Biomúsica

Proyecto Biomúsica.

 

Desde que el hombre existe ha habido música. Pero también los animales, los átomos y las estrellas hacen música.

Karlheinz Stockhausen

El proyecto Biomúsica tiene cómo misión explorar y difundir el fenómeno de la música desde un punto de vista evolutivo y comparativo de la diversidad de formas en que los animales y las culturas humanas se comunican utilizando los sonidos musicales. A partir de esto se espera aportar a la comprensión sobre las raíces, funciones y el proceso evolutivo de la música humana y sobre el potencial de la música como medio para recrear los vínculos culturales, emocionales y espirituales que el ser humano establece consigo mismo, entre sus pares, con la naturaleza y los diversos seres vivos que en ella habitan. Finalmente el proyecto busca sensibilizar, dar a conocer y acercar al público en general a los sonidos de la naturaleza y su relación con la música humana, aportando con ello a la valoración, rescate, identificación y conservación de la Biodiversidad Acústica del mundo natural y cultural del ser humano.


Objetivos:

  1. Explorar, expandir y difundir el vasto y variado mundo de interrelaciones acústicas adentro y entre distintas especies: La música de la naturaleza.

  1. Explorar los patrones que relacionan los sonidos musicales producidos por diversas especies animales y la música humana: La naturaleza de la música.

  2. Revelar nuevos significados y modos de experimentar y aprender de nuestro medio ambiente y de los animales a través del mundo del sonido y de la música.

  1. Explorar como la música podría ser un canal de comunicación entre los seres humanos y otras especies de animales.

  1. Explorar los diversos roles funcionales y los usos de la música en todas las culturas humanas, especialmente los que han surgido en contextos rituales de representación o comunicación con el mundo natural.

  1. Convocar, reunir y empoderar a músicos, artistas y público en general, para recrear la relación del ser humano con la naturaleza y sus habitantes a través de la música y la danza.

  1. Aplicar estos hallazgos de modo tal de explorar el uso de los sonidos naturales y la música como herramienta terapéutica en diversos ámbitos con el objetivo de promover y reestablecer la salud física y mental en el ser humano y en otros seres vivos.

  1. Sensibilizar, educar y acercar al público en general a los sonidos de la naturaleza.

  1. Crear y producir obras artísticas basadas en los sonidos de la naturaleza.

  1. Rescatar, catalogar, conservar y difundir la biodiversidad acústica del mundo natural.

  1. Rescatar, catalogar, conservar y difundir la diversidad musical de las culturas humanas.


La Biomusicología:

La Biomúsica significa explorar la Naturaleza de la música y la música de la Naturaleza.

PHD Patricia Gray.

La Biomusicología es una nueva interdisciplina que deriva principalmente de la etología (estudio del comportamiento animal) y la musicología, la cual reúne tanto a científicos cómo a músicos que, a partir del estudio de los sonidos musicales en todas las especies animales, pretenden profundizar en la definición de lo que es la música y cómo es que esta evolucionó y continúa evolucionando.

Dentro de estas áreas del conocimiento la biomusicología se forma en relación a la pregunta sobre el origen, causas, funciones y posibles caminos evolutivos de la música, incluyendo en esto un rico camino de teoría y observación otorgado por la biología conductual, la psicología y la antropología en áreas como la comunicación, las vocalizaciones y la expresión emotiva en los seres humanos y en el resto de las especies del reino animal. De esta manera se intenta demostrar los parentescos musicales con otras especies focalizándose en los principios musicales que las investigaciones han revelado que son utilizadas y compartidas por nuestros parientes primates más cercanos (gibones, bonobos, ballenas, aves, elefantes entre otras) y todas las culturas humanas (tanto del pasado cómo del presente).

Las áreas principales de la biomusicología son:

  1. La Musicología Evolutiva: Los orígenes evolutivos de la música a través de una metodología comparativa de la comunicación vocal en animales y un punto de vista psicoevolutivo del surgimiento de la música en los homínidos.

  1. Neuromusicologia. La naturaleza y la evolución de los mecanismos neurales y cognitivos implicados en la producción y percepción musical, así como también al desarrollo ontogenético de las capacidades musicales desde el estadio fetal hasta la vejez.

  1. Musicología Comparada: Los diversos roles funcionales y los usos de la música en todas las culturas humanas, incluidos los contextos y los contenidos de los rituales musicales, las ventajas y costos de la producción musical y la comparación de los diversos sistemas, formas y estilos interpretativos a través del mundo entero.

  1. La comunicación Interespecífica, es decir, las múltiples formas en que se establecen comunicaciones entre especies distintas, y como la música podría ser un canal de comunicación entre los seres humanos y otras especies en las cuales la comunicación acústica cumpla un rol preponderante.

  1. Musicoterapia: El uso de los sonidos y la música como herramienta terapéutica en diversos ámbitos con el objetivo de promover y reestablecer la salud física y mental en el ser humano y en otros seres vivos.

De esta manera los sonidos musicales en el reino animal son observados como un ingrediente básico del proceso no verbal de la comunicación, revelando nuevos significados y modos de experimentar y aprender de nuestro medio ambiente y especialmente de los animales, para de esta manera expandir nuestra definición de la música, ampliando nuestra visión sobre el rol que cumple en la biodiversidad y el desarrollo humano, contribuyendo al entendimiento del proceso fundamental de la música y cómo este trabaja a través nuestro y de la biosfera. La música podrá imitar a la naturaleza, no sonando sólo como ella si no trabajando (operando) cómo ella, siendo parte de un arte que surge de la naturaleza debido a su propia manera de operar, por esto se busca entender la música de la naturaleza y por lo tanto develar su rol evolutivo en este gran contexto.

José Fco Zamorano A.


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