4/97 Psychology of Music

Dr. W.S. Mayo

Bird Song Development

After the chilling winter is past the sound of singing birds is warmly welcomed. Bird song is enjoyed because it is a sign of spring’s arrival; but, its’ purpose is more significant. Birds vocally communicate for survival. Song communication is a complex process that not all birds possess and it is not present the moment birds are born. Developing song is a skill that combines a circuitous neural process with environmental influences. It has been observed that the way birds learn to sing correlates with how people learn through action. The bird’s process of learning will be examined for the sake of making an analogy to how humans learn. The points that will be discussed involve identification of the types of species that produce song, and most importantly, will investigate the song learning process.

The family that produces song birds is the oscine family. Almost half of the world’s varieties are oscines. It is the male of the species that dominates singing. They use songs to display that allows for dispute without physical attack. This manner of communication, or duetting, is formally called song-bout . The attached graph entitled Structure in the World illustrates this behavior. (This graph was taken from:http://cogsci.ucsd.edu/ ~cfry/ bird/dcog/world.gif) .

To elaborate further, an example will be given of three birds named A,B, and C. If bird A hears bird B singing on the border of its’ territory, then it will sing weakly. If bird A hears a strange bird singing on the border of A and B’s territory, A will sing strongly. If bird A hears bird B’s song on the border of A and bird C’s territory, then A will sing strongly as well. Birds will protect their own regions and give out warning signs to others. (This example is as cited from : http://www.bio.umass.edu/faculty/ biog/kroodsma.html).

As mentioned before, song is used in mating. In male brown-headed cowbirds (molothrus ater) it has been observed that they will learn to sing a certain type of song that evokes a "wing stroke" display from the female of the species (Nelson, 1994). Interestingly, this was not a by-product of a sound stimulus, but it’s a visual one, learned by reinforcement.

How do these birds learn the songs that become so functional in their daily lives? In the past this issue has been confused as to if birds memorize most songs they hear or if they innately know which ones to retain (Nelson, 1994). A number of experiments have strongly suggested that birds not only are instructed by outside input, but they also adopt songs as trademarks. They do both at diverse levels of maturation. It involves two basic stages: memorization stage and the sensorimotor stage. The first is a general time of absorbing auditory input while the latter stage is a time of practice.

When birds are first born they are not immediately susceptible to acquiring song information. They do not sing at all. Sensitivity to sounds within their environment begins around 10 days and can last up to approximately 50 days (Marler, 1981). During Brown 3 this time the birds retain auditory information. According to Fry, a student at the University of California at San Diego, birds possess a "crude template" or, "an innate selectivity for their own species’ song" (as cited in: http://cogsci.ucsd.edu~cfry/ bird/ dcog/dcog.html). Research has shown that to a large extent, birds can be biased toward the output of their own species. The following experiments will examine how birds have typically reacted to auditory stimuli in controlled environments.

In a study conducted in 1981 for the Field Research Center for Ecology and Ethology at Rockefeller University, by Marler and Peters, 16 male swamp sparrows were raised in captivity. They were taken from the nest between the ages of 2 to 10 days and placed in acoustic isolation so that they would be unable to hear their own species’ song. In place of the sounds in their natural habitat, the birds were trained with recordings that modeled a mix of song-bouts performed by their own species added with those of the song sparrow species. The recordings were played twice a day, morning and evening, for 40 days.

Subsequently, the birds were individually isolated. Occurring between 30 and 100 days, the birds started to make sounds. As shown on sound spectrography, the sounds were not exact imitations of the recordings though. Instead, the birds had begun to invent their own songs and improvise upon the recordings.

Next, after what appeared to be a time of absorption, the birds stopped singing. They didn’t sing again for at least another 100 days; however, by day 298, all birds resumed activity. Recordings of the birds showed that they had memorized and fully crystallized songs by 334 days. Each bird was found to have an entire repertoire of 3 Brown 4 songs. All 16 followed the same developmental sequence: memorization, rehearsal, and performance.

Marler and Peters wrote, "Evidently sparrows commit song material heard in their first 2 months to memory and then keep it in storage, without rehearsal, for some 8 months. Only in early childhood, a time of rapid testicular growth and waxing of androgen production, do they begin transforming portions of the memorized material into matching sound patterns" (1981). This is the standard progression for young oscines, but what happens to bird song after the birds mature?

A more recent study was conducted in 1994 by Nelson, Professor at Leiden University in The Netherlands, and again, by Marler, Professor at the University of California at Davis. Nelson and Marler wanted to find out if birds with a developed repertoire would be able to memorize new material. They isolated 10 white-crowned sparrows individually. Each subject in this cohort was taken from the nest between the ages of 3 to 10 days and raised to independence. For comparison, six were selected in 1990 and four were selected in 1991. Two of the older birds were of the nuttalli sub-species and the rest were of the oriantha sub-species. The older set of birds already had song repertoire from the preceding spring. The younger birds had no crystallized song. They were used as a control group. The control birds were exposed to recordings of various song patterns by both sub-species for the first year of their lives. All birds developed song by the same developmental process as in the former experiment. Individual songs were recorded and digitized onto a computer for storage and replay purposes.

The birds were then split into two groups of five. One group was renamed the control and the other was the experimental. To individual birds in the new the control group, selected recordings were played of uncrystallized song that each had previously formed. The experimental group was presented with songs that the birds would not be familiar with. They were dispensed as completely new songs. All recordings were played repetitiously at appointed times each day. The experimental birds were given more time to hear the repetitions. Results found that the control group formed similar songs based on the ones they heard while the experimental group sang crystallizations of songs they already formed. Essentially, once past a certain age, the birds were unable to acquire songs they had not been exposed to.

These results are explained as a consequence of age and sexual development. Birds can acquire new songs until they outgrow the memorization stage at the time of reaching full sexual maturity. This is why the younger control group was able to closely reproduce the songs form the recordings and why the older birds were not able to acquire songs by simply hearing new recordings. Prior to sexual maturity, birds are able to match the sounds in their environments through the memorization and sensorimotor processes of imitation and improvisation. After maturity, birds learn songs by way of reinforcement. They will selectively appropriate songs that serve a purpose. They will learn songs that will attract the female and that will help them defend their territory against neighboring rivals, as mentioned before. It was recorded that birds rehearse the songs they hear before they are fully crystallized. These recordings can be observed by looking at sound spectrography (see graph entitled A Bird Song, taken from http://cogsci.ucsd.edu~cfry/bird/intro.1.html). Sound spectrography maps out the sound waves produced by the birds, plotting sound pressure over time. The sound waves make up a series of waves or "syllables" separated by flat lines which represent moments of silence (http://cogsci.ucsd.edu…intro.1.html). On the graph entitled "A Bird Song," the sound wave is shown as having a lot of repetition. The first four syllables and the last three syllables are at the same intervals. If one were to see the first expressions of sparrow song, they would see a series of downward slashes representing wide pitch movement in the syllables. The innate sound is redundant, but it evolves into a multinote exposition. The syllables of evolving sound looks very irregular on a spectrograph. The syllables are often polarized in pitch and each pitch can vary in duration. There is no predictability during this time, with the exception that eventually, a permanent song will be disclosed when maturity is reached.

Up to this point only the aural aspects of bird development has been discussed. The only exception has been in regards to the hidden motivation behind which songs the bird chooses to learn. The neurological process of activating a bird’s auditory template goes through specific anatomy located in the brain. This learning pathway is illustrated on the graph entitled The Neurology of Birdsong Learning (as taken from: http://cogsci.ucsd.edu/~cfry/bird/brain.html).

Within the bird brain (namely, the sparrow) there is a set of nuclei called the hyperstriatum ventrale, or higher vocal center (HVC) according to Donald Kroodsma, Professor of Zoology at the University of Massachusetts (1982). The diagram shows it as being located toward the top-back of the bird head. From this group of nuclei, neural Brown 7 projections are sent to area X, on to the medial nucleus of the dorssalateral thalamus (DLM). It continues on to the lateral magnocelluar nucleus of the anterior neostriatum (LMAN) to finally stop in the robust nucleus of the archistriatum (RA) (as cited in http://cogsci.ucsd.edu…). This pathway moves throughout the anterior section of the brain. Conversely, the production pathway circulates toward the back of the brain. Marked on the graph by white arrows, the process begins also in the HVC. Neural projections descend to the RA, and down to the hypoglossal neurons (labeled as: nXIIts). Kroodsma also notes that it is the hypoglossal neurons that are a significant part of anatomy because they "innervate the syrinx," the bird equivalent of the human throat (1982). Thus, it is the nerves that help the syrinx to operate. The diagram entitled The Model Syrinx shows the passage of airflow (taken from: http://cogsci.ucsd.edu/~cfry/ bird/comp.4.html). The diagram to the right of the syrinx shows a magnified view of the sound mechanisms that are the means of producing sound. These mechanisms are called the tympanic membranes. Controlled by syringeal muscles, these membranes vibrate to produce sound and pitch.

As it has been explained from the experiments, it is most plausible that for those kinds of birds that must teach themselves to sing by imitating models, they learn first by memorizing song. Later, they lose this ability, only to gain more songs as their survival deems necessary.. Donald A. Hodges, editor of the Handbook of Music Psychology, calls the stages of development an "action-based" system (1996). It is the operation of birds adapting to their habitats that is similar to how humans learn basic functions.

Infants learn to walk, speak, do skills, and maintain proper cultural behavior by imitating the people around them. In the infant stage, a child will babble and coo until they reach the age where they are mentally capable of speaking. Parents often stand their children up on their feet long before they are equipped to walk. Children are placed in walkers and "jolly jumpers" where they can safely exercise physical skills. Likewise, child will learn proper manners and socialization by imitating the example of their parents and friends. Skill acquisition is marked by a constant balancing between imitation, practice, and performance. It is certainly true regarding musical skill.

From a personal standpoint, I attribute all of my musical ability to my heritage first, and to my training second. I am sure that it is no accident that I am musical. My grandparents and both of my parents were musical. Because of this circumstance, I was brought up around music. I learned to sing on pitch at an early age because my mother sang with me. I enjoyed singing because she reinforced me as a child. When I grew older, I was reinforced by my elders and peers. They enjoyed my singing as well and it inspired me to sing more. My culture strengthened my innate and selective desire to be musical.

Not everyone has received my sort of upbringing though. There are people who have spent their focus on learning to do other things well. If such a person has minimal concept of how to produce music, then they need exposure to what it is like to be musical through experience. Experiences need to be set up in a way that they can receive positive reinforcement while learning. Subsequently, they need to come to an understanding that music has a use for them in their lives. They need to be motivated enough that they will want to continue to have musical experiences at progressing levels. Just like the sparrow needs to sing in order to survive, a student needs a use for having musical ability to a certain motivational extent. Just like a bird acquires new songs later in life by reinforcement by the opposite sex, so a student needs reinforcement for the things they learn.

Bibliography

1) Fry, C. Bird Song Learning. http://cogsci.ucsd.edu/~cfry/bird/modeltour.html (Internet. Altavista search engine. April 23, 1997.).

2) Fry, C. The Distributed Cognition of Birdsong. Notes on Chris Fry’s presentation the Distributed Cognition Lab on April 19. 1995. http://cogsci.ucsd.edu/~cfry/bird/dcog/dcog.html (Internet. Infoseek search engine. April 23, 1997).

3) Hodges, D. (Ed.). (1996). Handbook of Music Psychology. San Antonio: IMR Press.

4)Kroodsma, D. Bird Song. Notes for Lecture on May 28. http://www.bio. umass.edu/faculty/biog/kroodsma.html (Internet. April 23, 1997).

5) Kroodsma, D., Miller, E., & Ouellet, H. (Eds.). (1982). Communication and Behavior An Interdisciplinary Series. Production, Perception, and Design Features of Sounds. Vol. 1. New York: Academic Press.

6) Marler, P., Peters, S. (1981). Sparrows Learn Adult Song and More From Memory. Science, 213, 780-782.

7) Nelson, D. & Marler, P. (1994). Selection-based Learning in Bird Song Development. Proceedings of the National Academy of Science, 91, 10498-10510.

Summary of Resources

1) Fry, C. Bird Song Learning. http://cogsci.ucsd.edu/~cfry/bird/modeltour.html (Internet. Altavista search engine. April 23, 1997.). This is a comprehensive research project given by Fry, a student at the University of California at San Diego. He is part of the Cognitive Science Department. On this homepage he gave graphs and summaries of all the aspects of his research. He showed neural maps of how the bird selects out which acoustical properties to retain in each song it memorizes. It has recordings of bird songs at various developmental stages. It is quite impressive and was the most valuable resource to me on the Net.

2) Fry, C. The Distributed Cognition of Birdsong. Notes on Chris Fry’s presentation in the Distributed Cognition Lab on April 19, 1995. http://cogsci.ucsd.edu/~cfry/bird dcog/dcog.html (Internet. Infoseek search engine. April 23, 1997.). This is another page put on the Net by Fry. This is only an explanation of bird song as it pertains to song-bout. It includes some information regarding neural anatomy, but it also contains a lot of illustrations.

3) Hodges, D. (Ed.). (1996). Handbook of Music Psychology. San Antonio: IMR Press. This is our class text. I used the small birdsong section located on page 208. It is a chapter that talks about how animals respond to pitch input. It relates the information to human development.

4) Kroodsma, D. Bird Song. Notes for Lecture on May 28. http://www.bio.umass.edu/ faculty/biog/kroodsma.html (Internet. April 23, 1997.). This is an outline of a lecture. In it is included some illustrations which I included in my paper. It also contains a bibliography of other sources.

5) Kroodsma, D., Miller, E., & Ouellet, H. (Eds.). (1982). Communication and Behavior an Interdisciplinary Series. Production, Perception, and Design Features of Sounds. Vol. 1. New York: Academic Press. This is an extensive two volumes of all you ever wanted to know about birds in regards to the biology, neurology, behavior, and scientific information about various types of birds. There are few pictures. The part I used was a description of the neural processes of bird song development.

6) Marler, P., & Peters, S. (1981). Sparrows Learn adult Song and More From Memory. Science, 213, 780-782. Summary of Resources Continued This was a journal article of an experiment done in 1981. I was afraid that it would be outdated, but compared to the other more recent sources I used, it still remains accurate. It is an experiment on the sensorimotor stage alone. It has spectrography of different bird songs on it. It was helpful to be able to compare these in a before-and-after sense as it correlated with the experiment.

7) Nelson, D. & Marler, P. (1994). Selection-based Learning in Bird Song Development. Proceedings of the National Academy of Science, 91, 10498-15010. This was another journal article of an experiment done in 1994. The researchers set out to prove their hypothesis about how birds are unable to learn song after maturity. They included extensive spectrographic analysis o their subjects and an extensive conclusion.