Bird song
Aims
•Be able to describe the three neuronal pathways involved in birdsong

•Be able to explain and evaluate how the learning of birdsong is investigated

•Be able to explain the findings of Thorpe’s early experiments

•Be able to explain the stages of song development and appreciate how it differs

•Be able to explain Marler’s observation on how birds crystallize their songs and link this to neuronal changes

•Be able to explain Konishi’s key experiments on auditory feedback

•Explain and evaluate the idea of templates, and the differences between them.

•Use examples of electophysiological experiments support as support for templates

What is bird song

•Spontaneous whistles, chirps, complex songs

•Communication – defending territory, attracting a mate, finding conspecifics, identifying individuals and their background.

•4000 of the 9000 species of birds can sing. These are in the order Passeriformes (passerines) or perching birds.

•Song repertoires can range from 1 song (white-crowned sparrow) to several thousand (brown thrasher)

•Bird song is both species specific, and modified to the individual (dialects).

•Mostly, only male birds sing.

Why is it important to understand how birds learn songs

There are similar parts of the brain used to learn language and birdsong. Both have a sensitive critical period where observed behaviour is learnt. There are similarities in stages of development and experience is vital for both. Auditory feedback is key for both whilst learning how to make sounds and they are reinforced by social interaction. On the other hand bird songs are not as complex as language

Birds are a good research model as they are accessible , easily reared amd songs can be recorded, manipulated and analysed.

•Be able to describe the three neuronal pathways involved in birdsong

1.Auditorypathwaytohearingbirdsong.

Auditorynoise

2.Anteriorforebraipathway Neurons within the Higher vocal center and send projections to DLM to LMAN , RA

3.Song motor/production pathway (posterior vocal pathway)

HVC-RA-respiratory control and nXIIts

Syrinx and sound production
Muscular tension modulates the vibrations and sound made.
1.Air comes from air sacs not lungs

2.Body wall muscle expels air from air sacs

3.Air movement causes tympaniform membranes to vibrate creating sound waves

4.Internal and external syringeal muscles alter tension of tympaniform membrane altering frequency of vibrations

•Be able to explain and evaluate how the learning of birdsong is investigated

Originally people tried to write birdsongs as music

Thorpe developed the time frequency sound spectrogram also known sonogram.

The terms ‘note’ and ‘element’ are interchangeable – and refer to the most basic unit of the song – a continuous sound in the spectrogram that may contain many frequencies. Notes are grouped into syllables, and these in turn are grouped into phrases. Different sorts of phrases have descriptive names like ‘whistle’, ‘trill’ and ‘buzz’. A phrase can consist of just a single syllable or even a single note.

Do birds learn from others

He reared chaffinch bird eggs in isolation in sound proof boxes so he could control the sounds. He would play a tune on a speaker called the teacher song.

1. He would play an adult birdson for the juvenile and see if the juvenile was able to play the song in the future. The experiment found that they had very similar sounding song practically identical.

2. When the chaffinch is kept in complete sound isolation it still sings a song but it is not similar to the original species song. When analysing the sonogram it has similar sounds but they are not completely identical. The song is not refined.

3. If the chaffinch is kept in isolation and is given a tree pipit bird species song , there are similarities between the chaffinch and tree pipit song which shows that it did have an effect on the song produced.

This research suggests birds have an innate template, young birds also have a preference for their own species. If a bird did not have a tutor during the critical period it is unable to reproduce the song.

•Be able to explain Marler’s observation on how birds crystallize their songs and link this to neuronal changes

He used finches sparrows and caries. Young birds heartbeat increases.

There are 3 stages of song development. If a bird hatches in spring it is in the sensory phase were it listens to tutor song. In the sensorimotor phase can be split into subsong which is a soft variable rambling syllables and plastic song which is rehearsaa;, syllables and phrases of tutor song start to become recognisable.

The last phase is the crystallized phase where the song has characteristic volume, duration, syllables and phrase order of species specific turor song. Song remains unchanged but there are species differences.

	Criado por Tino Mutasa mais de 9 anos atrás

2nd Yeat Behavioural Neurobiology (Birdsong) Notas sobre Birdsong Lecture 7, criado por Tino Mutasa em 03-04-2017.