Bird song

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Bird song

• MSc ACSB module 2006/07
• SB Session 9 (week 9)

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Bird song is used

• As a territorial proclamation for territorial
  defence, mate attraction
• Song birds (oscines) learn their song in
  non-oscines, the whole vocal repertoire is innate
• The learning of song may parallel the learning of
  language but we also need to consider the
  function explanation for learning (rather than
  hard wiring), and the neural control of song

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Chaffinch Song (Thorpe)

• Learned over first year, even from tutor-tape
  isolation-reared song much simplified
• Learned variations in song in different males

Normal
Single isolate
Group isolate
Tutor tape with end-in-middle
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Chaffinch song learning

• Learned during critical period (now sensitive
  period) closed-ended learning
• Proper song not produced without this experience
• But not standard unconstrained learning will
  only learn own species song, very rarely a
  foreign element
• So constraints on learning Lorenz spoke of the
  innate schoolmarm
• What kind of genetic instructions produce this
  constrained learning, and why?

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White Crowned Sparrow song

• White crowned sparrow songs vary with locality
  around San Francisco bay
• Dialects learned during a males early
  post-fledging life (to 50 days of age)
• After this point, migrants start to travel south
  through region and birds no longer hear just
  local dialect

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Why have a flexible learned signal which other
birds can hard-wire?

• Cant be because complex song is too hard to
  achieve by hard-wiring
• Time of end of sensitive period in WCS suggests
  that learning is designed to maintain the
  dialect-system
• Nottebohm on the Chingolo song types stable
  over vast areas of flat pampas, but change
  rapidly on hills as altitude increases.
• ?Ensures that genes adapting to higher-altitude
  environment are not diluted by mating with birds
  from outside the local population, i.e. with
  plains-birds.

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Parallels with language?

• Nottebohm (72) drew tentative parallels with
  human languages it may also be important to
  constrain mate choice within human group
• Baker found some dialect-linked differences in
  WCS gene frequencies, and evidence of reduced
  gene flow between neighbouring populations
• Dialect may influence the place where birds
  settle where the local dialect is the one they
  heard when young

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No support for the Genetic Adaptation Hypothesis
(GAH) in the Chingolo

• Marler Slabbekorn (2004) Natures Music, box
  p. 210
• Handford Nottebohm found no evidence to support
  the GAH instead
• Dialects changed in relationship to habitat types
  in way suggesting adaptation to the
  sound-transmission characteristics of particular
  habitats

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Was the emphasis on dialects misdirected?

• Jenkins (1985)
• Baker Cunningham reify dialect and then seek
  a function for it, whereas the key evolutionary
  question in this field is, Why did song learning
  evolve?
• We cannot hope to discover what birds do learn
  or re-learn in the wild if our experiments deny
  them the basic motivating stimulus for learning
  competition for resources
• Gaining a territory requires a bird to stand
  its ground, stake a claim, and attack males
  competing for the same mate. What do birds learn
  under these conditions, and when do they stop
  learning?

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Nowicki Searcy developmental stability and
song learning

• Individuals differ in developmental stability
  the extent to which good genes buffer them
  during critical phases of growth (e.g. measured
  by FA)
• NS emphasize the role of songs in revealing male
  quality females prefer males with large
  repertoires, etc.

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Developmental stability (2)

• Song repertoire size, copying accuracy, etc.,
  depends on growth of CNS structures, e.g., the
  HVC, during periods of development in which
  nutritional and other stresses can occur.
• Song repertoire, copying accuracy can provide
  females with an index of the males early
  developmental stability in face of stressors that
  acted in juvenile period, long before the female
  makes her assessment

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Developmental stability (3)

• Studies of e.g. food restriction do show effects
  on song characteristics, e.g. copying accuracy
• So having an open rather than closed
  instruction-set for song development could permit
  bird-song to provide a long-distance index of
  male quality
• To discuss possible parallels with human
  language development

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Two zebra finch songs

• Source Cornell University at
• http//instruct1.cit.cornell.edu/courses/bionb424/
  students/smc67/behavior.html

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Developmental stability (4)

• Zebra finch
• Spencer et al (2003) Hormones Behaviour 44,
  132-129 dietary restriction and elevated
  cortesol during development ? songs that were
  shorter, with reduced complexity
• Spencer et al (2005) BES 58, 423-428. Females
  given choice of songs from males stressed vs.
  non-stressed during development showed preference
  for song of non-stressed males
• Bengalese finch
• Soma et al (2005) Ethology 112, 1071-1078 Early
  rearing experiences (reflecting brood size, sex
  ratio) affects song complexity, complexity is
  reduced in males growing up in male-biased or
  larger broods
• Okanoya (2004) Ann. NY Acad. Sci. 1016 724-735
  Bengalese finch song more complex than that of
  wild white-rumped munia females prefer BF song
  to munia song

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Developmental stability (5)

• Spencer et al (2005) PRSB 272, 2037-2043
• Canaries infected with malaria as juveniles
• Develop simpler adult song, and
• Show 36 smaller HVC
• Song sparrows (NS 2004) hand-reared with
  nutritional stress copied tape tutor notes less
  accurately females prefer well-learned to
  poorly-learned songs

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Variety in song learning

• NSs idea cant explain all variations in detail
• Cardinals both MF sing, sensitive periods 71d
  F, 187d M Ms will be able to included phrases
  learned where settle, F keep to natal dialect
• Many spp. learn local song, or taped song of
  their own (but not from other) species - e.g.
  White Crowned Sparrow but Zebra finch learns
  only (foster-) fathers song
• Mynah mimics human speech Lyrebird mimics many
  sounds

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Studies of the song-learning process (1)

• Early sensitive period (50d in WCS), later
  sub-song, plastic song, crystallised song
• End of sensitive period may depend on relevant
  input ends sooner if hear suitable song,
  delayed if deprived

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Song learning (2)

• Parsing syllables in WC sparrow song learning
  ABCDE structure can be reconstructed if tutored
  with disconnected syllable-pairs that never
  reveal the whole order, e.g. DE, AB, CD, BC
• If present ED, BA, DC, CB, reconstruct EDCBA
• If present individual syllables rather than
  pairs, final song bears little resemblance to
  normal song structure
• Rose et al. (2004) Nature 432, 753-758

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Song learning (3)

• Song sparrow complex song
• Swamp sparrow simple trill
• White crowned sparrow intermediate
• Used in cross-learning studies

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Song-learning (4)

• Nature of learning-template reflects
  song-syllables and song-structure
• Swamp Sparrow learns Swamp-S syllables even if
  Song-S structure
• Song Sparrow learns Song-S syllables in Swamp-S
  structure (trill) AND Swamp-S syllables if put
  into Song-S structure

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Song control in brain

• Birdsong is control-led by brain nuclei including
  HVC, RA and Area X
• The brain sends (song-)motor commands via the
  12th cranial nerve (hypoglossal nerve) to the
  syrinx

NIf
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Lateralised control of birdsong

• Birdsong controlled by brain nuclei and motor
  commands down XII (hypoglossal) nerve
• Nottebohm cut XII nerve unilaterally
• L abolishes all major components of song
• R only minor losses

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Song control (2)

• HVC (higher vocal centre is major control centre
  for song)
• L HVC lesions have major impact, R HVC do not.
• Left lateral control of the major/ complex sounds
  in the song many species, but not all zebra
  finch has R sided control
• Could the L brain be specialised for control of
  complex motor patterns?

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Song control systems

• Crystallised song may not be crystallised
• Zebra finch syllables lose form after deafening,

NIf

• No loss of form if deafen LMAN lesion
• LMAN flags discrepancy (heard song ? template),
  sends instruction to vary song
• Deafen -gt mismatch -gt signal plastic Deaf
  LMAN-X -gt no signal -gt remains stable
• Okanoya NIf -gt complex syntax in domestic
  Bengalese finch compared to wild ancestor

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References

• Hauser (1997) Evolution of communication. Ch.
  5.2.1
• Brainard Doupe (2004) Nature, 417, 351-358
• Beecher Brenowitz (2005) TREE, 20, 143-149
• Brenowitz Beecher (2005) TINS, 28, 127-132
• Marler (1981) TINS 4, 88-94
• Nowicki Searcy (2004) Ann. New York Acad. Sci.
  1016 704-723
• Okanoya (2004) Ann. New York Acad. Sci. 1016
  724-735
• Marler Slabbekorn (2004) Natures Music