Lessons from vervets and macaques

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Lessons from vervets and macaques

• MSc ACSB module 2005/06
• Session 3

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Vervet predator alarm calls

• 3 main types of predator, and 3 alarm calls
• Eagle gets a Cough,
• Snake gets a Chutter
• Leopard gets a Bark
• Hearers behave appropriately when they hear each
  of these types of call (run down from treetops /
  walk carefully / run up into trees)
• Do hearers understand the call, or cue their
  response from the behaviour of the caller?

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Vervet calls on www

• http//www.wjh.harvard.edu/mnkylab/media/vervetca
  lls.html

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Vervet alarm calls provide information about
environment

• Film response to plausible taped call no real
  caller to give hearers a clue to the appropriate
  response from his behaviour
• 3 responses given in appropriate contexts with
  just the information in the call itself
• So monkeys respond to acoustic signals, not just
  to signallers concurrent behaviour
• Signals provide information about environment,
  not callers mood / motivational state (e.g. fear)

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Ontogeny of vervet predator calls

• Are monkey vocalisations learned? Not in squirrel
  monkey, perhaps in X-fostered japanese rhesus
  macaque food-coos
• Vervet infants give alarms to appropriate class
  of stimuli, but too wide a spread
• Leopard to many large ground animals
• Eagle to birds of all sorts
• Snake to sticks and other long thin objects
• As grow up, they focus alarms down on the real
  predators, the class-members that spell danger

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Vervet call development (2)
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Vervet call development (3)

• Narrowing down of call triggers may depend on
  response from adults take up and repeat alarm to
  a real hazard, ignore it to a harmless stimulus
• Responses to alarm calls are not fully adult
• Initially respond after looking at an adult which
  has started to respond
• More often show adult-like response when near
  mother than when mother has wandered away
• Vervets use "wrrr" to indicate threat from
  another group experience shapes correct use over
  1st two years of life (earlier if more frequently
  in contact with other groups)

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Vervet call development (4)
Probability of adult alarm call after infant has
given eagle alarm to different species
Infants give more adult like responses to alarm
call playback as they grow older
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Involuntary or voluntary?

• High ranking vervets call more often, and are
  more often the first to call. Dont scan for
  predators more often. So subordinates must ?
  also detect predator but omit call
• Females call more readily if kin present
• Captive males call more when female companion(s)
  than when companion is male
• Never call eagle when should say leopard

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Is this alarm call system unique?

• Calls provide info about dangers, not level of
  fear
• Vervet monkey grunts (Cheney Seyfarth)
• Can't be distinguished by ear by humans
• 4 types DomgtSub, SubgtDom, Move Into Open, see
  Another Group
• Difference in response to taped grunts indicates
  monkeys can separate them, appropriate
  information conveyed, e.g.
• MIO listener looks towards loudspeaker
• AG looks away towards where loudspeaker points

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Vervet grunts
16 acoustic parameters from one female 82
correct classification of her calls and others'
calls
Vervet grunts are spectrographically distinct but
cannot be distinguished by ear by humans
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Rhesus monkey screams

• Rhesus pigtail screams studied by Gouzoules
• Rhesus has 5 types of scream code for
• Rank of the opponent
• Whether a relative (safer) or non-kin (risky)
• Whether or not any physical contact
• Pigtail has 4 types of scream

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Rhesus screams (2)

• High rank, contact
• Low rank, no contact
• Relative, or
• High, no contact
• Relative
• High rank, no contact

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Interim conclusions

• In Vervet alarm call system, information is
  encoded in specific calls, coding is partly
  pre-wired but refined by experience
• Several other call systems which communicate
  environmental information
• Kitui used leopard call (sans leopard) to halt a
  fight that his troop were losing but then
  walked across ground repeating the call, which
  made it plain to humans that there was no real
  danger

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What information is in a call?

• Do primates lump-together calls that refer to the
  same thing?
• Habituation
• Do primates learn about calls, or about mental
  state of caller?
• Are changes in risk tied to particular threat?
• Do callers aim to inform or get specific response?

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Rhesus food calls

• 4 food calls
• Warble, Harmonic Arch (Good food)
• Coos, Grunts (low-quality food)
• S1 and S2 initially elicit orientation
• Habituate S1, then test S2 where S2 may be
  different signal for same quality of food, or
  different signal for different quality food

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Hausers results

• Hauser, 1998, Anim Behav 55, 1647-1658
• Habituate response to one HQ food call
• Eliminates response to other HQ call
• Leaves intact response to LQ calls
• Habituate response to one LQ food call
• Leaves intact responses to HQ food calls

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Cheney Seyfarth - Vervet

• Inter-group calls
• Wrr (low arousal just spotted) Chutter (high
  arousal scrap going on or likely)
• Habituation paradigm
• Test Chutter habituate Wrr (same ) re-test
  Chutter
• Decreased response if all 3 stimuli for same
  hazard, from same , not if different monkeys
  calls used
• Implications
• know that A and B represent the same threat,
  conclude that 5 has become unreliable about
  other groups
• No decrement if calls represent different threats

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Superb staring alarms

• Aerial and ground predator alarms
• Test starling alarms habituate vervet eagle
  alarm test starling alarms again
• Decreased response to starling eagle alarm
• No decrement for starling ground predator call
• Have learned to be sceptical about (any) warnings
  about aerial predators, not habituated to vervet
  coughs in particular

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What does caller aim to achieve?

• In Cameroon, vervets attacked by feral dogs
• Dogs trigger leopard alarm, troop runs into
  trees
• Elsewhere, hunted by men with dogs guns
• Leopard alarm would attract attention shot
• Dogs elicit quiet call that allows troop to flee
  silently
• Monkey link signals to the action it needs to
  achieve

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Limits on understanding

• Kitui used a bark to stop fight (deception?), but
  then walked across ground showing that there was
  probably no leopard
• Vervets cant recognise other indirect cues to
  danger snake track on ground, antelope carcass
  stored in tree which signals that a leopard is
  nearby

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References session 6

• Cheney Seyfarth (1992) Behavioral and Brain
  Sciences, 15, 135-147 (commentary 147-182)
• Cheney Seyfarth (1990) How monkeys see the
  world, Ch. 3-6.
• Seyfarth Cheney (2003) Meaning and emotion in
  animal vocalizations. Annals of the New York
  Academy of Sciences, 1000, 32-55.
• Hauser (1997) The evolution of communication.
  Ch. 5, 7