Foraging behaviors of dolphins;an example of beach hunting in Monkey Mia-Australia

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Foraging behaviors of dolphinsan example of
beach huntingin Monkey Mia-Australia
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Introduction

• ?lobtail and bubble net feeding in humpback
  whales
• ?bird-associated foraging and lunge feeding by
  minke whales
• ?cooperative hunting and strand feeding by killer
  whales
• ?Humpback dolphins push fish onto exposed sand
  banks at low tide and surge partially onto the
  banks to catch them

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But what about bottlenose dolphins (Tursiops
truncatus) ?

• ? strand-feeding  bottlenose dolphins in the
  southeastern United States
• ?bottlenose dolphins, in the southeastern United
  States, the Colorado River Delta and Portugal
  ,use estuarine mud flats in order to hunt
• ...but there are both inter- and intrapopulation
  variability.

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An example of beach hunting,a rare foraging
behavior, by wild bottlenosedolphins (Sergeant
and al.,2005)
Cape Peron, Peron Peninsula, Shark Bay, Western
Australia
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• 13 distinct foraging tactics
• Beach hunting
• frequent fast swims in shallow water , creating
  a trail of water off the dorsal fin, as dolphins
  chase individual fish parallel to and then onto
  the beach surface.
• partial beaching
• surging out of the water onto the beach with the
  ventrum touching the substrate FREQUENTLY
• full beaching
• the dolphin emerges almost completely out onto
  the
• beach OCCASIONNALY

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• four adult females and their offspring.
• Cooperative and coordinated foraging was not
  observed
• incoming tides and high tides,
• stranding risk lower during this time
• dolphins forage individually, chasing singular
  prey for hundreds of metres parallel to and onto
  the beach.

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• Some dolphins are more specialized in beach
  hunting than other dolphins...
• One female Xmore time in shallow beach
  habitats,
• specializes in beach hunting
• higher success rate
• more solitary.
• Another female Y Less time in shallow beach
  habitats,
• specializes in another foraging tactic
• lower success rate
• more social.
• gt dolphins overlapping in range can partition
  niche use, and may also show that once a dolphin
  learns one tactic it is not limited to that
  tactic alone.

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The learning of calves

• No calves were ever observed full beaching or
  definitely catching fish while beach hunting.
• Although beach hunting has been observed in one
  calf in the first year, full beaching was not
  observed for at least the first 5 years.
• gtcomplete development of beach hunting takes
  longer than other tactics, possibly because its
  complexity requires lengthy learning periods
  and (or) because calves are continuing to develop
  physically

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• In spite of the presence of mother/calf
  associations, mothers were never observed
  attending to their calves or altering their
  foraging behavior in response to calf presence
  during beach hunting, presenting no evidence for
  teaching.
• Full beaching is a late-developing behavior
  compared with the majority of foraging behaviors
  used in Shark Bay
• Complex foraging in Shark Bay bottlenose dolphins
  may help explain their unusually long dependency
  periods (3 6 years) and the sizable overlap
  between independent foraging and nursing

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Conclusion

• Beach hunting corresponds with tidal state and
  habitat use, develops later than other foraging
  behaviors, does not occur strictly within
  matrilines, and may involve social learning (but
  not teaching)
• The challenge or even danger of becoming stuck on
  the beach is consistent with the fact that beach
  hunting occurs more during incoming tide, which
  could lower stranding risk

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Thanks for your attention