MARB 403 Lab 2
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Signature Whistles
Authors:
- Vincent M. Janik
- Laela S. Sayigh
First discovered when captive dolphins isolated for medical attention
defined: most common whistle when in isolation
Tursiops signature is important
common use: animal identification maintain cohesion
first studies on captive dolphins
studied in wild: 52% of whistles were signature
observed send more whistles when one member isolated itself
in wild,
- during reunions
- similar among male alliances
Tyack: whistle replication "vocalight" on when member is speaking
Whistle Rates of Wild Bottlenose Dolphins: Influences of Group Size and Behavior
Authors:
- Vincent M. Janik
- Nicola J. Quick
Acoustics: prduction of sound
- echolocation
- prey manipulation (balls of fish)
- communication
Two classes
- long elaborate song displays (males use to attract females)
- non-song one receiver or a small group of receivers, food, alarm, maintaining contact
Calls can be masked (drowned out) by surrounding members depending on group size
- requires adaptation through development of signature whistles
1/2 of wistles heard are signature whistles, other 1/2 ???
Purpose of Study
Measure whistle rates of wild bottlenose dolphins (do they change according to group size)
NE coast of Scotland
Difficulty: determine where whistle came from
Passive recording and observation
Focal follows, photo ID, watching and behavior sampling; 4 hydrophones
2-minute intervals
localized and caller position and activity
Rate per individual per 2 minutes
Results
about 1/2 were categorized into usable behaviors
- nonpolarized movement
- travel
- socialization
Whistled less in larger groups and while traveling
group size of 15 to 20 whistled the most
Discussion
Behavior and group size affected individual dolphin's whistle rates
surface travel had almost no vocalization
Increased rates during nonpolarized movement from
- remaining in contact with individuals
- random movements
- transition between behaviors
Increased rates during socializing may be from
- communicating to social associates
- maintaining contact
Larger groups made fewer whistles (probably to prevent masking)
Milling Explained
Nonpolarized movement when members move in all such random directions
When dolphins move for traveling purposes, they usually move in a single, uniform direction
Discussion
in stranding,
- Vocalizations are frequent from younger animals than older animals
- signal of distress?
- gets quieter as time goes on
4-hydrophone array: able to determine direction to dolphin making communication
Are group decision democratic? representative?
(Dr. Wuersig's right whale story...?)
Surrogate mother: orca calf with bottlenose mother...
Communication if in isolation? from birth? bonded to other species (e.g. surrogate mother or human)?