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- Highly variable site to site, and throughout a given year.
- Studies in Yucatan, Mexico show the following patterns:
- Major activities: feeding, preening, and resting. Other activities are associated with locomotion, aggression, alertness, and comfort.
- During the breeding season, energy is diverted to courtship, nesting, and incubation.
- Most feeding occurs just prior to courtship, suggesting that stored reserves are used during synchronous breeding activities.
Tend to not defend their nest or area around themselves very aggressively
Displays of aggression (Rooth 1965)
- Bill-fighting: both individuals aggressive; face each other and try to bite the head/beak area of opponent
- Chasing: one chases another; retreating bird stretches neck out straight; chaser pecks at tail end of other.
- Threatening: face each other with outstretched necks and open mouths, sometimes with growling vocalizations.
- Mate protection: If a mated pair comes in contact with another, the male will become aggressive, defending the female.
- Highly social, forming large colonies with tens or hundreds of thousands of individuals.
- Large numbers provide security.
- Little competition for food -algae and invertebrates tend to be concetrated and abundant.
- Done in groups to synchronize breeding in a colony.
- Wing salute- wings are spread for a few seconds, showing a flash of color; the neck is stretched out and the tail is flipped up. Usually followed by head twist to the back.
- Wing-leg stretch- simultaneous stretch of one wing and leg on the same side.
- Twist-preening- rapidly alternating between stretching neck forward and twisting head around to the back, bill touching shoulders
- Head flagging- head held high, neck stretched, head slowly and rhythmically turns left and right
- Head shaking- bend neck, head waggles side to side.
- Marching- tight group marches together in one direction, then suddenly flips around and walks the other direction.
- Bowing: neck stretched forward, and angled down toward the water; wings are open about a third
- Most important function: to keep flock together
- Very similar to geese
- Honking sound while flying and on the ground
- A "low gabbling noise" from groups during feeding
- Grunting, growling noises given during breeding or aggressive displays
- Recent studies of managed care populations by Boylan (2000) show the following:
- There are many more vocalizations than previously thought
- There are four main components to the calls: repetitive, tonal, "buzzy", and a combination repetitive/tonal
- Walk and run easily when threatened. Take-off requires a short run, facing wind with wings flapping.
- Fly with necks and legs outstretched, similar to cranes and storks.
- Continuous, rapid flapping, reaching speeds of 50-60 km/h (31-37 mi/hr).
- Fly in loose "v" or diagonal line, similar to geese and cranes.
- Tend to be fairly nomadic throughout the year as they follow shifting resources.
- Move to different patches within sites; move between sites up to hundreds of km apart.
- Generally, non-migratory birds.
- Those that do migrate, move between summer breeding sites and winter non-breeding areas.
- In Bonaire, migration does not occur all at once, but in successive waves.
- Galapagos population sedentary.
del Hoyo et al. (1992)
Espino-Barros & Baldassarre (1989a)
Espino-Barros & Baldassarre (1989b)
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Fact Sheet Index
Fact sheet index, San Diego Zoo Wildlife Alliance Library
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