ANTHROP 3HI3 Lecture Notes - Lecture 10: Railways Act 1921, Horse-Fly, Coral Reef Fish
22 Feb 2018
School
Department
Course
Professor
Document Summary
Benefits: protection from weather (ex; huddling for warmth, aerodynamic advantages in locomotion, reducing predation, improving foraging success. Summary of some anti-predator and foraging benefits of grouping. Per individual was lower in a larger colony: so the advantage of dilution outweighed the cost of greater conspicuousness. Synchrony in time: predator swamping: synchrony in time can also dilute predator attacks per individual prey. Individuals in groups may be safer from attack because the predator has difficulty in focusing on one target as individuals keep moving across the predator(cid:495)s line of sight. Indirect evidence for confusion effect: predators target odd-colored individuals in a group to possibly identify them easier and overcome the confusion effect with perch. Prey may sometimes actively defend themselves by attacking/mobbing a predator and grouping may enhance defense. Example: nesting black-headed gulls: mob crows who come into their colony in search of eggs/chicks, gulls mob grows in the center of the colony.
