ANIMAL BEHAVIOR Chapter 41 Ethology the study of

ANIMAL BEHAVIOR Chapter 41

Ethology - the study of animal behavior. Ethologists are particularly interested in adaptive behaviors. Some adaptive behaviors are primarily innate, while others are primarily learned.

A. Innate Behavior Inborn behavior that is largely genetically determined. Ex. escape or defensive behaviors Many innate behaviors are stereotyped (all members of a species perform the behavior identically). Stereotyped behavioral sequences are called fixed action patterns (FAPs). Ex. egg retrieving behavior of graylag goose

Once begun, FAPs continue to completion, even without appropriate feedback.

FAPs are triggered by a specific stimulus called the releaser (sign stimulus). What is releaser for graylag goose egg retrieval? Releasers can be: ] visual (red underbelly of stickleback fish; light flashes of fireflies; gaping mouth of baby birds) ] auditory (sounds of mosquitoes & crickets) ] tactile (male prodding of female stickleback) ] chemical (pheromones)

Supernormal releaser - a model that exaggerates a releaser; elicits a stronger response than does the natural object. Herring gull chicks obtain food from their mother by pecking on her bill. Normal releaser is red spot on an oblong object. Supernormal releaser is an oblong object that is totally red or has red stripes.

B. Learned Behavior modified by experience. Types of Learning: 1. Habituation (simplest form) Animal learns to ignore irrelevant stimuli. Young chicks learn to ignore falling leaves & silhouettes of non-predatory birds. ] Birds learn to ignore scarecrow. ] Mothers learn to ignore noisy children. ]

2. Classical Conditioning Animal learns to associate a new stimulus (conditioned stimulus) with a reward or punishment. Dog associates the sound of a bell with food. [Pavlov’s dogs] ] Ducks associate people with food. ] ] Bears associate cars with food. Extinction - loss of a conditioned response.

3. Operant Conditioning (trial-and-error) Animal learns to associate one of its own behaviors with a reward (positive reinforcement) or punishment (negative reinforcement). Used extensively by animal trainers. Coyote learns to avoid porcupines. ] Rat learns to press a lever to obtain food. ] Parrot learns to ride a scooter. ]

4. Imprinting Animal learns during a limited time period (critical period). ] Newly hatched chicks, goslings or ducklings learn to identify the first moving object they see as “mother”. (Konrad Lorenz) Baby birds learn species-specific songs. ] Mother goat learns to identify her kid’s odor. ]

5. Insight Learning (reasoning) Animal applies prior learning to new situations without trial-and-error activities. Rare; seen mostly in primates. Chimpanzee figures out how to stack boxes to reach bananas hanging from the ceiling. ] Human child figures out how to build a vehicle by placing a box on roller skates. ]

6. Latent Learning Animal uses past observations to perform a new activity; occurs without obvious punishment or reward. Rats learn to negotiate a maze more rapidly if they’ve been previously exposed to it. ] Wild animals learn details of their range during daily explorations. ] Predators learn hunting tactics by observing their mother. ]

Most animal behaviors have both genetic (nature) and environmental (nurture) components. C. Types of Behavior 1. Orientation and Navigation Many animals orient (move in a specific direction) and navigate (follow a specific course). F Male moths flying toward pheromonereleasing females. F Bees flying to & from nectar sources.

The most complex orientation & navigation behaviors are seen in migrating animals. Migration – a regularly repeated journey from one specific geographic region to another. Bird migrations

Most migrating species use environmental cues for orientation & navigation. ] sun & stars ] earth’s magnetic field ] sounds, odors, landmarks

2. Aggression Often displayed when individuals are competing for the same resources (mates, food, shelter, nesting sites). Aggression is minimized by territoriality and dominance hierarchies. ] Territoriality - behavior that defends one’s territory. Common among insects, birds & mammals.

Territories can be: F large or small F defended against all members of the species or members of one sex F defended year round or seasonally Ownership is displayed by marking boundaries: F pheromones F scent F urine F dung glands

] Dominance hierarchy - a social ranking of adult members of the same sex. Common among vertebrates (domestic hens, wolves).

3. Mating Behavior Many animals have elaborate, speciesspecific courtship displays (prevents interspecific mating).

Mating Systems: ] Monogamy - male & female are paired for a period of time (days, season, lifetime); tend to care for & protect young. Ex. elephant shrews & Bewick’s swans ] Polygamy - member of one sex mates with several members of opposite sex; members are usually sexually dimorphic. F polygyny - 1 / many ’s F polyandry - 1 / many ‘s F polygynandry - both sexes have multiple partners.

4. Altruism Behavior that increases another’s fitness at the expense of one’s own fitness; frequently seen in complex social groups (honeybees, naked mole rats). Altruism is explained by kin selection. By helping a relative survive and reproduce, the altruistic member ensures that some of their genes are passed to the next generation.

D. Group Living Many animals live in groups. Advantages conserve heat or moisture ] better defense (confusion, mobbing) ] enhanced reproductive success ] improved food acquisition ] improved learning ] Disadvantages rapid depletion of limited food supply ] spread of disease ]

Eusocial animals exhibit 4 characteristics: ] cooperative care of young ] overlapping generations ] division of labor ] communication F chemical (alarm pheromone of ants) F auditory (sperm whales; elephants) F tactile (grooming behaviors of nonhuman primates) F visual (round & waggle dances of honeybees)

Round dance indicates that food is close to the hive. Waggle dance indicates that food is far away: • orientation of the “run” relates direction • frequency of waggles relates distance

Examples of eusocial animals: Snapping shrimp Honeybees Naked mole rats