Chapter 41

ANIMAL BEHAVIOR

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 BehaviorInborn 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 BehaviorBehavior 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 ConditioningAnimal 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. ImprintingAnimal 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 LearningAnimal 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 Behavior1. Orientation and Navigation

Many animals orient (move in a specific direction) and navigate (follow a specific course).

Male moths flying toward pheromone-releasing females.

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. AggressionOften 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: large or small defended against all members of the

species or members of one sex defended year round or seasonally

Ownership is displayed by marking boundaries: pheromones scent glands urine dung

Dominance hierarchy - a social ranking of adult members of the same sex.

Common among vertebrates (domestic hens, wolves).

3. Mating BehaviorMany animals have elaborate,

species- specific 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. polygyny - 1 / many ’s polyandry - 1 / many ‘s polygynandry - both sexes have

multiple partners.

4. AltruismBehavior 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 LivingMany 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

chemical (alarm pheromone of ants) auditory (sperm whales; elephants) tactile (grooming behaviors of nonhuman

primates) 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

Naked mole rats

Honeybees