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Animal BehaviorChapter 51

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Why study behavior?

Ethology— the study of behavior

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Ethologypioneers in the study of animal behavior

Niko TinbergenKarl von Frisch

1941 | 1973

Konrad Lorenz

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What is behavior? Behavior

Defined as observable and coordinated responses to environmental stimuli. Result of genetic & environmental factors

Innate Behaviors inherited, “instinctive” automatic & consistent “Built-in”, no “learning curve” Despite different environments,

all individuals exhibit the behavior Ex. early survival, reproduction, kinesis, taxis

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Evolutionary perspective Learned behaviors

Modified by experience Variable, changeable

change with experience & environment

Flexible with a complex & changing environment

Ability to learn is inherited, but the behavior develops during animal’s lifetime

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Levels of Behavioral Analysis Proximate causes

Immediate stimulus & mechanism Genetic & environmental interaction Sensory motor mechanisms “how” & “what” questions

Ultimate causes evolutionary significance how does behavior

contribute to survival & reproduction

“why” questions

male songbird what triggers singing?

how does he sing? why does he sing?

male songbird what triggers singing?

how does he sing? why does he sing?

how does daylength influence breeding? why do cranes breed in spring?

how does daylength influence breeding? why do cranes breed in spring?

Courtship behavior in cranes what…how… & why questions

Courtship behavior in cranes what…how… & why questions

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Ex. Most people like fatty foods What is the proximate cause?

What is the ultimate cause?

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Answers Proximate cause-Because it tastes good

  Ultimate cause- Because it is high in

calories which are the stuff the body needs to function

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Innate Behaviors-developmentally fixed Taxis Kinesis Migration FAP Animal Signals & Communication

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Innate Behaviors-Taxis Automatic response toward or away from a

stimulus. Automatic movement toward (positive taxis) or

from away (negative taxis) a stimulus phototaxis Chemotaxis

Examples: Trout are and swim upstream so as not to be

swept away.

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A change in the activity rate in response to a stimulus.

Randomly directed, unlike taxis. Example:

Sow bugs are more active in dry areas and less in humid ones; this keeps them in moist environments.

Innate Behaviors- Kinesis

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Innate behavior: Fixed action patterns (FAP) Unlearned Usually carried to completion once started Triggered by a sign stimulus

male sticklebacks exhibit aggressive territoriality

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Fixed Action Patterns (FAP)

Do humans exhibit Fixed Action Patterns? The “eyebrow-flash”

Digger wasp

Human babies always smile at a

mask with two dark spots for

eyes.

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Fixed Action Patterns Examples

Male stickleback fish will show aggression toward any shape that has a red area.

attack on red belly stimuluscourt on swollen belly stimulus

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Figure 51.3 Classic demonstration of innate behavior

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Complex Innate behaviors Migration

“migratory restlessness” seen in birds bred & raised in captivity

Migration is learned, but how to learn them is innate Celestial navigation- by sun, stars, Earth magnetic

fields

Monarchmigration

Sandpiper

ancient fly-ways

Bobolink Golden plover

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Examples of Migration Monarch butterflies from our area migrate to

Mexico in the fall and the next generation flies north in the spring.

Snow geese fly 2,700 km from James Bay, Canada to Louisiana nonstop in 60 hours.

The green sea turtle migrates 2,200 km across the Atlantic ocean from the east coast of South America to Ascension Island (10 km across) every 2-3 years where the adult females lay eggs.

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Biological Rhythms & Clocks Circadian Rhythms “Sleep, wake cycle”

Humans~about 24 hours long Drosophila the normal clock is 24.2 hrs Mutant flies have cycles of 19 & 28 hrs.

Diurnal —active during the day Nocturnal —active during hours of darkness Crepuscular —having greatest activity during

twilight hours or at dawn or both

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Biological Rhythms & Clocks Lunar cycles Ex.

Grunion swarm from April-June when the spring tides occur

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Biological Rhythms & Clocks What controls the biological clock? No single mechanism—an interaction of a

number of biochemical processes The pineal gland is thought to play a role

in the timing system of rats, birds and some other vertebrates.

In mammals, regions of the hypothalamus are involved.

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Biological Rhythms & Clocks How much is internal and how much is

governed by external clues? Answer: There is usually a strong

endogenous (internal) component, but an exogenous (external) cue is necessary to keep the behavior properly timed in the real world.

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Animal Signals & Communication An action by a sender that influences the

behavior of a receiver. Does not have to be purposeful Ex. bat sound pulses influence moth

evasive behavior.

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Communication: Chemical Works both day and night

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Social interaction requires communication Pheromones

chemical signal that stimulates a response from other individuals

Ex. Female moths secrete chemicals which attract males.

Cheetahs and other cats mark their territory with urine, feces, and anal gland secretions.

alarm pheromones sex pheromones

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Pheromones

Spider using moth sex pheromones, as allomones, to lure its prey

Female mosquito use CO2 concentrations to locate victims

marking territory

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Communication: Auditory Faster than chemical and also effective both

night and day. Can be modified by loudness, pattern,

duration, and repetition. Ex. Male crickets have calls and birds may

have one song for courting, another for distress, and still another for marking territories.

Humpback whales have complicated songs. Nonhuman primates have up to 40 different

vocalizations.

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Communication by song Bird song

species identification & mating ritual mixed learned & innate critical learning period

Insect song mating ritual & song innate, genetically

controlled

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Communication: Tactile Occurs when one animal touches

another. Ex. A male leopard nuzzles a female’s

neck to calm her and to stimulate her willingness to mate.

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Honey bee communication dance to communicate

location of food source waggle dance Discovered by Karl von Frisch

in the 1940s. Waggle dance indicates both distance to and direction of food.

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Communication: Visual Most often used by species that are active

during the day. Contests between males involve threat

postures and possibly prevent fighting. Ex. Male birds often put on courtship dances

to attract females. Much human communication is nonverbal

such as smiling, blushing, body posture.

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Learned Behavior: Modified behaviors by experience

Habituation Imprinting Associative learning

Classical conditioning Operant conditioning

Cognition

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Learning: Habituation Loss of response to stimulus

“Cry-wolf” effect Decrease in response to

repeated occurrences of stimulus

enables animals to disregard unimportant stimuli ex: falling leaves not

triggering fear response in baby birds

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Innate & Learning: Imprinting Learning to form social attachments at a

specific sensitive (critical ) period both learning & innate components

Konrad Lorenz- spent time with geese hours after hatched

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Figure 51.9 Imprinting: Konrad Lorenz with imprinted geese

Konrad Lorenz

ImprintingImprinting

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Conservation biologists have taken advantage of imprinting by young whooping cranes as a means to teach the birds a migration route. A pilot wearing a crane suit in an Ultralight plane acts as a surrogate parent.

Conservation

Wattled crane conservation

teaching cranes to migrate

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Associative learning Learning to associate

a stimulus with a consequence Operant conditioning

BF Skinner Trial & error learningAssociate behavior with reward or punishment

Classical conditioningPavlovian conditioningAssociate stimuli with reward or punishment

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Operant Conditioning

•Gradual strengthening of stimulus-response connections.•Examples:

• Teaching an animal a trick by rewarding correct behavior with affection or food.

• B.F. Skinner’s experiments• Rats connect sugar treat with pressing a lever.

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Operant conditioning Skinner box

mouse learns to associate behavior (pressing lever) with reward (food pellet)

B. F. Skinner

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Critical period

As a brood parasite, the Cuckoo never learn the song of their species as a nestling. Song development is totally innate.

As a brood parasite, the Cuckoo never learn the song of their species as a nestling. Song development is totally innate.

Sensitive phase for optimal imprinting some behavior must be

learned during a receptive time period

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Classical conditioning Ivan Pavlov’s dogs

connect reflex behavior (salivating at sight of food) to associated stimulus (ringing bell)

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Learning: Cognition Ability for nervous system to store,

perceive, and process information

tool use

problem-solving crow

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Social Behavior Some animals are largely solitary and join

with a member of the opposite sex only for mating; others pair, bond and cooperate in the raising of offspring.

Still others form a society in which members are organized in a cooperative manner.

Society— a group of individuals of the same species that cooperate in an adaptive manner; e.g. bee hive, flock of birds, wolf pack, school of fish.

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Social behaviors Interactions between individuals

develop as evolutionary adaptations Result in survival and reproductive success Agonistic behaviors Dominance hierarchy Cooperation Altruistic behavior

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Social behaviors Agonistic behaviors

Threatening & Submissive rituals symbolic, usually no harm done

ex: territoriality, competitor aggression

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Social behaviors Dominance hierarchy

social ranking within a group Pecking order

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Dominance Hierarchies A higher ranking animal has greater

access to resources than a lower ranking animal.

Decided by confrontation during which one animal gives way to another.

Once established, little or no time is wasted in fighting.

Dominant male mate more often with the females.

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Territoriality-- Protecting an area against other individuals.

Male songbirds sing to signify their territories and other males know to stay away. The song also alerts females to presence of a male.

May be adaptive—tends to reduce conflict, to control population growth, and to ensure the most efficient use of resources by spacing organisms throughout a habitat.

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Social behaviors

Pack of African dogs hunting wildebeest

cooperatively

White pelicans “herding” school of fish

Cooperation working together in coordination

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Social behaviors Altruistic behavior

Reduces individual fitness but increases fitness of others in a population

kin selection increasing survival of close relatives passes

these genes on to the next generation

How can this be of adaptive value? Belding ground squirrel

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Examples of Altruistic Behaviors In social insects such as bees, only the queen

bee and her mate reproduce.

A female chimp often mates with several males in a group because they are all related and share genes in common.

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Mating & parental behavior Genetic influences

changes in behavior at different stages of mating pair bonding competitor aggression

Environmental influences modifies behavior

quality of diet social interactions learning opportunities

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Social Behavior & Reproduction

Natural selection has favored mechanisms that promote successful reproduction.

Behavior is thus adaptive—behavioral traits can evolve.

Sexual competition among males has contributed to the evolution of large size, brilliant breeding colors, antlers, etc.

Known as sexual selection and the traits are called secondary sexual characteristics.

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Social Behavior & Reproduction Courtship rituals may be long and elaborate. May serve as a sign signal to trigger nest

building and ovulation. Male spiders offer food. Female praying mantis eats head of male

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Behavior: Nature or Nurture?

Behavior is also shaped by environmental influences (nurture).

Studies of human twins have been used to help determine to what extent behavior is inherited.

Identical twins come from a single zygote. Fraternal twins are derived from two different fertilized eggs.

Fraternal twins, even when raised together, do not have similar behaviors.

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Identical twins raised separately are sometimes very similar; for example, the German twins raised in Germany and the Caribbean both liked sweet liqueurs, stored rubber bands on their wrists, read magazines from back to front, dipped buttered toast in their coffee, and had similar personalities.

Data seems to show that about 50% in human personality traits are due to polygenic inheritance and 50% are due to environmental influences.