Chapter 49Animal Behavior

Animal BehaviorEthology—study of animal behavior as a

branch of biology. Tends to look at animals in natural environment.

Comparative psychology—study of animal behavior as a branch of psychology. Tends to look at animals in experimental situations.

Behavioral ecology—study of the ecological and evolutionary basis for animal behavior

Animal BehaviorMostly studied beginning in early 20th

centuryPioneers

Ivan Pavlov—association behaviors, conditioned reflex. Won Nobel Prize in 1904.

Niko Tinbergen—Individual & social behavior patterns

Konrad Lorenz—Instinctive behavior, imprinting

Karl von Frisch—Communication & pheromones in bees

Tinbergen, Lorenz, von Frisch won Nobel Prize in 1973 for their behavioral work

Adaptive SuccessBehaviors help promote

individual’s production of offspring

Give benefit to survivalFood gatheringPredator protectionMate selectionYoung rearingResource useTerritory protection

Behavioral QuestionsFirst described by Niko TinbergenWhen analyzing behavior, ask the following questions:

Function—how does the behavior impact on the animal's chances of survival and reproduction?

Causation—what are the stimuli that elicit the response, and how has it been modified by recent learning?

Development—how does the behavior change with age, and what early experiences are necessary for the behavior to be shown?

Evolutionary history—how does the behavior compare with similar behavior in related species, and how might it have arisen through the process of phylogeny?

Instinctive BehaviorsNervous system “pre-wired”

before birth/hatchingBehaviors do not need trainingGarter snakes & slug

preferenceCoastal snakes eat slugsInland snakes ignore slugsHybrids intermediate

Garter snakes & strikingCaptive-born snakes will strike

at model with bird eyes

Instinctive BehaviorsFruit flies & mating gene

Males must perform behavior or females won’t mate

Gene can be turned of in males and turned on in females

Hormonal influences—voles & matingFemales with high oxytocin

levels (due to mating or injections) mate for life

Females with oxytocin blocked do not bond

Instinctive BehaviorsFixed action pattern

Behavior or sequence of behaviorsInstinctualFollowed to completion once startedNot always completely “fixed”, can be

modifiedFirst described by Tinbergen &

LorenzSign stimulus—outside stimulus that

triggers FAPGraylag goose

Will roll a displaced egg back into nest Will roll ANY egg-like object back into nest

Many mating displaysChick begging

Parent landing at nest Red spot on beak

Learned BehaviorsEnvironment & experiences

influence gene expression (behavioral)

BirdsongInstinctual behaviorVariations, dialects exist in

different habitatsBirds learn pattern in first

few weeks of life

Learned BehaviorsMacaques—Imo

Learned to wash potatoes in sea

Learned to wash wheat by throwing into sea

Others performed same behaviors by observing

Chimpanzees—tool useVaries by regionSticks for gathering termitesRocks for opening nuts

Learned BehaviorsMany behaviors related to

timingErik Erikson’s 8 stages of

development As child ages, behaviors develop

at different times Birth-18 mo, basic trust 6-12 yr, self-confidence or

inadequacy among peersDogs

Accept new experiences between 4-12 weeks old

After 14 weeks old, more fearful of new things

Learned BehaviorsImprinting

Learning occurs at a particular stage in life

Filial imprinting Lorenz Many birds will “imprint” on

moving object in 1st 36 hours of life.

Consider that object their parent Can be useful in rehabilitation

Sexual imprinting Learn characteristics of desirable

mate Zebra finches prefer mates that

appear like bird that reared them.

Learned BehaviorsAssociation

Stimulus linked to another stimulus that may not be related to the first

Pavlov Ring bell before feeding dogs Dogs salivated Eventually salivated just with

bellFish moving to surface

when hand seenDog excited when seeing

leash

CommunicationInstinctive & learnedSent & received among a speciesSignals—single cue, meant to change

receiver’s behaviorDisplays—pattern of behavior, social signal

Communication SignalsPheromones

Signaling—induce receiver to respond fast Honeybee alarm calls Sexual attraction

Priming—induce physiological change Urine of male mice can induce

& enhance estrus of females

Communication SignalsAcoustical

SoundsAttract females (birds,

frogs)Alarms (prairie dogs)Territory possession

(wolves, birds, kangaroo rats)

VisualVisible changes in

behavior or appearanceLaid-back vs. erect earsErect hairsColor changes

Communication DisplaysMore complicated than a

signal, sequence or pattern of behaviors

CourtshipWell developed in birds,

mammals“Dance”Often elaborate patterns,

ritualized stepsNormal movements or

structures exaggerated or frozen

Communication DisplaysThreat

Signaler prepared to attack receiver

Signaler benefits if rival backs down without fight

Receiver benefits by avoiding serious injury or death

ProtectionTerritoryMates

Communication DisplaysInformation

Many insectsVon Frisch & bees

When return to hive, move in specific patterns

Pattern tells others distance & direction of food

Sexual SelectionCompetition for

reproductionUsually female choosing

among malesDifferent than courtship

displays, but may include them

Nuptial gift—male brings female food item, female chooses male with best one Many insects, flies,

spiders

Sexual SelectionLek

Mating arenaMales gather in single area

& display or competeFemale moves among them

& choosesGenerally compete for center

positionDeer, some fish, many birds

Physical competition between males

Extravagant physical displays (peacocks)

Parental CareCare of young requires time &

energyCould use this for survival &

more reproductionYoung more likely to survive w/

careCost of care usually outweighed

by survival improvementNumber of offspring decreases as

length of parental care increasesThe more involved the male is

with care, the more monogamy seen

Parental CareNo Care

Neither parent gives any interest after laying eggsMost invertebrates, most vertebrates except birds &

mammalsPaternal Care

Father cares for youngRare (seahorses, midwife toads, some birds & mammals)

Maternal CareMother cares for youngMost common if any parental care

Bi-Parental CareBoth parents care for youngMost birds, some fish, many mammals

Parental CareInfanticide

Killing of youngMost often by unrelated

males Eliminates rival males’

genes May stimulate female to go

into estrus, enabling him to breed

Rats, lions, many other animals (especially mammals)

Some females spontaneously abort when new male takes over

Social BehaviorIn most habitats, costs

outweigh benefitsCompetition for limited

resourcesLarge social groups

attract more predatorsCrowded conditions

encourage spread of parasites & disease

Animals of the group more likely to be injured, killed, or exploited by others

Social BehaviorCooperative predator avoidance

Some species have sentinels that give alarms Meerkats, prairie dogs, vervet

monkeysSome join in counterattack

Smaller birds mob predatory birds Ants, bees mob when nest disturbed

Some have more effective defense Sawfly caterpillars “Selfish Herd”—protect collective

self-interest, protect young

Social BehaviorCooperative hunting

Larger prey than could be killed individually

Prey that could otherwise fight or outrun predator

Two or more individualsMany animals of all kinds

Wolves, lions, wild dogs, starlings, orcas, tuna, army ants

Reproductive advantageEasier access to mates

Communal care of youngAnts, bees, rats, primatesCost of care distributed among

adults

Social BehaviorDominance Hierarchies

Uneven distribution of resources

Dominant gain more resources

Subordinates might not survive on own

Subordinates might live long enough to reproduce

Social BehaviorEusocial animals

“True social”—highest level of hierarchy division

Distinct social classes/castes

Division of laborBreeding female dominates,

others don’t breedRemain together for many

generationsInsects (wasps, bees, ants,

termites)Mole rats

Social BehaviorEusocial animals (cont.)

Altruistic behavior—helps others, harms or gives no benefit to performer Australian honeypot ant

worker—living container Soldier termite—bombards,

nozzle headGenes not passed, but can

be favored if closest relative will benefit

2 siblings as genetically identical as parent & offspring