ANIMAL
BEHAVIOR
Chapters 8-10
CHAPTER 8: COMPETITION AND
TERRITORIALITY
COMPETITION AND TERRITORIALITY
 Aggressive relationships don’t only exist between predator
and prey
 Agonistic behavior– fighting and aggression that does NOT
include predator/prey relationships
 Can exist between animals of the same species, or with other species
who are not considered predators or prey
 Examples: fighting, threats, submissions, chases, territorial displays,
marking etc.
COMPETITION FOR FOOD WITHIN A SPECIES
 While animals prefer areas rich in resources, competing with others
for those same resources can require a lot of time and energy
 As the number of competitors increases, the rewards are more difficult to
obtain even if the resources are great
 Siblicide
 When siblings kill each other or hoard food from each other
 Occurs when siblings compete for resources (particularly food)
 From an evolutionary standpoint, these behaviors have evolved
because the most aggressive nestlings have survived, thereby passing
genes of aggression down to the next generation.
 https://www.youtube.com/watch?v=zPIBKrLMHUc
COMPETITION FOR FOOD WITHIN A SPECIES
 Cannibalsim/Intraspecific Predation
 Not uncommon in the animal kingdom
 To gain food and to eliminate competitors
 Examples
 “Icebox hypothesis”
 Sharks will have an extra offspring specifically for the purpose of
feeding the one that is strongest and fastest growing
 Termites eat their dead and injured
 When space is limited, guppies will eat each other
COMPETITION FOR FOOD BETWEEN SPECIES
 Competition for Resources
 Occurs between species that live in the same area and prey upon the
same animals
 Examples
 Lions vs. Hyena
 Both prey upon zebra and wildebeest
 Competitive Exclusion
 When 2 species compete for limited resources, eventually the more fit
species excludes or eliminates the competitor when they occur together
 Forces the less competitive species to inhabit the less preferred habitat
COMPETITION FOR FOOD BETWEEN SPECIES
 Competitive Exclusion cont.
 Closely related species eating near each other
 They fill a different niche in their environment
 Examples
 Warblers, marmosets and tamarins
 The golden-headed lion tamarin forages in the upper levels of the
forest and Kuhli’s marmoset forages in the middle and lower levels
of the forest
COMPETITION FOR MATES
 Aggression can help an animal achieve reproductive
success in 4 ways
1.
Helping the individual obtain a mate
2.
Guarding against a mate having sex with other individuals
3.
Increasing the individual’s chance for fertilization
4.
Reducing the offspring’s competition
COMPETITION FOR MATES
 Assessment
 Process animals use to determine if the animal they are to fight is too big
or too small to worry about
 Can be a long process of vocalization, strutting and actual fighting—3 steps
 Ritualized behavior– when dominance is established without actual fighting
 Saves injuries and lives
 Rutting– when two animals of equal stature decide to fight
 Necking in giraffes
 https://www.youtube.com/watch?v=C7HCIGFdBt8
 Deer
 http://www.arkive.org/fallow-deer/dama-dama/video-12a.html
COMPETITION FOR MATES: COSTS AND BENEFITS
 Costs
 Injury or death
 Benefits
 Reproduction
 Factors in determining who mates with females
 Age
 Older, weaker lions give way to others
 Size
 Smaller and weaker give way to larger and stronger
 Who gets there first
TERRITORIALITY
 Territory
 An area an animal will defend
 Home range
 Usually covers the territory as well as a larger area that the animal uses to
look for food and mates
 Core area
 Within the home range and territory
 Den/nest and immediate surroundings where they spend most of their time
 Conspecifics
 Members of the same species competing for territory
WHAT DEFINES TERRITORIAL BEHAVIOR?
Defensive behavior is confined to the territory
2. The defended area is used exclusively by the resident defender
unless it is deposed by a newcomer
3. Defense involves agonistic behavior such as warnings, threats,
displays and sometimes aggression
4. When an animal intrudes into another’s territory, the intruder
behaves submissively toward the resident and not all intruders
into the animal’s territory are attacked. Neighbors are
recognized and considered ok, new conspecifics would be
attacked
1.
WHO WINS TERRITORIAL DISPUTES?
 2 main factors
1.
When equally matched, resident will usually win a dispute and keep their
territory
2.
When NOT equally matched, generally size wins the dispute
 Evolution has shown that average reproductive success should
increase with habitat quality and should decrease as the number
of competitors increases
 Examples:
 Impalas
 Toque Macaque
 Emporer scorpion
ESTABLISHING BOUNDARIES
 Scent Marking
 Using pheromones to mark territory to prevent fighting
 Done with urine, feces, or scent glands
 Gets animals to turn around and leave an area
 Mostly done by mammals (Birds never do this)
 Example:
 Spotted hyena
 Urinate and defecate in special areas at the boundaries of their territory
called latrines, then smear it around with their paws. The feces turn white,
making the outline of the territory very obvious to those nearby
 Pasting– done by hyenas along their hunting trails
 have anal glands that secrete a white smelly substance to mark territory
ESTABLISHING BOUNDARIES
 Vocalization
 Use of loud calls to mark territory
 Scratching trees
 Visual display to other animals to mark territory
 Aggressive displays
 Use gestures, body displays, actions, appearance of increase in size, bare teeth to
mark territory
EVOLUTIONARILY STABLE STRATEGIES
 Way of behaving that gradually becomes the typical
pattern of behavior in a population over time
 Submissive displays
 Communicating to the aggressor or resident that the animal will not compete for
resources
 Example:
 Puppies rolling onto their backs and displaying their stomach is a submissive
display
 Wolves and large dogs will lay down and flatten their ears to show they will
not compete for resources
EVOLUTIONARILY STABLE STRATEGIES
 Mixed Strategy
 Capable of changing it up depending on the circumstances, can be dominant or
submissive depending on who is in the particular area
 Bourgeois Strategy
 Be dominant in your territory but submissive in someone else’s territory
CHAPTER 9: COMMUNICATION AND
LIVING IN GROUPS
COMMUNICATION
 Process in which one individual sends a signal to
other individuals and in turn the receiver responds
to the original signal in some way
 The sender and receiver are usually, but not always,
conspecifics
 The signal is usually advantageous to the sender
 Example– Crickets chirp in order to attract a mate, but that same chirp
may tip off a predator that prey is nearby
CHANNELS OF COMMUNICATION
 Most familiar way to communicate
 Sound, visual displays and touch
 Modern humans use mostly their hearing and vision to
communicate
 The signal is usually advantageous to the sender
 Example– Crickets chirp in order to attract a mate, but that same chirp may tip off a
predator that prey is nearby
 Chemical trails are used in lots of other mammals and insects
 Scent marking
CHANNELS OF COMMUNICATION
 Less common forms of communication include electric
fields and substrate vibrations
 Examples: fish using self generated electric fields and spiders using web
vibrations
 Mode of communication depends on the needs and
demands of the animal
 Example: small nocturnal mammals are more likely to use sounds and scents
to communicate rather than visual displays
SOUND
 Acoustic signals are usually produced by a few methods
 Expelling air over a membrane
 Forcing air through a resonance tube
 Rubbing body parts together
 Benefits
 Can radiate in all directions and even around objects
 Can be turned on and off
 Costs
 Require a lot of energy
 Can be overheard by predators
SOUND
 Mammals and lots of birds use sound to indicate nearby predators
 Variation in the call can indicate what kind of predator it is
 Calls
 Short and simple vocalizations
 The most complex signals are used by vertebrates
 Songs
 Whales etc
 Humpback whales can sing songs that last 22 hours
 Most complex
 Humans
VISUAL MESSAGES
 Displays
 Pattern is adapted in physical form or frequency to function as a social signal
 Many have evolved into a pattern of behavior that are very stereotyped and constant
 Outcome is easily and immediately identifiable by receiver
 Benefits
 Transmitted quickly, convey a lot of information and highly directional
 Little cost of energy if done by displaying parts of their own body (the peacock
below)
 Disadvantages
 Can be blocked by objects
 Cannot be seen over a distance
 Not useful at night
VISUAL DISPLAYS
 Some displays come from light that the animal is capable of
producing
 Example: Firefly, flashligh fish, firefly squid, etc.
 http://www.youtube.com/watch?v=Jk_EmI4te20
 http://www.arkive.org/firefly-squid/watasenia-scintillans/video-00.html
TOUCH
 Very limited—animals need to be in close proximity for physical
contact to occur
 3 important functions across species
1.
Grooming communication
 Shows dominance and submission thereby cement social relationships within the
group
2.
Initiate giving of food to the individual who sent the message
 Offspring send a message to parents, therefore parents go get and take food to
offspring
3.
Initiate transport on another animal
 Ants will tug on or bite the mandible of another ant telling them that they want
a ride
CHEMICAL PATHWAYS
 Pheromones—most universal mode of communication
 Less flexible method than sound
 Advantages
 Cheaper to produce
 Less risky (can be picked up by members of its
species only
 Can last a long time
 2 classifications of chemical messengers
1. Releasers
 Pheromones released in order to affect the behavior of another (Ex: scent
marking your territory)
2. Primers
 Affect another’s physiology (Ex: mouse urine from male aborts fetuses in females
he didn’t impregnate
FUNCTIONS OF COMMUNICATIONS
 Ritualization
 Behavior that provides information to another animal will become habitual,
stereotyped, or “ritualized”, if it leads to that animal’s responding in ways that are
advantageous to the animal exhibiting the ritualized behavior
 Example– Herring gull chicks peck at a red spot on the parent’s beak to get them to
regurgitate food for them. Both the pecking and regurgitating are considered
ritualized behaviors.
RECOGNITION FUNCTIONS
 Kin Recognition
 Being able to recognize members of the same species, population, or family
 Example– chemical markings in bees, ants etc.
 The entire colony is infused with a colony specific chemical odor provided by the
queen. Any animal that does not possess this is treated as an enemy.
 Mate Recognition
 Being able to recognize your mate through vocal cues or differences in
characteristics
 Example– Emperor penguins returning from the sea or primates recognizing
distinctive facial characteristics
GROUP COORDINATION
 Social calls in groups such as: dolphin family, seals, birds, primates
and humans
 Example
 Orcas
 Many live in territorial groups called pods.
 Each pod uses its own dialect to communicate with one another, similar to how
humans (one species) communicate using a variety of different languages.
ALARM AND HUNTING/FORAGING
 Alarm
 Signals to warn each other of danger
 Can be used to alarm conspecifics or members of a different species
 Alarms are most often communicated through vocal or chemical means
 Hunting/Foraging
 Effective communication in group hunting equals more effective hunting
 Can make it easier for the group to catch larger prey
 Communication is most often made through vocal or chemical means
http://www.bbc.co.uk/nature/life/Meerkat#p00f3h6l
GROUP LIVING
 Aggregations
 Group of animals such as herds, flocks or schools
 Stay and move together as a defense mechanism
 While they stay and move together, the group does NOT have a definite structure,
organization or communicate with one another
 Organized society
 Division of labor, communication with group, resistance by the group to outsiders
 Dominance relationships
 Example– humans, other primates, wolves, lions, wild dogs
 Eusociality
 Special organized society
 Most members of the group are sterile and cannot reproduce
 Caste system– perform certain tasks based on treatment early in development
 Example– insects, such as ants, termites, some bees, naked mole rats
DOMINANCE
 Birds
 Dominance hierarchy may be indicated by variations in their plumage or color rather
than their behavior– “Badges of Status”
 Example– Scarlet tufted malachite sunbirds
 Those that have more red on their chest are more dominant and have a larger
territory
 This is true for some bird species but not all
 Mammals
 Dominance is determined by a variety of things
 Size, testosterone level, aggression, weapons, alphas, inherited from parent etc.
ADVANTAGES OF ANIMAL DOMINANCE
1. It provides stability in the population
2. Destructive aggression is minimized because animals are only
rarely killed or seriously harmed in dominance contests, and
once dominance relationships are settled, peace tends to reign.
3. Fitness is increased
4. The population spreads itself out in the environment
ECOLOGICAL FACTORS IN GROUP LIVING
 Most animal species throughout the world live on their own, so
why do some live in groups??...
 Costs
1.
2.
3.
4.
5.
Increased competition
 For mates, nest sites, food and water
Increased exposure to disease and parasites
 More susceptible to domestic animal disease
Interference with reproduction and parenting
 Too many babies or disturbed by other animals
Increased conspicuousness
 Make a lot more noise, take up more room and take up more space
Overcrowding
 Causes aggression, anxiety and unusual behaviors
ECOLOGICAL FACTORS IN GROUP LIVING
 Benefits
1.
Increased vigilance
 Can spot predators sooner which provides better protection for individuals
2.
Dilution
 Less chance of getting grabbed by a predator
3.
Cover
 Those at center of group do better
4.
Group defense
 Confusion effect– predator put off by commotion of the group
 Mobbing
5.
Group attack or group hunting
ECOLOGICAL FACTORS IN GROUP LIVING
 Benefits
6.
Exchange of information
7.
Warmth
8.
Mating swarms
 Easier to find mates
9.
Division of labor
10. Richer learning environment
 Provides more behavioral models, feedback and stimulation for curious
young.
 Mammals mostly, especially primates
SEXUAL CONFLICT, SELECTION AND
COURTSHIP
SEXUAL CONFLICT
 In order to maximize reproductive success, males and
females develop and behave differently
 Reproductive success= offspring surviving to birth
 Females (usually): makes sure the egg makes it to birth and survives
 Only way to ensure reproductive success is to see that offspring grow
and reach adulthood
 Males (usually): fertilize as many eggs as possible
 Because of female/maternal behaviors males are driven to compete for
females.
 This causes males to be bigger and more aggressive than females
and give them more energy to obtain mates instead of
characteristics suited for parental care of offspring
SEXUAL SELECTION
 Sexual dimorphism
 When males and females look and behave differently
 Greatest in species where males compete hardest for females
 Can be color, size, etc.
 Sexual selection
 Males and females evolve different bodies and behaviors to maximize
their individual reproductive potential
 Generally takes 1 of 2 forms
 Intrasexual selection
 One sex competes vigorously to acquire the right to mate with the
other sex
 Intersexual selection
 One sex (usually the female) chooses which individual to mate with.
Competition between males is still there, but just for attention and
acceptance of the females
INTRASEXUAL SELECTION
 Males will try and hoard or guard a large group of females
 Females ready to mate are said to be in estrus
 When multiple females are in estrus at the same time they are said to be in
synchrony
 Males will corral the females when they are in synchrony and will be
solitary the rest of the year
FORMS OF INTRASEXUAL SELECTION
 Being sneaky
 Female mimicry– smaller males will pretend to be females and as a result
will be able to mate frequently with females in a group without the
dominant male knowing
 Example: Bluegill
 Satellites– Sit by the dominant male and try to steal females before he can
get them
 Example: Bullfrogs
 These “sneaky strategies” do not work as well as the main
strategies for mating but they do obtain some reproductive
success
FORMS OF INTRASEXUAL SELECTION
 Guarding and Repelling
 To prevent other males from mating with that female after they did
 By staying with or on the female, or by leaving an odor on her to repel other
males
 Examples: insects and worms do this a lot
 Sperm Competition
 Some insects can remove other insect’s sperm before fertilizing the female
 Example: Damselflies
 Some animals can prevent others from mating with the female by inserting a
“sperm plug”
 Example: insects and marsupials
 Murdering other male’s offspring
 Example: Lions
FORMS OF INTRASEXUAL SELECTION
 Dual Male Forms
 Males develop 2 different phenotypes, both which work equally well for
reproduction
 Example: Coho salmon
INTERSEXUAL SELECTION
 Competition is more related to sounds or visual displays
 Better display = better genes
 Females are choosy and take their time finding the right mate
 Some species depend on who is the best provider to the young by giving
food to the female
 Example– birds and insects
 Trivers’ Theory of parental investment
 Whichever sex invests more energy, time and resources gets to be the
chooser
INTERSEXUAL SELECTION
 Courtship Rituals
 Usually performed by male and female
 Steps
1.
2.
3.
4.
5.
Identification– make sure it is the correct species
Reduction of aggression– do something to prevent getting eaten
instead of mating
 Example: giving gifts, soothing mate, tying mate down, etc.
Fitness assessment– to see how healthy and ready a mate is by their
display and behavior
Mating readiness assessment– to make sure that both are
physiologically ready to mate
Bonding– in species that bond for life and/or raise the young together,
this time is needed to do that properly
INTERSEXUAL SELECTION
 Courtship Display
 Usually performed by one sex
 Runaway evolution theory– trait being selected for that continues to
grow and might get too exaggerated or big and become a problem or
hindrance for the animal
 Example: Male peacock tail
 Good genes theory– that only the healthy males would have the full and
long feathers so they are more desirable
 Lek display– when a group of males with no resources, no nest, and no
parenting to the offspring will do colorful dances to get the female. The
female then chooses the vest one
 https://www.youtube.com/watch?v=x7FKMAgS1mU
ALTERNATIVE REPRODUCTIVE STRATEGIES
 Hermaphroditism
 Species tat possess both male and female reproductive organs and can
exchange both sperm and egg cells
 Example– sea slugs, earthworms, snails
 Self fertilization can happen but is rare
 Allows them to produce offspring since they don’t encounter others often
ALTERNATIVE REPRODUCTIVE STRATEGIES
 Sex change as a reproductive strategy
 Why can this happen?
 These animals have external fertilization, so it is easy to switch from
one sex to another
 Protogynous hermaphroditism
 Switch from one sex to the other sex
 Example– blue headed wrasse are born as females but then switch to
males as they get larger
 Protandrous hermaphroditism
 When one sex switches sexes due to the size of their new mate
 Example– clownfish will change sex so that the larger of the two is
always the female