Animal Behaviour

Behaviour

What an animal doesHow it does it

Animals Response to the biotic Environment

Responses of animals to other animals can be intraspecific or

interspecific

They can be further classed as aggressive or co-operative

behaviours

Intraspecific Aggressive Responses

•Agonistic behaviour is aggressive behaviour towards another member of the same species involving threats, submissions, chases and physical combat. Agonistic behaviour is a contest to determine who gains access to a resource. (Does not include predatory aggression for obtaining food)

•Conflicts between members of the same species are usually resolved with ritualistic behaviour. This prevents serious injury to the combatants.

•Fighting to the death is non-adaptive to most animals. Only occurs when eliminating a stranger from another group.

•The more scarce the resource the more intense the fighting.

Aggressive behaviour

•Belligerent behaviour by an animal that threatens to harm or kill another animal with which it is competing.

•Combat is more likely to be physical if it is essential to the survival and reproductive success of the competitors.

•Natural selection favours a quick end to combat to prevent the winner from becoming too injured, to be able to take advantage of the resources won.

•Fighting between males for mates is common. Winner mates with female and passes on genes for successful fighting. Selection may cause males to become larger than females (sexual dimorphism).

Territories

•A territory is an area defended against other members of the same species.•It provides food, water supplies, nesting areas, and refuges from danger.•Ownership of a territory is signalled by vocalisations, scent marking, visual displays.•Boundary marking warns against accidental intrusion by others of its species.•Another animal is only likely to attempt to dislodge the owner of the territory if it has a chance of being successful.•Territorial behaviour is reinforced by natural selection where the benefits to the species outweigh the risks and the energy costs of defending the territory.•Territories help to regulate the population to a size that can be supported by the available resources.

Lair or Nest Territory

Home range

•Territorial behaviour varies widely. Most animals have a definite home. The area the animal covers regularly in search of food and mates is the home range. This area is not defended.

•The part of the home range defended against others of the same species is the territory.

•Aggressive behaviour is used to hold on territories.

•Adaptive Features of Territoriality

•Ensures enough space for each animal – if in short supply and needed for breeding, keeps population down.

•By spreading out reduces the spread of disease and parasites. Also harder for predators to find them.

•Most successful males hold best territories and so ensure best genes are passed on to offspring.

•Once territories are established the resources have been divided. The losers will spread out and look for food elsewhere rather than go on fighting.

•In some species males without territories do not attract mates and do not breed.

•Territories ensure enough food for the animals and their families.

•Territories ensure a safe, protected nest or home for the young or at least a place to breed in the case of communal breeding grounds.

•Animal now has an area with which it can become familiar, can learn where food, water and protection from predators is located.

•Territorial behaviour is set. Defenders and intruders know their roles.

Marking and Defending Territories

Vocalisations – e.g. birds singing on boundaries of their areas at dawn and dusk

Scent – e.g. marking with urine (dogs and cats) or faeces

Scent glands – special glands produce chemo markers. e.g.: on rump, between horns (deer), wrists (lemur), behind ears (cats)

Physical gesturing – crabs wave claws at edge of territory

Hierarchies

•Many animals that live in social groups have a dominance or social hierarchy

•It is established and maintained by agonistic behaviour.

•Once established it is maintained by ritualised displays unless a new animal enters the group or a low ranking individual challenges a higher ranking animal. Cuts down competition and tension in the group.

•Body postures are common dominance signals

•Males and females may have separate dominance systems, in monogamous systems female usually acquires mates status because he defends her from threats and attack.

•An established hierarchy reduces the number of competitive conflicts in which individuals may get injured or killed as each animal knows its position.

•Selective advantage is that higher-ranking individuals leave more offspring than lower ranked individuals , lower members have a higher chance of mating than if they were outcast.

•Gender, age and size or fighting ability are factors affecting dominance in a hierarchy.

•Position in a hierarchy is normally established early in life e.g. puppies play fighting to assert dominance.

•Wolves – female dominated hierarchy. Alpha female dominates the behaviour of those below her. Including which females are allowed to mate. Helps control the number to be fed when food is scarce and ensures survival of her own pups.

•Pukeko – both males and females have hierarchies in their communal groups.

•Barn-yard hens – linear order of dominance based on pecking order. Top bird pecks all, bird below pecks the bird below them, etc, etc. Lowest bird pecks no one.

•Strongest animal is Alpha all subordinate to them. Get best food and choice of mates.

•Dominance maintained by posture - make look bigger, standing on hind legs, fluffing up fur, holding tail erect : threat displays- slaps, bites : vocalisations – snarls

•Subordinate responds with appeasement gestures which prevent the dominant animal from attacking.

•Subordinate displays are the opposite to dominance behaviours. Include lowering head and eyes, make look smaller, cringing, tail between legs, exposing vulnerable parts

Win-Loss Tables

•Used to show hierarchies•Each interaction recorded with the winner and loser shown.•Wins shown in columns and losses in rows.•Diagonal is theoretical, monkey paired against itself. e.g.:

H E I RTotal

H 0

E 5 5

I 4 8 2 14

R 2 5 8 16

Total

Intersection of column E with row I shows that E won 8 times over I.

Intersection of column I with row E shows that never won against E.

When column I is paired with R, I wins 8 times. Whilst R wins 2 times. This is rare, as once dominance is established there are few challenges by the lower animal.

It is most likely R is a younger animal that ison the way up and is challenging I.

Intraspecific Co-operative Responses

Includes group formation, pair bond formation and parental care.Requires a form of communication:

can be visual, vocal, chemical or tactile

Group Formation – Advantages of group behaviour•Hunting - work as a team to kill prey. E.g. wolves, lions,

wild, dogs.

•Defence – form defensive circles or post guards to watch for danger whilst rest of group feeds. E.g. Himalayan yaks (circles), baboons (guards).

•Protection – Dolphins protect mothers during birth process and help carry baby to surface until it has learned to breathe. Baboons, mother and young in safest position in the pack (centre).

•Insect societies – organisms specialised to carry out aspects of maintenance of nest or hive. Centred around a queen who co-ordinates group with pheromones.

•Clumping – confuses predators, difficult to pick out individuals. E.g. shoals of fish, flocks of birds

•Breeding – Many groups from for breeding purposes. Safest breeding sites are in the centre of the group. E.g. penguins, gannets, gulls

Disadvantages of group behaviour –

•Competition for resources- abiotic and biotic•Spread of disease – closer contact of individuals•Parasites – closer contact, less likely if were spread out•Increased conflict – due to competition for resources

Courtship and Pair Bond Formation

•Animals tend to keep an individual distance from each other, even those in groups. Invading another's space is a threat.

•Courtship behaviour often shows the conflicting tendencies to attack and yet allow the closeness of mating.

•Sex is adaptive as it requires:Co-operationTemporary suppression of aggressive behaviourA system of communication, and species recognition

•Mating is not a simple process. It is fundamental to the survival of the species. Partners must make sure they are:Of the same speciesBoth fertileBoth fully prepared to mate

•Usually the female who chooses the male, male must compete for her. Two ways in which a male can gain an advantage over another male

Fighting or ritualised combatCompete indirectly in attracting females by special displays and adornments

•Sexual competition has led to evolution of such things as :

Antlers, brilliant breeding colours, feathers, ornaments.

•These make the male more attractive to the female. Male-Male dominance encounters often let the female judge the ‘fitness’ of the males.

•Some rituals allow the potential male suitors to size up the opposition without fighting.

e.g. red deer stags roar on their territory boundaries to indicate how strong they are to other males. Roaring continuously takes energy so indicates they are in good condition.

Courtship•Ensures the two animals are of the same species•May be a sign to start nest building•May trigger ovulation

•Aggression is reduced by dances, call, movements of the body in ritualised sequences, release of pheromones, or touching.

•This allows the pair bond to strengthen, so more intimate behaviours can take place.

•A pair bond is a stable relationship between animals of the opposite sex that ensures cooperative behaviour in mating and rearing of the young.

Types of Young

AtricialHelpless at birth. The young are well protected by the parents. Blackbird is a common example.

PrococialWell advanced at birth. Little care from parents. Pukeko is a good NZ example.

Parental CareSurvival species depends on the breeding population producing adequate numbers to establish a new generation.

Achieved in 2 possible strategies.

r strategy – produce many relatively unprepared young, each with a low chance of survival.

•No parental care, no investment of effort or food.•Large number of offspring produced. Chance of some will survive. •Strategy does not greatly affect health of current generation.

Parental Care

k-strategy – produce a few, well prepared offspring which have a high chance of individual survival.

•Parental care of eggs, and care of the offspring.

•Parents invest considerable effort and food reserves to increase the probability of survival.

•Young have colours and behavioural patterns that reduce aggression in parents.

•The health of the existing generation is risked to increase the chance of survival of the next generation.

•The degree of parental care varies between species.

Reproductive Strategies

•Monogamy- only 1 breeding partner. Common strategy when both parents are required to raise young.

> 90% birds are monogamous

•Polygyny – male may mate with many females, and have many young. Maximises genes passed on. Invests no parental care. Females raise young, or r strategy.

•Polygamy – dominant male may have a harem of females.

•Polyandry – mating of one female with more then one male, while each male only mates with one female. Rare <1% of birds. Male often raises the offspring

Polygynadry – promiscuity. No pair bonds, very little parental care. Males and females mate with more than one member of the opposite sex. E.g. pukekos

Synchronised spawning – species all spawn at same time.

Cooperative Breeding – mated pair builds a nest, females lays eggs in it. Hatchling cared for by parents and other members of the group.

Kin Selection – selection that favours genes that promote altruistic behaviour towards those genetically related.

Social Insects – one queen who reproduces, all others are infertile and have set jobs.

Interspecific Aggressive Responses

Competition for food

•Occurs when resources become scarce. Leads to stress and a reduction in population size, especially for the least successful species. One population may even become extinct.

•Gause’s Principle (competitive exclusion principle) – ‘no 2 species with identical ecological niches can co-exist for long in the same place’.

•One species will die out, or move away, or the species will differentiate their niches (often subtlety).

Predator – Prey

•Not truly an aggressive relationship. •Predators can limit a population to a healthy level.

•Most predators tend to catch the least well-adapted animal, sick or old.

•Keeps the gene pool of the prey strong.

•The 2 species are dependent on each others well-being.

Adaptations for getting food.Predator strategies•Pursuit strategies –

fast processing of information bigger brains,

specialised appendageshunting in swarms hunting in teams using tools

•Ambush strategies –wait and let the prey come to themsifting environment

dangling baitswebs and traps lying in ambush

•Parasitising a prey -

Parasite-Host Relations•Generally exist at expense of the host. Tend to be density dependent. Greater population numbers increase transfer rate.

•Ectoparasite – found on outside of host•Endoparasite – found inside the host

•Parasitoids – Parasitic at only one part of the life cycle. Tend to kill the host, e.g. parasitic wasps: larvae eat host but pupate into a free living adult.

Defence Strategies Against Predators

Recognise Animals by three things:

•Silhouette – an be disguised by-disruptive colouration – markings that hide body

outline-cryptic colouration – colouration matches background

•Its eye – can be disguised by-eye disappear amongst stripes, splotches-false eye in non-vital parts

•Its bulk – can be disguised by-counter-shading

Defence Strategies Against Predators

Other defences are:

•Startle the predator - fluffing up body hair or feathers to look big, flash a false eye

•Pretend to be inedible - look like a stick or faeces

•Mimicry- an organism’s close imitation of a model to which it is unrelated:

Batesian mimicry – harmless or non-poisonous species resemble one that is obnoxious or poisonous

e.g. viceroy butterfly looks like a monarch butterfly (poisonous)

•Mullerian mimicry – involves several poisonous that all have similar warning colouration.

•Aposematic Warning Colouration – an animal warns that its either dangerous or poisonous by having bright colours, especially stripes

More Defence Strategies•Warning sounds (grunts, squeaks) •firing chemicals (snakes, ants) •curling up •retreating (shelled animal) •hiding (freezing) •escape by numbers (shoals of fish, flocks of birds)•pretending to be dead •designated animal to keep watch (meercats, baboons).

Interspecific co-operative responses

•Mutualism – both animals benefit from a relationship- wrasse and some shrimp cleaning larger fish.

Cleaner gets food, bigger fish have parasites removed.

- mixed herds grazing, one warns of danger all warned

- ants and aphids, ants get honeydew and aphids get protection

•Commensalism – a relationship when one animal benefits and the other is not harmed or benefited by the arrangement

-ramora and sharks, shark makes a kill and ramora gets food

•Antibiosis relationship where one is harmed and the other is indifferent

- human waste in rivers, humans unaffected, fish harmed

- fungi producing waste products the inhibit bacterial growth