1. Innate behaviors are hardwired and occur without learning. They are performed through fixed action patterns (FAPs) triggered by sign stimuli. 2. FAPs are species-specific sequences of behaviors that are released and completed once started. Examples include nest building, courtship dances, and aggression displays. 3. Sign stimuli are simple cues that trigger FAPs. Exaggerated sign stimuli called supernormal stimuli can elicit exaggerated responses. Brood parasites use supernormal eggs/chicks to elicit more care from hosts.

1. Concepts of Ethology And types of behavior
Fixed Action Pattern, Sign stimulus, Action Specific
Energy and Innate Releasing Mechanism
DR RENU KOHLI
Department of ZOOLOGY
GOVT BANGUR COLLEGE
PALI

2. Innate Behaviour and Concept of Fixed Action
Pattern(FAP)
 Innate behaviour are the behaviour that are inherent and occur naturally
,that is they are the behavior you are born with, and passed from generation
to generation through genes ie the behaviour that are hardwired in neural
network in an organism.
 they are also called instinctive behavior . They can be performed without
prior experience meaning that animal raised even in isolation will perform
the behaviour.
 They are species specific
 Innate behaviour occur virtually in all species of animals but generally in
species having short life span,a greater proportion of behaviour are innate.

3.  Innate behaviour is performed in a sequence of action,
so called Fixed Action Pattern
 FAP/Innate behavior are rigid and stereotyped ,that
they are performed in the same way and maintain its
characterstic rigidity.
 Evoked or released by a stimulus, but not guided nor
controlled by that stimulus. The behavior is
endogenous, and it is released and once started it goes
to completion

4. Examples
 Nest building in birds e.g Baya weaver are best known for
elaborately woven nest. The weaver bird builds the nest without
prior training.
 Wing cleaning in birds and in some insects
 Songs of cricket and birds
Swimming in fishes and other aquatic species
 Elaborate courtship behaviour such as mating dance in bird, such as
peacock ,which often consist of a specific sequence of ritulized
movement The peacock starts dancing to attract peahen they do
not learn dancing by watching conspecific .d. Insects such as
jumping spider are famous for their ballroom skills.
 Honey bee communication by dance to share information about the
direction and distance of food etc are some examples of innate
behaviour.

5. Some classic examples of FAP
Egg rolling of Greylag goose
 A well studied example of FAP is of the greylag geese a ground
nesting bird , if the egg rolls out of nest,the female instinctively
push the egg back to nest with her bill and neck with repeated
specific action. The sight of egg outside the nest is the stimulus
that trigger the retrieval behavior.
Male Stickleback Fishes Aggression
 Niko Tinbergen in 1952, also studied a species of fish commonly
called the red-bellied stickleback. The male of this species
changes color ,turns bright red bellied during breeding season
establish a territory and thus naturally aggressive towards other
red-bellied male stickleback.

6.  The red belly acts as sign stimulus that releases aggression in male
stickleback. Niko Tinbergen used crude models to study eliciting of
the courtship and attack behaviour from male sticklebacks . He
found that attack behaviour occurs when red bellied male
stickleback fish was presented with unrealistic models with red belly.
They do not attack o realistic model that look like fish but lacks red
underside.
 These two examples show:
 i )FAP show highly rigid and stereotyped ie the behavior is invariable
 ii) FAP need sign stimulus for release
 iii) FAP are non modifiable through learning

8. 1.KASPER HAUSER
 An experiment in which an animal is reared in isolation from members of its own species .
Chaffinches are the songbirds ,the male chaffinch has a strong voice and they have loud songs
and varied calls. The male can learn song pattern during the first 13 months of life, if it is reared in
auditory isolation ,chaffinch cannot sing normally ,it sings extremely simple song of low intensity
and not as melodious as wild chaffinches .The song of casper hauser though has right length and
right number of song. Full song of chaffinches is thus integration of innate and learned behavior
and they learn some features of the song from their male parent during first few week of life .
 Grey squirrel frequently bury the nuts ,some squirrel were reared in isolation and were never
given nuts,,but when such squirrel were given nuts they ate then and attempted to bury nuts in
the ground , typically like all other squirrel. Thus the behavior of squirrel is innate and show a
Fixed Action Pattern.
2.In Vacuo
 This term in 1930 was given by Konrad lorenz, according to him when animal perform FAP it
seems that he is releasing some kind of tension .
 In after a long period of absence of an appropriate releaser the animal may perform a fixed
action pattern without a stimulus. (In vauo release)
 A weaver bird in breeding season deprived of nesting material has been seen to go through
complicated nest building behaviour .Such a release of FAP is called in Vacuo.

9. Concept of Sign stimulus
 Sign stimuli also called releasers are simple, conspicuous and
specific stimuli that are capable of releasing Fixed Action Pattern or
Consummatory behaviour in animal . Bright coloured plumage of
male of many species of birds during courtship is sigh stimulus for
attracting female.
 Birds chicks respond to the jerk in the nest ,which is sign stimulus for
them to open their beak for eating food.
 Herring gull has a red spot on its beak , when chicks peck at the spot
,the pecking act as sign stimulus and triggers a response to
regurgitate food. Red spot on herring gull’s bill .The territorial fighting
in male robin is triggered by sign stimulus of red breast, even a bunch
of red feathers can induce territorial behaviour
 Sign stimulus is often not one but a combination of many stimuli like
shape of bill , colour of body or action or auditory signals.

10. Supernormal stimuli
 Exaggerated sign stimuli can lead to exaggerated response ,these
kind of stimuli are called supernormal stimuli .A supernormal
stimulus is defined “as a stimulus that elicits a response stronger
than the stimulus for which response mechanism evolved.”
 In a famous set of studies done by Niko Tinbergen in 1950 where
he created super normal stimuli of beak and heads of gull ,he
found herring gull pecked more at big red and longer object than at
adult herring gull beaks.
 Human too are sensitive to modern supernormal stimuli some
examples are preferences for processed food , movie
superheroes, television shows and video games and social media
among others . A wide range of product are marketed by
advertising agencies by tapping into supernormal response.

11. Brood Parasitism and supernormal stimuli
 Brood parasitic birds lay their eggs in the nest of others
.Cuckoo’s lay their eggs in certain other bird species to be
incubated by the foster parents , who rear the young cuckoo.
 The cuckoo’s egg resemble those of host but it is often bit
larger or brighter, the host sit on the cuckoo eggs
preferentially, when the baby cuckoo comes out of egg its
beak is wider and has enormous and glossier gape than the
other chick .The foster mother give more attention than her
own hatchlings.

12. House crow feeding Asian koel

13. Grey lag goose when presented with egg models
that are more conspicuous or larger than their own
eggs , retrieve those exaggerated forms into the
nest. Grey lag goose

14. Concept of Innate releasing mechanism (IRM)
 Innate releasing mechanism is a hypothetical neurological
mechanism that exist in an animal that respond to stimulus and
triggers preprogrammed stereotyped behavior or fixed action
pattern in an animal. Lorenz used the term “Angeborener
Auslosmechanismus” later Tinbergen changed the term into
Angeborener Auslos-Mechanismus (AAM)meaning IRM =innate
releasing mechanism
 For each FAP there is a separate IRM ,which is like a ‘gate’ to
reservoir of energy that releases the FAP in response to a
specific sign stimulus

15. ACTION SPECIFIC ENERGY
 Action Specific Energy : Action specific energy also known as specific
action potential [SAP] . It’s a hypothetical supply of Energy associated
with every fixed action pattern
 Konrad Lorenz postulated that action specific energy or energy for a
specific action is constantly being produced, in the animals central
nervous system.
 The action specific energy is that energy which is required for carrying
out a particular fixed action pattern and It is being produced
continuously in an animal's central nervous system , but it is held in
check by some inhibitory mechanism until the appropriate sign stimulus
releases this energy and subsequently fixed action pattern. Each fixed
action pattern is thought to have it's own action specific energy.
 On receiving appropriate sign stimulus through sense organ and it is
sent to the hypothesized locus innate releasing mechanism in central
nervous system , which releases action specific energy to elicit fixed
action pattern.

16. Psycho-hydraulic model or flush toilet model of
Lorenz(correlation between SS,IRM, ASE and FAP
 The term proposed, by Lorenz, refers to a model that is
comparable to hydraulic flow system such as a flush toilet, explain
correlation between sign stimulus , innate releasing
mechanism, action specific energy, and fixed action pattern.
 The fluid in the tank is analogous to action–specific
energy(ASE)which accumulated over a period of time, increasing
the animal’s drive to perform a particular period.
 Sign stimulus (weight)acts on IRM (spring and valve)which in turn
allows FAP to flow from reservoir to carry out FAP.
 An important feature of the model is that after the animal has
engaged in a particular behaviour (FAP) there is a period of time
when they less likely to respond even if the same stimulus is
presented again during behavioral quiescence.

17. Psycho – hydraulic model

19. Thank you