Summary
Stereotyped behaviours triggered by a sign stimulus and carried through to completion, like the stickleback's attack on a red belly.
In depth
Triggered by sign stimuli, e.g. red spot on gull's beak triggers chick pecking, and red belly triggers male stickleback aggression. Supernormal stimuli exaggerate the trigger; birds prefer larger artificial eggs.
Fixed action patterns, once started, run to completion even if the stimulus vanishes. The neural command is believed to be a stored motor program. They are species-typical, making them useful characters for classifying species.
Remember: they differ from reflexes by being more complex and requiring motivation.
A fixed action pattern (FAP) is a stereotyped sequence of movements triggered by a sign stimulus and then performed to completion even if the stimulus disappears. Tinbergen showed that male sticklebacks attack crude models with a red underside but ignore accurate models without it.
The sign stimulus is processed by an innate releasing mechanism in the nervous system, which is why supernormal stimuli, such as an oversized artificial egg, can be even more effective than natural ones. Greylag geese retrieving a displaced egg continue the motion even when the egg is removed.
Example: a cuckoo chick's gaping mouth triggers feeding by the host parent.
Key idea: FAPs are simple but may be exploited by mimics.
Frequently asked questions
What is Fixed Action Patterns?
Stereotyped behaviours triggered by a sign stimulus and carried through to completion, like the stickleback's attack on a red belly.
Which area of biology covers Fixed Action Patterns, and how advanced is it?
Fixed Action Patterns is one of the 53 topics in Animal Behaviour. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Instinct, Innate Behaviour, Courtship.
Can you give an example of Fixed Action Patterns?
Once started, egg-rolling in greylag geese continues even if the egg is removed.
What should I learn before Fixed Action Patterns?
Work through the Beginner topics in Animal Behaviour first, such as Animal Behaviour, Innate Behaviour, Learned Behaviour, then return to Fixed Action Patterns. Intermediate topics assume the Beginner vocabulary.
What topics are related to Fixed Action Patterns?
The closest topics to Fixed Action Patterns are Instinct, Innate Behaviour, Courtship, Imprinting. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Fixed Action Patterns?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Fixed Action Patterns. To practise the whole of Animal Behaviour, use the Animal Behaviour quiz.
How is Fixed Action Patterns different from Instinct?
Fixed Action Patterns: Stereotyped behaviours triggered by a sign stimulus and carried through to completion, like the stickleback's attack on a red belly. Instinct: An inborn pattern of behaviour triggered by a particular stimulus. Read both side by side and note what each one explains.
How should I study Fixed Action Patterns step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Instinct and explain the difference aloud. Finally, take the Animal Behaviour quiz and come back to this page for any question you miss.