48 Intraspecific Communication

Key Idea: Communication is the transmission of (understood) information between individuals, usually of the same species. It is essential to species survival and reproductive success. Effective communication enables animals to avoid predators, coordinate foraging and hunting activity, maintain social behaviours, and attract mates. Messages can be passed between animals using a range of signals that may be visual, chemical, auditory, or tactile. The type of signal used depends on the activity pattern and habitat of the animal, e.g. sound carries well in dense forest.

Code Channel The medium in which the signal is transmitted: visual, chemical/olfactory, tactile or auditory Signal

The message conveyed from one individual to another: Aggression, submission, courting, social bonding

Code

Sender The individual who transmits the signal

Rules by which the sender must transmit the signal

The two male baboons on the right are engaged in a dominance display. Both animals are acting as senders and receivers of a message. Rules that enable the receiver to decipher the signal

Receiver The individual who detects the signal

Context

The setting in which the communication occurs: dominance display, courtship, predator alert, food gathering

Fixed action patterns and communication

The correct transmission of some messages is so critical that the method of transmission has become genetically fixed and the behaviour cannot be altered by learning or external stimuli. This kind of behaviour is called a fixed-action pattern (FAP). FAPs are spontaneous, stereotyped (always the same), and indivisible. Once begun, a FAP runs to completion and is independent of learning. Many FAPs have been identified in animals. The one illustrated below relates to feeding the southern black-backed gull (Larus dominicanus). Similar behaviour occurs in many other gull species.

Brian Gratwicke

Releaser or sign stimulus

Innate releasing mechanism FAP

The red dot on the bill of the adult gull acts as a releaser for a fixed action pattern in the chick (the chick pecks at the red dot). The pecking action acts as a releaser for a fixed action pattern in the adult, in which it regurgitates food (above). The behavioural response to the sign stimulus is mediated via a neural processing system called the innate releasing mechanism. The message "I'm hungry, feed me" is therefore communicated in a unchanging way, which is recognised by both parties.

1. Why do animals need effective communication over both long and short distances?

2. (a) Explain the role of releasers in behaviours involving fixed action patterns:

(b) Name a releaser for a fixed action pattern in gulls and describe the behaviour elicited:

Olfactory messages

Some animals produce scents that are carried by the wind. Scents may advertise for a mate or warn neighbouring competitors to keep out of a territory. In some cases, mammals use their urine and faeces to mark territorial boundaries. Sniffing genitals is common among mammals.

RA

Tactile messages

Touch may be part of a cooperative or an aggressive interaction. Grooming behaviour between members of a primate group communicates social bonding. Vibrations sent along a web by a male spider signal to a potential mate not to eat him.

Auditory messages

Sound may be used to communicate over great distances. Birds keep rivals away and advertise for mates with song. Fin whales send messages over thousands of kilometres of ocean. Calls by mammals may attract mates, keep in touch with group members or warn away competitors.

Visual messages

Many animals convey information to other members of the species through body coverings and adornment, as well as through gestures and body language. Visual displays can signal threat, show submission, attract a mate and even exert control over a social group.

artfarmer CC 2.0 3D

Bioluminescence

Many animals are bioluminescent. The glow they produce can be used as a signal to others of their species, such as fireflies signalling to a mate. Some deep sea fish use bioluminescence to signal other fish in the school.

Body position or facial expression

Social species with dominance hierarchies (e.g. wolves) use stereotyped expressions and body postures to avoid direct conflict with others in the group. The messages are well understood and rarely challenged.

Attraction

Some animals produce a stunning visual display to attract a mate. The plumage of some birds can be extremely colourful and elaborate, such as the peacock (above), the birds of paradise, and the lyrebird.

3. (a) Describe and explain the communication methods best suited to nocturnal animals in a forest habitat:

(b) Describe and explain the communication methods best suited to solitary animals with large home ranges:

4. Explain the role of dominant and submissive behaviours in animals with social hierarchies: