Outline and evaluate two different signalling systems used by non-human animals.

Visual signals are also often used in conflict situations where animals are able to express there disliking of the opposition. This is done by many different animals, for instance, canines will often bare there teeth as a warning. This allows the opponent to assess the size and strength of the other individual as it can then be seen which individual is more likely to succeed in combat. This is often an effective way of claiming territory as it allows animals to keep others at bay to avoid losing territory. Tinbergen and Perdeck suggested that visual signals are also often used for parents to communicate with their young. For instance, the orange spot on a herring gull enables chicks to signal when they wish to be fed.

Visual communications are seen all over the animals world as it can convey a vast amount of information in a short amount of time. These types of signals are also easily detected as often bright colours and a variety of shapes are used, allowing displays to be easily recognised. However, visual signals cannot always be used as they can only be detected within a certain proximity. These types of signals would hold little use to animals who live in dense undergrowth as the signal would not be visible due to obstructions. A lack of light may also cause a problem, as once again it reduces visibility meaning this form of signal would carry little use as the receiver would be unable to interpret the signal.

Another method of communication in the animal world is with the use of chemicals known as pheromones. Animals, especially mammals and insects, are often able to emit certain chemicals which can then be recognised by the correct receiver. These chemicals are often small molecules, allowing easy dispersion. They are however, short lived to allow quick changes to the signal, an example of this would be ants using chemicals to signal alarm. Pheromones, just like visual signals, are often used to attract a mate. Moths often use this as their method of sexual selection as it is fast and effective.

Another use of chemical signalling is to mark territory. Chemicals used to do this, unlike those used to send signals of danger, can be extremely long lasting so the message can be detected by other animals even if the sending of the message is not present. Often chemical markers are positioned around an animals territory to ward off any unwanted company. This is effective as the signal will be present for a long time, in both light and dark. Faeces is also often used along with pheromones to help mark territory as it gives other animals awareness that the territory is occupied. This can be useful for many reasons; individuals may wish to keep food and offspring safe from intruders for instance.

Chemical signals have a vast range as the time of day or type of environment does not affect them, allowing other animals to detect them even if they are not in an immediate proximity. These types of signals can also be private between species as specific receptors are needed in order to interpret these signals. This is effective as it allows messages between species to occur without interference from predators. It can however be a slow method of signalling, unlike visual signals. It also lasts a certain amount of time which cannot then be altered which may lead to interference with previous of new signals.