Why is courtship behaviour necessary?
No individual lives forever. Reproduction is therefore important to all organisms as it is the means by which a species can survive over time. Each individual tries to ensure that their DNA is passed on, through the reproductive process, to the next generation. The females of most species only produce eggs at specific times, often as little as once a year. It is therefore important to ensure that mating is successful and that the offspring have the maximum chance of survival. Courtship behaviour helps to achieve this by enabling individuals to:
- recognise members of their own species - to ensure that mating only takes place between members of the same species because only members of the same species can produce fertile offspring
- identify a mate that is capable of breeding - because both parents need to be sexually mature, fertile and receptive to mating
- form a pair bond - that will lead to successful mating and raising of offspring
- synchronise mating - so that it takes place when there is the maximum probability of the sperm and egg meeting
Courtship behaviour (2)
The females of many species undergo a cycle of sexual activity during which they can only conceive during a short time. They are often only receptive to mating for a period around the time when they produce eggs. Courtship behaviour is used by males to determine whether the females is at this receptive stage. If she responds with the appropriate behavioural response, countship continues and is likely to result in the production of offspring. If she is not receptive, she exhibits a different pattern of behaviour and the male ceases to court her, turning his attentions elsewhere.
During courtship, animals use signals to communicate with a potential mate and with members of their own sex. Typically a male carries out some action. This action acts as a stimulus to the female, who responds with a specific action of her own. Her reponse acts as a stimulus to the male tocarry out a further action. The ritual proceeds in this way in what is called a stimulus-response chain. The chain of actions is the same for all members of a species but differs for members of different species. In this way they may be prepared to mate. The longer the courtship sequence continues, the more likely it is that mating will result. If at any point one of the pair fails to respond appropriately, then the courtship sequence ends
- The courtship display of a male mallard duck has around 10 display elements.
- These include shaking the tail, flicking the head, alternately raising the head and tail, shaking the bill and nodding the head while swimming.
- One particular display called the grunt-whistle involves lifting the breast out of the water while arching the head downwards followed by a sharp whistle and a deep grunt.
- These elaborate displays are found in closely related duck species.
- However in some species certain elements are omitted, while in other the order in which each element is performed is different.