Behaviour can be so well adapted to an animal's way of life that the animal seems to ‘know’ what to respond to, what to do and when to do it. Thus partridges and small rodents ‘know’ that the most effective defence against a hawk flying overhead is to flatten themselves on the ground and remain motionless since the hawk, which is very sensitive to movement, is least likely to see them. Most of us have experience of wasps that know about sweet drinks or mosquitoes that know where to find exposed human flesh.
Using the word ‘know’ in this context does not necessarily imply that animals are consciously thinking about what they are doing (although they may be, as we discuss in Chapter 5). Animals may ‘know’ things about their environments in the same way that a heat-seeking missile knows how to find its target or a computer knows how many mistakes you have made in the course of a game. In other words, quite simple unconscious mechanisms are capable of giving rise to what we might refer to as knowledge. When we ask causal questions about behaviour, we are asking what this knowledge is and how the animal uses it.