A combination of different behaviors can often exist concurrently in a population, and consistent behavioral differences among individuals can often be considered "personalities." Personality differences can be conceptualized as consistent long-term phenotypic behavioral differences among individuals.
Boldness/shyness is one of the most stable personality variables. But evolutionarily based animal behaviorists argue that there is no reason that natural selection should necessarily select for boldness or shyness as a general personality trait. Rather, individuals may be bold in some contexts and shy in others, depending on the costs and benefits associated with the behavioral contexts being examined.
With the exception of work on humans, compared to many of the subjects discussed throughout this book, the number of personality studies ethologists have undertaken is relatively small. As such, the detailed cost/benefit analyses that we'd ideally like to have are rare. That being said, there are enough case studies across a wide array of species to provide us with some understanding of animal personality traits.
Studies such as those on the behavior and genetics of alternative strategies in lekking birds allow us to rethink mating strategies and heritability in the framework of personality research.
Cultural transmission of information affecting animal personality has been uncovered in seven long-term studies of chimpanzees in Africa. Stable innovative patterns of behavior are spread within groups of chimpanzees through imitation. But behaviors and personalities across different populations are very different.
How an animal copes with everyday, as well more extreme, stressors can have a profound impact on its health. Two general coping styles emerge from studies across a wide variety of animals, where a coping style can be defined as"a coherent set of behavioral and physiological stress responses which is consistent over time and which is characteristic to a certain group of animals." These two styles are referred to as the proactive or "active response" and the reactive or "conservation-withdrawal" response. The proactive coping style entails territorial control and aggression, while the reactive coping style is characterized by immobility and low levels of aggression.
The study of animal personality has potential practical implications for conservation biology, human-animal interactions, farming, and many other areas, including preventing the death of livestock and aiding people with disabilities.