The go-to species for personality research has, more often than not, been the easy-to-study Great Tit. Great Tits can’t be asked to fill out a questionnaire or to undertake a psychometric test, and so scientists have inferred their personalities from their outward behaviours. 

Individual Great Tits have been classed as fast, slow or intermediate-speed explorers by researchers, by examining characteristics which correlate positively with these groups such as aggressiveness, boldness and risk-taking. Studies have found that personality is repeatable in individual Great Tits, which means that different studies with different methods have arrived at the same results for the same birds. It also appears to be heritable within Great Tit families, and does not seem to be determined by age, body condition or sex.

Under different environmental conditions, it seems that opposing personality traits can be beneficial. In some years, beechmast – an important winter food source for Great Tits and other birds – is particularly abundant. This leads to lower levels of competition between Great Tits during winter, but because more birds survive, competition for breeding territories in the spring is fierce. In these scenarios, fast-exploring adult males and slow-exploring adult females tend to have the highest survival rates. The opposite has been found in years when beechmast is less abundant. So, why does this happen?

Because female Great Tits are subordinate to males in winter feeding flocks, being an aggressive, fast explorer is likely to be most beneficial for females when winter food is scarce. Males have better access to food than females, but after a good mast year when there are lots of rival males competing for territories, being a fast-exploring male is likely to be most beneficial. It is not yet clear, however, why fast-exploring adults of either sex experience lower survival rates than slow-exploring adults in some years. Clearly, there is a cost to being a fast explorer, the nature of which requires more research.

In some years, then, it pays to be an aggressive, fast-exploring bird while in others it does not. This variability certainly promotes, if not fully explains, the preservation of different personality types within Great Tit populations. Interestingly, Great Tits with intermediate personality types have been found, on average, to have both the greatest breeding success and highest life expectancy – so perhaps being somewhere in the middle is best!