Animal personalities are important in a changing world

Personalities are not limited to humans; they are ubiquitous across the animal kingdom and shape how individuals, species and populations interact with each other and the natural world. Some individuals are bold and more likely to take risks, such as exploring new habitats. Others are shy and cautious, and avoid novelty whenever possible. Because these personality traits can affect survival, reproduction and interspecific interactions, they might determine how organisms respond to a changing world.

This concept of animal personality (also referred to as behavioural syndromes) was initially developed by Sih and colleagues in 2004. The authors proposed that individuals are born with fixed behavioural syndromes (defined as consistent responses to stimuli across different contexts), which limit their ability to optimize their behaviour to align with changes in their physical or social environment. For example, being bold and aggressive is advantageous while foraging, but can lead to reduced courtship success and lower overall fitness. This framework challenges the assumption that behaviour is flexible and context dependent. Instead, Sih et al. argued that correlated behaviours and trade-offs maintain behavioural syndromes even under directional selection.