Animals gather information about their surroundings, including their social environment, using a wide range of sensory modalities. Variation in reception, processing and interpretation of information (cues or signals) can lead to differences in how individuals perceive their local environment. Yet, how individual differences in environmental perception influence behaviour and eco‐evolutionary processes has been largely overlooked. Here, we highlight the importance of investigating such individual variation by focusing on perceived density, i.e. the individual's assessment of local conspecific density. This perceived density may diverge from the absolute number of conspecifics in a given area and may vary between individuals depending on their phenotype. Recognizing that not only absolute density but also individuals' perception of that density shapes behaviour offers novel insights into social and ecological dynamics. We summarize how individuals sense their environment and identify factors shaping variation in sensory uptake and processing. We argue that differential perception of the environment affects decision making and in turn impacts the way in which individuals realize their ecological niches, which occurs via three main processes: niche choice, niche conformance and niche construction. We propose that perceived density can have eco‐evolutionary consequences by influencing resource use, competition and ultimately selective pressures. Finally, we provide methodological guidelines for studying perceived density, including experimental approaches and potential proxies for quantifying individual differences in environmental perception. By integrating the concept of perceived density into evolutionary and ecological perspectives, we aim at gaining a deeper understanding of how individual variation in environmental perception affects population‐wide ecological patterns and evolutionary trajectories.
Berthelsen et al. (Fri,) studied this question.