Variation in the behaviour of an obligate corallivore is influenced by resource availability

Abstract Marine environments are subject to increasing disturbance events, and coral reef ecosystems particularly vulnerable. During periods of environmental change, organisms respond initially through rapid behavioural modifications. Whilst mean population level modifications behaviour well documented, how these shifts vary between individuals, the relative trade-offs that induced, unknown. We test whether frequency time invested in different behaviours varies both within individuals with varying resource availability. To do this, we quantify differences four key categories (aggression, exploration, feeding sociability) at two sites availability, using an obligate corallivore butterflyfish species ( Chaetodon lunulatus ). Individuals on a low site held larger territories, investing more which was traded off less aggression, sociability. Repeatability measures indicated could plausibly be driven by plasticity habitat patchiness territories. By combining population-level means, co-correlation individual-level analyses, reveal potential mechanisms behind variation C. due Significance statement Using observational methods, identify corallivorous ) high site. use combination density surveys, territory mapping observation methods comparative analysis relate directly environment it occurs. Bringing together insights from game theory optimal foraging, also our results highlight understanding correlations can inform extent plastic or fixed. Furthermore, considering multiple correlated, move away exploring individual isolation provide in-depth insight into affect responses declining