Direct and indirect interactions with vegetation shape crocodylian ecology at multiple scales

As one of the world's largest predators of freshwater environments, crocodylians play an important role in shaping their community. In turn, many aspects of crocodylian life histories are influenced and have been shaped by characteristics of their environment, especially vegetation. However, our understanding of just how vegetation impacts crocodylian life histories remains limited, particularly in regard to indirect interactions. Such interactions can be critical for understanding population dynamics and, therefore, for informing conservation management decisions. We reviewed contemporary understanding of these plant–crocodylian interactions in peer-reviewed journals and the grey literature, synthesising life history-shaping dynamics against aspects of their ecology. We then conceptualised how global environmental change, including climate change, species invasions and land use change, may threaten these critical dependencies, and how future conservation plans need to account for these pressures. We identified five primary aspects of crocodylian ecology—habitat selection, nesting ecology, communication, physiology, and feeding ecology—that are probably shaped by vegetation interactions at different spatial scales. These interactions include direct and indirect impacts, with both positive and negative outcomes from a crocodylian perspective. Anthropogenic impacts on environments via global environmental change drivers is causing unprecedented change to vegetation dynamics. What is often overlooked is how these changes impact large aquatic predators such as crocodylians. Our synthesis shows that while many impacts can be identified, their magnitude and mechanism are not well understood, making management driven mitigation challenging. We recommend that future studies prioritise quantifying how vegetation communities shape the suitability of crocodylian nest sites, and how to best detect the fingerprint of impacts caused by invasive alien plants on demographic change in crocodylians over longer durations. An improved understanding of the impact of vegetation impacts on crocodylians is essential for building effective conceptual frameworks and management agendas for the conservation of these iconic reptiles.