Abstract:
Concern for megafauna is increasing among scientists and non-scientists.
Many studies have emphasized that megafauna play prominent ecological
roles and provide important ecosystem services to humanity. But, what precisely
are ‘megafauna’? Here, we critically assess the concept of megafauna
and propose a goal-oriented framework for megafaunal research. First, we
review definitions of megafauna and analyse associated terminology in
the scientific literature. Second, we conduct a survey among ecologists and palaeontologists to assess the species traits used to identify
and define megafauna. Our reviewindicates that definitions
are highly dependent on the study ecosystem and research
question, and primarily rely on ad hoc size-related criteria.
Our survey suggests that body size is crucial, but not necessarily
sufficient, for addressing the different applications of
the term megafauna. Thus, after discussing the pros and
cons of existing definitions, we propose an additional
approach by defining two function-oriented megafaunal
concepts: ‘keystone megafauna’ and ‘functional megafauna’,
with its variant ‘apex megafauna’. Assessing megafauna
from a functional perspective could challenge the perception
that theremay not be a unifying definition ofmegafauna that
can be applied to all eco-evolutionary narratives. In addition,
using functional definitions of megafauna could be
especially conducive to cross-disciplinary understanding
and cooperation, improvement of conservation policy and
practice, and strengthening of public perception. As megafaunal
research advances, we encourage scientists to
unambiguously define how they use the term ‘megafauna’
and to present the logic underpinning their definition.
