Data from: Ecological context and the probability of mistakes underlie speed choice

1.Movement is fundamental to the ecology of animals, and an animal's
choice of movement speed determines the duration, energetic costs, and
probability of success of any given activity. It is often assumed that
animals should use maximum speeds when escaping from predators, but an
increasing number of studies find animals rarely move as fast as they can
in nature because faster speeds come with a greater chance of mistakes.
Mathematical modelling suggests that, when escaping predators, prey
animals should optimise speeds to simultaneously outrun their pursuer and
minimise their probability of slipping. This can be particularly important
when running along narrow structures like branches. When foraging,
however, animals should avoid moving at high speeds, which are often
energetically costly and decrease the ability to detect food or predators.
2.In this study, we examined how trade-offs between speed and probability
of slipping influenced the speed choice of wild antechinus (Antechinus
mysticus) during escaping and foraging behaviours. We also examined how
this trade-off affected foraging behaviour. 3.Antechinus ran significantly
faster when escaping (1.207 ± 0.033 ms-1) than foraging (0.145 ± 0.002
ms-1), and slipped 37% more often during escapes. However, foraging
antechinus still slipped frequently on narrow branches, despite running an
order of magnitude more slowly than they did on wide branches.
Furthermore, antechinus slipped at lower speeds when foraging than they
did when escaping, suggesting that avoiding mistakes is less highly
prioritized when foraging. 4.Antechinus visited the feeding station
accessed by a wide branch more frequently (and ate more while there)
compared with feeding stations accessed by narrow branches, even when
those branches were 33% or 67% shorter. This suggests that foraging
decisions may be based on potential limitations to speed and the
probability of slipping over distance to cover. 5.Though activities such
as running can be fundamental to animals’ fitness, a general framework to
understand how animals select speeds in nature is still being developed.
We test the assumption that animals choose running speeds to minimise
their motor mistakes, and demonstrate the cost of mistakes is likely to be
different across ecological and behavioural contexts.