Résumé
The predator–prey space game and the costs associated with risk effects
are affected by prey 1) proactive adjustments (when prey modify their
behaviour in response to an a priori assessment of the risk level) and 2)
reactive adjustments (when prey have detected an immediate threat).
Proactive adjustments are generally well-studied, whereas the frequency,
strength and duration of reactive adjustments remain largely unknown. We
studied the space use and habitat selection of GPS-collared zebras Equus
quagga from 2 to 48 h after an encounter with lions Panthera leo.
Lion–zebra encounters generally occurred close to artificial waterholes
(< 1 km). Two hours after an encounter, zebras were more likely to
have fled than stay when the encounter occurred in more risky bushy areas.
During their flight, zebras selected grasslands more than usual, getting
great visibility. Regardless of their initial response, zebras finally
fled at the end of the night and reached areas located far from waterholes
where encounters with lions are less frequent. The large-scale flights
(∼4–5 km) of zebras led to a local zebra depression for lions. Zebras that
had fled immediately after the encounter resumed their behaviour of coming
close to waterholes on the following day. However, zebras that had
initially stayed remained far from waterholes for an extra 24 h, remaining
an elusive prey for longer. The delay in the flight decision had different
short-term consequences on the lion–zebra game. We reveal that the spatial
context of the encounter shapes the immediate response of prey, and that
encountering predators induces strong behavioural responses: prey flee
towards distant, safer, areas and have a constrained use of key resource
areas which are at the heart of the predator–prey game at larger
spatio-temporal scales. Nighttime encounters were infrequent (once every
35 days on average), zebra responses were short-lived (< 36 h) but
occurred over a large spatial scale (several km).