Risk trade-offs in a heterogeneous landscape: red deer vary their
fine-scale behavioural responses to large carnivore cues
Abstract
Behavioural changes of prey towards large carnivores can have profound
impacts on prey populations and the ecosystems they inhabit. However,
European studies have thus far only found limited support for prey
behavioural changes to returning large carnivores. We examined the
trade-off between forage quality and perceived predation risk of an
ambush (Eurasian lynx; Lynx lynx) and cursorial predator (wolf; Canis
lupus) on the behavioural response of red deer (Cervus elaphus) in an
experimental set-up within semi-natural grasslands and forest patches.
We hypothesized that red deer would i) reduce visitation frequency and
duration but increase their time spent vigilant in the presence of
olfactory cues of large carnivores, ii) show a stronger response towards
the scent of wolf with increasing distance from the forest edge in open
areas and a stronger response towards lynx in forested areas independent
of distance, and iii) show a stronger response in areas with lower
forage quality. We tested these using camera trap video data on 76 plots
at different distances within the forest and open areas (mown and
unmown) in the Grafenwöhr military training area, Germany. Within three
trials, we applied each of the following scent treatments to each plot:
wolf urine-scat, lynx urine-scat, and horse urine-dung. To analyse
forage quality, we determined crude protein concentration from the
herbaceous vegetation by near-infrared spectroscopy. Red deer avoided
open areas further away from the forest edge when wolf scent was
present, whereas an increase in vigilance was found in forested areas
towards lynx scent. In contrast to plots with horse and lynx scent, red
deer visitation frequency on plots with wolf scent remained low despite
increasing crude protein concentration. Our research is the first to
experimentally show that large carnivores with different hunting mode
induce different changes in the foraging behaviour of free-ranging red
deer.