Data from: Avian top predator and the landscape of fear: responses of mammalian mesopredators to risk imposed by the golden eagle

Top predators may induce extensive cascading effects on lower trophic
levels, for example, through intraguild predation (IGP). The impacts of
both mammalian and avian top predators on species of the same class have
been extensively studied, but the effects of the latter upon mammalian
mesopredators are not yet as well known. We examined the impact of the
predation risk imposed by a large avian predator, the golden eagle (Aquila
chrysaetos, L.), on its potential mammalian mesopredator prey, the red fox
(Vulpes vulpes, L.), and the pine marten (Martes martes, L.). The study
combined 23 years of countrywide data from nesting records of eagles and
wildlife track counts of mesopredators in Finland, northern Europe. The
predation risk of the golden eagle was modeled as a function of territory
density, density of fledglings produced, and distance to nearest active
eagle territory, with the expectation that a high predation risk would
reduce the abundances of smaller sized pine martens in particular. Red
foxes appeared not to suffer from eagle predation, being in fact most
numerous close to eagle nests and in areas with more eagle territories.
This is likely due to similar prey preferences of the two predators and
the larger size of foxes enabling them to escape eagle predation risk.
Somewhat contrary to our prediction, the abundance of pine martens
increased from low to intermediate territory density and at close
proximity to eagle nests, possibly because of similar habitat preferences
of martens and eagles. We found a slightly decreasing trend of marten
abundance at high territory density, which could indicate that the
response in marten populations is dependent on eagle density. However,
more research is needed to better establish whether mesopredators are
intimidated or predated by golden eagles, and whether such effects could
in turn cascade to lower trophic levels, benefitting herbivorous species.