Predator-mediated apparent competition persists in a rapidly changing
Subarctic ecosystem
Abstract
The Alternative Prey Hypothesis (APH) states that predators switch to
relatively more abundant prey when their main prey is scarce. In the
High Arctic, lemming population cycles indirectly affect predation risk
on alternative prey such as shorebird nests as they share a main
predator, the arctic fox. In this study, we examined the indirect
effects of arvicoline rodent cycles on alternative prey in the Subarctic
where arctic and red fox coexist as predators of primary (lemmings,
voles) and alternative prey (shorebird nests). Using 10 years of field
data, our results indicate that interannual variation in daily nest
survival of Dunlin was best explained by an interactive effect of
arvicoline rodent abundance and arctic fox (not red fox) abundance.
During high rodent years, shorebird nest survival appeared to be
buffered from variation in arctic fox abundance but when rodents were
absent, nest survival declined. We found no relationship between
shorebird nest survival and red fox abundance despite red foxes being
found in much higher abundance in the study area. Our results indicate
that despite the presence of other predators and multiple primary prey
species, predator-mediated interactions common to High Arctic sites,
still hold true for the Subarctic in regards to the arctic fox,
arvicoline rodents and shorebirds.