Predicting the potential demographic impact of predators on their prey: a comparative analysis of two carnivore–ungulate systems in Scandinavia

Abstract

1. Understanding the role of predation in shaping the dynamics of animal communities is a fundamental issue in ecological research. Nevertheless, the complex nature of predator–prey interactions often prevents researchers from modelling them explicitly.2. By using periodic Leslie–Usher matrices and a simulation approach together with parameters obtained from long-term field projects, we reconstructed the underlying mechanisms of predator–prey demographic interactions and compared the dynamics of the roe deer–red fox–Eurasian lynx–human harvest system with those of the moose–brown bear–gray wolf–human harvest system in the boreal forest ecosystem of the southern Scandinavian Peninsula.3. The functional relationship of both roe deer and moose λ to changes in predation rates from the four predators was remarkably different. Lynx had the strongest impact among the four predators, whereas predation rates by wolves, red foxes, or brown bears generated minor variations in prey population λ. Elasticity values of lynx, wolf, fox and bear predation rates were −0·157, −0·056, −0·031 and −0·006, respectively, but varied with both predator and prey densities.4. Differences in predation impact were only partially related to differences in kill or predation rates, but were rather a result of different distribution of predation events among prey age classes. Therefore, the age composition of killed individuals emerged as the main underlying factor determining the overall per capita impact of predation.5. Our results confirm the complex nature of predator–prey interactions in large terrestrial mammals, by showing that different carnivores preying on the same prey species can exert a dramatically different demographic impact, even in the same ecological context, as a direct consequence of their predation patterns. Similar applications of this analytical framework in other geographical and ecological contexts are needed, but a more general evaluation of the subject is also required, aimed to assess, on a broader systematic and ecological range, what specific traits of a carnivore are most related to its potential impact on prey species.

Decomposing risk: Landscape structure and wolf behavior generate different predation patterns in two sympatric ungulates

“…Landscape structure also can affect hunting success of predators on prey individuals of different age (Gorini et al 2012), thus influencing the age composition of kills and the resulting demographic impact of predation (Gervasi et al 2012). …”

Importancia del conejo zacatuche (Romerolagus diazi) en la dieta del coyote (Canis lastrans) y del lince (Lynx rufus)

“…La información sobre la selección de presas se generó con el propósito de conocer si el conejo zacatuche es consumido en función de su disponibilidad en el ambiente o si es seleccionado como presa por uno o ambos depredadores. De ser este caso, el consumo selectivo de zacatuche podría representar una presión más sobre este lagomorfo catalogado en peligro de extinción, debido a que la depredación selectiva puede provocar una disminución de las poblaciones de las presas (Vucetich et al 2005;Gervasi et al 2012;Ripple et al 2013). …”

“…La depredación puede tener efectos serios en las poblaciones de las presas (Nilsson 2001;Vucetich et al 2005;Gervasi et al 2012). En ambientes estables, las interacciones depredador-presa se mantienen constantes (Begon et al 1996).…”

Sheep farming and large carnivores: What are the factors influencing claimed losses?

“…When implementing mitigation measures, a key element is to understand the ecological mechanisms that drive predator conflicts with livestock. Important factors that are likely to influence losses of sheep to predators are the kill rates by the different predator species, predator densities, prey densities and the amount of time livestock is available as prey (e.g., Gervasi et al 2012, Gervasi et al 2014). Patrolling of pastures as it is practiced today in Norway is not expected to decrease kill rates much as it does not place any form of ''barrier'' between sheep and predators.…”