Shaping carnivore communities by predator control: competitor release revisited

Abstract

The traditional way to deal with hunting interests is often focused on predator control. This approach requires a detailed understanding of predator responses to game management. Control methods can be non‐selective and, consequently, can potentially have a negative impact on non‐target predator species, affecting carnivore guild. In order to assess the potential risks associated with non‐selective predator control in the presence of intraguild competition, the classical Lotka–Volterra competition model was used, but with two additional factors: a linear factor for capture mortality (mortality caused by predator control) and a factor for vacated niche occupancy associated with immigration. Simulation in a scenario with three species revealed that one of them, the red fox Vulpes vulpes, which presented the highest intrinsic growth rate, can show population increases even under moderate control, whereas the population of European badger Meles meles, with a lower intrinsic growth rate, was reduced and, in some cases, may even become extinct. Lastly, the stone marten Martes foina presented a differential response, depending on the removal intensity and strategy employed. This behaviour is compatible with the results observed in a Mediterranean environment subjected to two types of game management: non‐selective predator control (culling) and no control. In areas with non‐selective control and moderate predator removal, the red fox population remained stable, while the stone marten and the European badger populations reduced markedly or disappeared.

Differential response of a carnivore community to predator control: a spatio-temporal observational study

“…In contrast, the frequency of occurrence of European badger and stone marten decreased. The observed differences between PHAw and PHAc in frequency of occurrence are consistent with the species response to removal in the presence of competitors (Casanovas et al 2012). The results of the simulation study with the competitor release effect model have shown that the factors that most affect population dynamics are removal intensity and strategy employed, intrinsic growth rate and immigration.…”

“…In general, the effect of predator control varies depending on the selectivity, intensity, scope and duration of the programme, and the biology of the species involved (Reynolds et al 1993;Harding et al 2001;Baker & Harris 2006;Duarte et al 2012). When control is maintained over time, the interactions that occur can be explained by the mechanisms of the competitor release effect (Caut et al 2007;Casanovas et al 2012). When the control is not maintained over time, or only covers small areas, the results are usually very limited (Reynolds et al 1993;Harding et al 2001;McDonald & Harris 2002).…”

“…They are basically omnivorous, nocturnal or crepuscular, and show a broad overlap in resource use (habitat and food) (Larivière & Jennings 2009;Sillero-Zubiri 2009). The intrinsic growth rate of the red fox (r = 1.1) is greater than that of the European badger (r = 0.46) or stone marten (r = 0.62) (Casanovas et al 2012). Red fox dispersal and colonisation ability is superior to that of European badger and stone marten (Blanco 1986;Libois & Waechter 1991;Ferrari 1997).…”

Mesopredator release facilitates range expansion in fisher

“…The limited range expansion of the pacific fishers does not match our predictions, despite reductions in their predator community, bans on their harvest and five translocation efforts (Lewis et al ., ). The cause of limited range expansion for pacific fishers is unclear, but could be influenced by multiple factors including variation in abundance of fishers and other predators compared with other regions, anthropogenic pressures and multiple bottom‐up processes (Casanovas et al ., ; Kennedy et al ., ; Pasanen‐Mortensen et al ., ; Schuette et al ., ). Recent mortality data suggest that predation by cougars and bobcats are frequent in pacific fisher populations, further underscoring the importance of larger predators to fisher population dynamics (Wengert et al ., ).…”

Mesocarnivore community structure under predator control: Unintended patterns in a conservation context

“…Although extremely relevant, the impacts of game management and predator control efforts on Iberian mesocarnivore community structure and composition are poorly understood (but see [4,5]) and empirical data on community shaping effects of predator control measures is still scarce (see [25,26]). Impacts of culling activities on predators and the effectiveness of removal generally vary according to the selectivity, intensity and duration of the methods applied, as well as on the target species biology, such as life-history traits, and behaviour or habitat preferences [27].…”