Isabel Mate

Shaping carnivore communities by predator control: competitor release revisited

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.

Habitat selection by Southern water vole ( Arvicola sapidus ) in riparian environments of Mediterranean mountain areas: a conservation tool for the species

The Southern water vole, Arvicola sapidus, is endemic to the Iberian Peninsula and France. Despite being catalogued as vulnerable, our current knowledge of this species is not sufficient to establish measures for its conservation and recovery, particularly in riparian zones of Mediterranean mountain areas. The aim of this study was to identify factors related to habitat configuration that determine the presence or absence of the species in the Montsant River. Specifically, we associated the presence/absence of this arvicolid rodent with composition of vegetation, river bank morphology, and watercourse characteristics. The results suggest that, in this area, the most favorable places for the species are those with a high degree of cover of herbaceous plants (mainly helophytes) and moderate to low levels of tree and shrub cover; gently sloping banks and a soft substrate; and the presence of water, with moderate to high stream widths and depths. In addition, we developed a classification method which allowed us to classify and characterize habitat conditions: the optimal scenario (preferential for arvicoline establishment), the suboptimal scenario (whose use is related to opportunities to find best scenarios), and the hostile scenario (not acceptable for use). In such riparian areas, the results revealed that the Southern water vole is a specialist in terms of habitat selection, but behaves as a generalist in terms of occupancy. Its ability to adapt to suboptimal conditions widens the options for managing Southern water vole populations, and indicates that the maintenance and rehabilitation of habitat along continuous stretches of river is the most effective approach to achieving self-sustaining populations.

Selectivity of mammalian predator control in managed hunting areas: an example in a Mediterranean environment

Abstract Predator control has frequently been applied in the management of private hunting areas in recent decades. This study analyzes capture records taken during predation control carried out in areas with hunting management, in a Mediterranean environment, in the northeast of the Iberian Peninsula between 1991 and 1999. Whether predator control complied with the law during this period is discussed, and the efficacy and selectivity of the methods are evaluated. Results reveal that predation control did not always comply with the law. They also indicate that the methods used were not selective, as they caught legally protected species during part of the study period. The results are examined with a view to establishing a rational management program for hunting areas and species conservation.

Spatial organization and intraspecific relationships of the southern water vole (Arvicola sapidus) in a Mediterranean mountain river: what is the role of habitat quality?

An understanding of population dynamics, especially in endangered species that present metapopulation structures, such Arvicola sapidus, is important to gain knowledge of the dispersal and patterns of both occupation and space use. Here, we use radio tracking to report for the first time the relationship of the southern water vole with the environment in a Mediterranean mountain riparian area and also the relationships between individuals. Along the Montsant River, the size of the home ranges, the average distance travelled daily, the population density and the habitat quality were contrasted. In the subsection with better quality habitat, both the home ranges and distances travelled were smaller than in the subsection with poorer quality habitat, whilst population density was higher in the subsection with better quality habitat. Interactions (static and dynamic) between individuals reflected low sociality, especially between members of different groups. Within a group, adult males did not interact, but interactions between male and female adults intensified during the reproductive period. The home ranges of individuals changed with the emergence of new available gaps and in response to reproduction needs. Tracking a dispersant young male showed a trajectory in stages and made obvious the high risk of predation during this period. Our results here, and previously, indicate the possible effect of habitat quality on space use and relationships between individuals, emphasising the importance of the quality and structure of habitat in the conservation of the southern water vole.

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

Abstract Predator control has historically shaped management towards minimising predator pressure on sensitive species in most hunting and protected areas. Despite widespread use, few studies of medium-sized carnivores have evaluated such control. To fill this void, we studied the effect of control on shaping a carnivore community consisting of European badgers Meles meles Linnaeus, 1758, stone martens Martes foina Erxleben, 1777 and red foxes Vulpes vulpes Linnaeus, 1758, in the Serra de Montsant area (NE Spain), and we report the recovery dynamics for different habitats (forest, scrubland and cultivated land) over time (3 years) when that control was halted. The results show that non-selective predator control is inadequate to reconcile the conservation of ecosystems with hunting. Specifically, it favours the frequency of occurrence of red foxes, which are the main consumer of small game species, and also reduces the frequency of occurrence of European badgers and stone martens, which are protected species. The recovery or regression sequence was observed over time in an area where there had previously been control, and was compared with the point of reference provided by an uncontrolled area. The results show the recovery of European badgers (135% over 3 years) and stone martens (285% over 3 years), and the regression of red foxes (–10% over 3 years) when control is halted. Monitoring the different habitats, European badgers recover first on cultivated land, then scrubland and more slowly in forest. Stone martens recover first in forest, and then scrubland and cultivated land. In contrast, red foxes maintain their numbers in scrubland, and decline slightly in forest and on cultivated land. The observed preferences have been associated with the capacity to meet basic needs of food, protection and balance with competitors.