Following the trail: factors underlying the sudden expansion of the Egyptian mongoose (Herpestes ichneumon) in Portugal

Species range-limits are influenced by a combination of several factors. In our study we aimed to unveil the drivers underlying the expansion of the Egyptian mongoose in Portugal, a carnivore that was confined to southern Portugal and largely increased its range during the last three decades. We evaluated the expansion of the species in three periods (1980-1990, 1990-2000 and 2000-2010), by projecting the presence/absence data of the species in each temporal range and proposed four hypotheses to explain this sudden expansion associated to changes in the barrier effects of human infrastructure and topographic features, and in the availability of suitable areas due to climate change or land use. An exploratory analysis was made using Spearman rank correlation, followed by a hierarchical partitioning analysis to select uncorrelated potential explanatory variables associated with the different hypotheses. We then ran Generalized Linear Models (GLM) for every period for each hypothesis and for every combination of hypotheses. Our main findings suggest that dynamic transitions of land-use coupled with temperature and rainfall variations over the decades are the main drivers promoting the mongoose expansion. The geographic barriers and the human infrastructures functioned as barriers for mongoose expansion and have shaped its distribution. The expansion of the Egyptian mongoose across the Portuguese territory was due to a variety of factors. Our results suggest a rapid shift in species range in response to land-use and climate changes, underlining the close link between species ranges and a changing environment.

Predictive niche modelling to identify potential areas of conflicts between human activities and expanding predator populations: a case study of game management and the grey mongoose, Herpestes ichneumon, in Spain

Context. The grey mongoose, Herpestes ichneumon L., is a protected species in Spain. Populations of grey mongoose are currently increasing in numbers, and potential conflicts with human interests involving predation of small-game species, may arise in the near future. Aims. We predicted potential suitable areas for the expansion of grey mongoose by using a niche modelling approach to detect areas of conflict with small-game hunting activities. Methods. We compared these areas with regions in which small-game hunting is an important economic activity. To produce a niche-suitability map we used Maxent and an internal (data-splitting) validation to assess the predictive performance of the model. Areas in which small-game hunting is important were identified by using a rabbit-abundance index. Key results. On the basis of suitability modelling, populations of grey mongoose will expand into southern and central Spain. The variables with higher predictive power are mainly climatic, although some mosaic habitat types are also important. Internal validation reveals a strong correspondence between predicted and observed records. The overlap of high-suitability areas with areas assigned with a high rabbit-abundance index indicated the existence of large regions of potential conflict with hunting interests. Conclusions. Predictions of niche modelling can be used to detect conflict areas between expanding species and human interests. As a consequence of the expansion of the grey mongoose, the incidence of non-selective predator control may increase, thereby posing a threat to other protected predators. Implications. Identified areas of likely conflict should be prioritised to delineate careful management programs in terms of people education, surveying, incentives and the detection of illegal predator-control activities.

Factors determining "gaps" in the distribution of a small carnivore, the common genet (Genetta genetta), in central Spain

We studied the pattern of distribution of the common genet (Genetta genetta) in areas in mountains and plains of central Spain, in the middle of the range of the species. We evaluated the role of temperature, rainfall, and habitat features in determining the ecological limits of genet distribution. Genets were very scarce on plateaux and the upper parts of the mountains, but were widely distributed in lower mountain areas. Genets were present in areas with abundant shrub cover, high mean of the mean minimum temperature and high mean of mean winter temperatures. Survey routes at the same altitude (<1000 m) in the mountains (genets abundant) and on the plateaux (genets very scarce) also differed in some of these variables, with low values on the plateaux for shrub cover, mean of the mean minimum temperatures, mean of the mean winter temperatures, and annual rainfall. Genets originated in Africa, therefore they are probably ill-adapted (morphologically and physiologically) for the cold conditions predominating in most of central Spain. Their preference for shrubby habitats may be linked to a greater availability of food and low risk of predation. Intermediate levels of rainfall may be correlated with higher temperatures, the key factor hypothesized to affect the distribution of this species. The distribution of the common genet fits a multimodal model, with peaks (presence) and valleys (absence) in the middle of its range, indicating that location in a particular part of the range is not a prior indicator of habitat suitability for the species.