Evaluation of methods to detect the mongoose, an expanding mesocarnivore

    Researchers from IREC, IESA-CSIC and the University of Malaga have evaluated different methods for the detection of the mongoose (Ichneumon herpes), a carnivore spreading in southwestern Europe. Their results show that the combination of various methods provides more accurate and less biased occupancy estimates than those obtained through simple methods.


    El Egyptian mongoose (Ichneumon herpes) It is the only mongoose (Family Herpestidae) currently present naturally in Europe. Its distribution is restricted to the southwest of the Iberian Peninsula, where recent studies suggest that it could be expanding. However, its current situation in Spain is not precisely known due to the lack of methodological studies.

    Unlike the rest of Iberian carnivores, the mongoose is a species with completely diurnal habits. This means that it is frequently observed in broad daylight, which contributes to a perception of high abundance and population increase. In this context, the hunting sector calls for measures to limit their populations and stop their expansion, based on their perception of a great impact on small game species. However, In Castilla-La Mancha its distribution is unknown, if it is really expanding and what is the impact on its prey.

     

    Photo of mongoose obtained by a camera-trap during this research work (MELOCAM Project).

    These are some of the questions that he tries to answer.MELOCAM project: The mongoose in Castilla-La Mancha: distribution, abundance, population trends, effects on its prey and social perception (SBPLY/17/180501/000184)”, which is developed by scientists from the Research Group in Game Resources and Wildlife Management of the Instituto de Investigación en Recursos Cinegéticos (IREC – CSIC, UCLM, JCCM) in collaboration with researchers from the Institute for Advanced Social Studies (IESA-CSIC) and the University of Malaga, and financed by the Castilla-La Mancha Community Board and FEDER funds from the European Union.

    Various methods are commonly used to detect carnivorous species, whose elusive behavior often makes direct observation difficult. The most used are, among others, photo-trapping, the search for clues and live captures. However, each method has its advantages and disadvantages, and It is necessary to know very well which are the most appropriate methods in each case and for each species in order to obtain the most accurate estimates of population distribution..

     

    Mongoose droppings (MELOCAM Project).

    Thus, the aim of this study was compare different methodologies and their possible combinations to optimize the distribution estimates of the mongoose. To do this, occupancy models were used to identify the most cost-efficient method or combination of methods (ie, with high precision, low bias and low cost) to assess the distribution of the species.

    The study was carried out in four areas of central Spain (in particular, in the Autonomous Community of Castilla-La Mancha) where the presence of mongoose was previously known. Four different methods were used: camera traps, double hair traps baited with chicken, single hair traps without bait, and searching for clues such as footprints and droppings.s. These methods were replicated in 10 sampling units within each of the 4 study areas. Using occupancy models, the probability of detection was estimated for each method and its possible combinations in each area.

    The results of the work show that the simplest, most precise and least biased method was photo-trapping, followed by the search for evidence.. In contrast, hair traps, both baited and unbaited, produced biased occupancy estimates. However, camera traps were the most expensive method, while unbaited hair traps had the lowest cost. The combination of the four methods produced the best model in absolute terms (higher probability of detection and higher precision of the occupancy estimate)..

     

    Baited double hair trap (in the center of the image) used in the present study (MELOCAM Project).

    This work shows that the combination of various methods provides more accurate and less biased occupancy estimates than those obtained through simple methods. Even so, a biased method could contribute to improving the estimates if combined with another that is precise and unbiased. It is recommended that in future studies of the distribution of carnivore species, not only the precision and bias of the methods should be considered, but also the cost and effort required by each method to obtain more cost-efficient results.

    The scientific publication of this research is available at: