Increases the accuracy of spatially explicit capture and recapture models

    The integrated model developed in this study makes it possible to accurately estimate population density for fauna species that cannot be easily distinguished at the individual level.


    Knowing the population size of a species of wildlife is essential for the design and implementation of management and conservation strategies. Among the methods available for the study of this demographic parameter, the spatially explicit capture-recapture models They have developed considerably in recent years thanks -among other things- to the use of automatic detection devices, such as camera traps.

    However, these advances based on camera trapping have occurred in the study of species in which it is possible to individualize the specimens that are part of a population based on a unique and exclusive pattern of spots on their body, such as the Iberian lynx (lynx pardinus), For example. So far, the implementation of spatially explicit capture-recapture models for the demographic study of animal species without any pattern of spots or other characteristics that allow individual recognition, it has been a challenge.

    When the species under study is not easily recognizable by its natural characteristics, in the capture-recapture the use of an "artificial" marking is very frequent for the recognition of individuals, which must also be permanent during the study period, which means that the animal cannot remove these marks. This marking, if it is intended to be carried out on a large scale, is excessively invasive.

    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 University of Malaga, the Centro de Investigacão em Biodiversidade e Recursos Geneticos (CIBIO, Portugal) and the University of Córdoba, have used the population of marten (tuesday foina) of the Cabañeros National Park as a study model, to develop an integrated method that combines spatial capture-recapture data with individual identification, using tagging with transponders (chips, without identification errors, and without possibility of loss) and recaptures in a small trapping area; GPS data to know the movement of the animals, and a sampling of occupation (presence/absence) in a large surrounding area, using camera traps.

     

    The marten is a medium-sized carnivorous mammal, belonging to the mustelid family, with a more or less regular distribution within the Iberian Peninsula, being capable of occupying a wide variety of habitats.

    The results show that This integrated method achieves much more accurate population density estimates, reducing discomfort to the animals and the costs of field work.. Specifically, the precision improvement of the integrated model is 37% when compared to the application of the spatial capture-recapture estimate alone. In the case study of the stone marten in the Cabañeros National Park, the estimated density with the integrated model is 0.352 (SD: 0.081) individuals/km2.

    The integrated model developed in this study has great potential to provide accurate population density estimates for animal species that cannot be easily distinguished individually., considerably limiting the need to apply invasive and annoying methods for the target fauna of study.

    The scientific publication of this research is available at: