A new spatial capture-recapture method allows incorporating de-identified samples into population density estimates

    An international group of researchers has developed a new extension of spatially explicit capture-recapture methods that allows working with data from unidentified specimens to improve population density estimates.


    Spatially Explicit Capture-Recapture It is based on the individual identification of wild animals with various sampling techniques –such as photo trapping or genetic identification using non-invasive samples such as feces or hair– and the use of spatial information, allowing density estimates and diverse demographic information to be obtained from very useful in terms of management and conservation.

    One of the problems faced by these methods is that, usually, a part of the samples does not allow identification for various reasons. This is the case of blurred camera trap images or stool or hair samples that, for some reason, do not allow DNA extraction.

    But a New method developed by scientists from Instituto de Investigación en Recursos Cinegéticos (IREC – CSIC, UCLM, JCCM), from the US Geological Survey, NOAA National Marine Fisheries Service and the Warnell School of Forestry and Natural Resources of the University of Georgia (United States), allows the use of all the information, both from identified and unidentified samples, thus increasing the precision of the population density estimates.

     

    The authors have used the brown bear (Ursus arctos) from the Cantabrian Mountains (northern Spain) as a study model (Photo: Jonathan Rodríguez-Ramiro).

    The first signatory of the study, the Dr. Jose Jimenez, researcher at the Higher Council for Scientific Research (CSIC) and member of the Research Group in Game Resources and Wildlife Management of IREC, has indicated that "this improvement is more important in populations of species that are found in low density, and when unidentified samples represent a high percentage of the total”. In extreme cases, with 10% of animals identified, the improvement in precision achieved with this method is almost 80%.

    The authors of this research paper have used the population density estimate of the brown bear as a case study (Ursus arctos) in the Eastern zone of the Cantabrian Mountains, in northern Spain, where they have obtained a density of 1.019 bears/100 km2, with an increase in precision greater than 10% compared to other previous estimates.

    You can consult the scientific publication of this research work, which has been partially financed by the Ministry for Ecological Transition (MITECO) of the Government of Spain, at: