Open source evaluation of kilometric indexes of abundance

a r t i c l e i n f o Keywords: KAI GIS GRASS Free and Open Source Wildlife monitoring Mountain hare Kilometric Abundance Index (KAI) is a common measure used in wildlife studies because it allows a straightforward comparison of species abundance in different sites or at different times. KAI expresses the ratio of the total number of individuals (or of signs of presence) observed along a transect by the total transect length covered at each site. v.transect.kia is a new tool for GRASS GIS, developed for automating the evaluation of KAI, reducing the risk of manual errors especially when handling large datasets. It can also split the transects according to one environmental variable (typically habitat type) and evaluate true 3D transect length. It calculates KAI using a point map of sightings and saves the results in the attribute table, the output can be displayed in any GIS or used for further statistical analysis. The tool has been tested on field data from Northern Italy for mountain hare (Lepus timidus), allowing a first wide-area estimate. The Kilometric Index of Abundance (KAI or KI, Eq. (1)) is a common measure used in wildlife studies because it allows a straightforward comparison of species abundance in different sites or at different times (Buckland et al., 1993; Vincent et al., 1991). The presence of one species in a site can be confirmed by direct sightings of the animals or by the signs of their passage that can be reliability detected by a trained field biologist: footprints, tracks, droppings, feeding marks, dens, nests, hairs or feathers as well as carcasses or body parts. These indirect signs of presence are very useful when dealing with elusive species that are difficult to spot or capture. KAI expresses the ratio of the total number of individuals (or of signs of presence) observed along a transect by the total transect length covered at each site. KAI ¼ Number of presence sightings or signs Transect length covered ðkmÞ ð1Þ Line transects surveys have the advantage of being a simple method to implement, they require limited equipment (basically, a GPS receiver) and a limited number of operators compared to other census techniques, thus resulting less expensive and offering the practicality, sensitivity and robustness, " desirable qualities " discussed in Engeman(2005). The method has been designed and is mainly used for vertebrate species (de Thoisy et al. but it can …