Modelling the impact of helminth parasite on rock partridge population dynamics

The aim of this work was to explore the e ect of helminth parasites on the population dynamics of rock partridge (Alectoris graeca saxatilis) that is an endangered species in the Dolomitic Alps (northern Italy). Specifcally, we investigated the hypothesis that the nematode parasite Ascaridia compar can drive population cycles in rock partridge dynamics. In order to support this hypothesis, we compared the predictions obtained from a host-macroparasite interaction model with multi-annual empirical data of A. compar infection in natural host populations. Furthermore, held data suggest a potential interactions through competition between rock partridge and black grouse (Tetrao tetrix) that share a common spatial domain in the Alps. We hypothesized two possible interaction mechanisms: direct competition and parasite-mediated competition, also called apparent competition, and we used mathematical models as a proof-of-principle verification of these hypotheses. Outputs from the direct competition model are in contrast with held observations, while outputs of the parasite-mediated competition model qualitatively at the observed pattern suggesting that the sharing of parasite free-living stages between the two species can trigger the competition playing an important role in the decline of rock partridge in Trentino region.