PhD in Biological Sciences and Applied Biotechnologies

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Phd thesis

Human presence at high altitude modifies alpine ecosystems. Recreational activities influence species through habitat degradation or loss, but human presence means also food provisioning, thus modifying the availability of resources. We aim here to highlight trophic ecology and responses of the Alpine Chough to human activities. Regarding the species responses, the first study was realized in two Alpine areas differing in human disturbance; human presence led to shorter stay times and reduced intake rates, thus potentially negatively influencing foraging behaviour. However, habituation in the tourist site could enhance feeding success. The second study analyzes the factors affecting flock movements during winter in three tourist sites in the Alps; temperature and people may influence bird activities, with lower temperature and higher number of people resulting in higher presence and larger flock size. However, these relationships differed among sites, with the site with the largest flock size showing much weaker relationships. Regarding Alpine Chough trophic ecology, the first study aimed to verify whether the spatio-temporal distribution of birds was similar to the one of grasshoppers (i.e. their key prey in the Alps during the summer); results showed that flock size can respond to prey abundance and biomass, and this result indicates that choughs can follow large scale fluctuation of the most abundant food item despite being generalists. Finally, the diet of the Alpine Chough in two study areas is analyzed with DNA barcoding (to identify fruit from seeds in winter diet) and DNA metabarcoding (to characterize summer diet), while stable isotope ratios analysis can indicate which population has the most diverse diet. Preliminary results show a higher diet variability in the tourist site population, where discarded food is available. In conclusion, the first part of the project demonstrates that Alpine Chough can potentially develop habituation to human presence enhancing the foraging success. However, when habituation is not present human presence is immediately perceived as disturbance and the foraging efficiency decreases. The second part of the project confirmed that grasshoppers can be all important during the summer for chough diet. However, the high variability found in the diet of the population belonging to the tourist site, demonstrates that they can exploit other food items. The Alpine Chough results being an extremely adaptive species, however, populations which lives in undisturbed sites can be negatively impacted, and some gaps relative to the effect of human food on the species are present. Future studies could be oriented to evaluate individual conditions in populations which exploit anthropogenic food, and to consequently propose tourist area management guidelines.