• Eurasian stone-curlew
• foraging behaviour
• migration
• movement ecology
• non-breeding period

Movement is a critical component of animal biology, affecting individual fitness and survival and playing an important role in structuring populations and the functioning of ecosystems. Among the different types of movement, migration and foraging movements play an essential role in bird biology. Both types of movements show great variability at species, population and individual level.
For what concern migratory behaviour, short-distance migrants for example often adopt a partial migratory strategy and tend to have a flexible migration schedule that allows a more effective response to extreme environmental variations. Weather seasonality and environmental heterogeneity have been reported as significant factors in the diversification of migratory behaviour for Mediterranean migrants, but relatively few studies investigated the migration patterns of non-passerine birds migrating within this area.
Foraging movements occur generally at smaller scale, but like migration they show high variability in patterns that may change between and within individuals even belonging to the same population.
External factors such as food supply and habitat structure can influence the variability of foraging behaviour and the agricultural ecosystem, where habitat modifications act at different temporal and spatial scales, is a good setting to study this topic. In Europe, intensive farming practices were reported as the main factors in changing of foraging behaviour in farmland species due to the loss of suitable areas during the breeding period, but relatively few studies investigated the spatial behaviour during the non-breeding period.
Understanding the factors that influence animal movements at different spatial and temporal scales is crucial in the study of movement ecology, especially because it can allow us to predict how animals will respond to changes in environmental conditions.
In this dissertation, I focused on the factors affecting the spatial behaviour of the Eurasian Stone-curlew Burhinus oedicnemus, a short distance migrant inhabiting the European agricultural landscape, during the non-breeding
In chapter 2 I studied the migratory strategy of 40 individuals tagged with geolocators and GPS-GSM tags during the period 2010-2019 and belonging to continental and Mediterranean populations of the Italian peninsula. The proportion of migrants turned out to be higher in continental populations, but I observed a significant variability also within Mediterranean populations. All birds spent the winter within the Mediterranean basin. Continental Stone-curlews departed earlier in spring and later in autumn and covered longer distances than those from Mediterranean areas. The speed of migration did not change between seasons for continental birds, while Mediterranean individuals migrated faster in spring. The likelihood of departure for autumn migration of GPS-tagged birds increased when temperatures were near or below 0 °C suggesting that Stone-curlews tend to delay departure until weather conditions worsen abruptly. As a consequence of global warming in the Mediterranean, I suggest that the frequency of migratory birds in the considered populations might decrease in the near future. This could affect the distribution of species throughout the year and should be taken into account when targeting conservation measures.
In chapter 3 I compared the roosting and foraging behaviour during the pre-migratory and the wintering periods (years 2013-2021) of 28 GPS-tagged Stone-curlews belonging to two populations (Piave and Maremma) living in rather different ecological contexts due to different predominant agricultural practices. In Maremma, Stone-curlews tended to change roost site more frequently than in the Piave area, at least in winter, perhaps because of the greater hunting disturbance. The wide distribution of roost sites in Maremma suggested that there was a high availability of suitable sites in the area, which could at least partially compensate for the effect of disturbance. In both areas the Stone-curlews foraged near the roost site early in the season and then sought feeding areas further afield, perhaps in response to the depletion of resources near the roost sites. The distances travelled in winter were greater than those recorded in the pre-migratory period in both areas. The size of individual foraging areas tended to be larger in the Piave area in both periods, suggesting that food availability was lower in the former possibly due to the dominance of the intensive agricultural practices. This is further suggested by the low degree of overlap between foraging areas used on consecutive nights record in Piave. In conclusion, the collected data indicated that during the non-breeding period the Stone-curlew shows a noticeable degree of ecological and behavioural flexibility that allows the species to exploit different habitat types, including those with a significant degree of intensification of agricultural practices. However, the presence of natural habitats and/or extensive cultivation seems essential to buffer the effect of intensive farming practices and ensure the conservation of the Stone-curlew and possibly of other farmland species.
Finally, in chapter 4 I investigated the environmental factors affecting the selection of winter roost and foraging sites of the Stone-curlew in the Grosseto province (Central Italy). To this aim, annual surveys of 24-36 potential roost sites, carried out in the period 2013-2020, were integrated with tracking data collected on eight birds equipped with GPS tags in the period 2013-2017. Roost occurrence probability turned out to be higher in flat terrain but was negatively affected by olive groves cover and road density, a proxy of human disturbance. Other land cover types did not exert a significant effect on roost occurrence probability, but, together with vegetation height, significantly affected roost size. In particular, the highest number of roosting individuals was found in fallows with short vegetation heights (< 5 cm). Contrary to what was observed for roost sites, olive groves were significantly selected by birds during foraging. The use of livestock to control the vegetation cover in traditional olive groves seems to be a disturbing factor during the day, but their grazing activity and the attractive effect of their droppings for invertebrates could favor the foraging activity of the Stone-curlew. In addition to olive groves, birds used a variety of agricultural habitats and showed considerable inter-individual variability in their preferences. These specializations for particular habitats could be an important factor for winter survival, as could help to optimize foraging movements and to reduce competition. The mosaic of different habitats recorded in the province of Grosseto, where extensive agricultural practices are still relatively widespread, could be a critical factor for wintering Stone-curlews. Preserving this heterogeneity is probably fundamental for the conservation of this species in the area.
In conclusion, this dissertation focused on the factors affecting the spatial behaviour of the Eurasian Stone-curlew, Burhinus oedicnemus, that could be relevant to predict the future distribution of the species that live in a context as the Western Palearctic, area characterized by a strong effect of climate change and land-use modification.