Habitat selection and ontogeny of habitat use by juvenile Eurasian Spoonbill Platalea leucorodia revealed by GPS tracking

Summary Despite the widely recognized value of wetlands in providing vital ecosystem services, these are presently being degraded and ultimately destroyed, leading to a decrease in the biodiversity associated with these areas. Some species inextricably linked to wetlands, however, have been increasing and (re)colonizing areas across their range; a notable example being the Eurasian Spoonbill Platalea leucorodia. In this study we aimed to identify the most important habitats for juvenile spoonbills fledging from a traditional colony in Portugal, located in Ria Formosa, during the period of their life with the lowest survival rates: the first months after leaving the colony. We deployed 16 GPS/GSM tags on juveniles captured in different years (2016 to 2020) and tracked them during post-fledging dispersal and first winter (average 166.4 ± 29.2 SE days). Using Corine Land Cover data, we were able to identify which habitats were most important. Several habitats were used in variable proportions by individuals originating from the same colony, but there was a general trend towards using fewer habitats along the first months of life. Intertidal wetlands were the most used habitat, but anthropogenic habitats such as Wastewater Treatment Plants, saltpans and rice fields were identified as alternative habitats for young spoonbills, and may had contributed to the recent expansion of this species in Portugal.