Rapid expansion of Spanish sparrow Passer hispanoliensis north of the Ebro River

Abstract We compile the information available for Spanish Sparrow (Passer hispaniolensis) in the provinces of Navarra and Huesca (northern Spain) until 2022 and add the results of specific censuses carried out in the spring of 2023. It is confirmed that the presence of this species in the area was practically anecdotal, with only 5 records in the last 20 years, and that in 2023 there was a sudden expansion towards the north, with more than 120 records recorded in the area, nesting proven in 17 points and detection of a communal roost far from all of them and probably linked to another colony of unknown location. 82.35% of the colonies were located a few meters from a raptor (Milvus milvus, M. migrans, Aquila chrysaetos and Accipiter gentilis)(11 colonies) or White Stork (Ciconia ciconia)(3 colonies) nest and in all cases there was also House Sparrows (Passer domesticus). The average size of each colony was 3.24 pairs (min-max 1–14) and the nests were at an average height of 11.18 m (min-max 6–18 m) and always in a trees (Pinus halepensis, Populus sp. and Sequoia sempervirens). The role of this species as indicator of climate change is discussed.