Past avifaunal assemblages as proxies of terrestrial ecosystem evolution in response to Pleistocene climate oscillations.

Current Western Palearctic avifauna is reported in the fossil record since the EarlyPleistocene. Bird species have specific needs concerning the habitat, especially interms of vegetation, and are very sensitive to habitat changes. Hence, changes incomposition of avifaunal assemblages can reflect habitat patchiness and evolution of thelandscape through time (especially vegetation features) in response to past climaticoscillations. We present the systematic and taphonomic analysis of the bird fossil remains from thelate MIS 3 of two cave deposits in North-Eastern Italy. Buso Doppio del Broion Cave(Vicenza) is located in the Berici Hills, at 150 meters above sea level (m.a.s.l.), while RioSecco Cave (Pordenone) is situated in the Eastern Carnic Pre-Alps, at 580 m.a.s.l. The twosites provided more than 50 species, all belonging to the extant Western Palearctic avifauna.The ecological requirements of the bird species recovered, suggest the presence of a mosaicof different habitats in the surroundings of the caves during the late MIS 3, representedby open areas like steppe, grasslands and shrublands; conifer or mixed forests;rocky cliffs and wetlands. Within the sedimentary succession of the Buso DoppioCave, the upward increase of bird taxa typical of open environments hints to theexpansion of open areas (e.g., grassland and steppe) in response to the ensuing climatedeterioration related to the onset of the Last Glacial Maximum (MIS 2). Furthermore,in the Buso Doppio Cave deposits the presence of two boreal species currentlyabsent from the Italian avifauna (i.e., Bubo scandiacus and Surnia ulula), along withLagopus mutus, Lyrurus tetrix, Tetrao urogallus, Pyrrhocorax graculus, Pyrrhocoraxpyrrhocorax and Prunella collaris at low heights, represent clear indication of aclimate colder than the present one. This paleoenvironmental and paleoclimaticframework completely agrees with the vegetational profile given by the pollen records ofthe Fimon lake deposits (less than 5 km away from Buso Doppio Cave) and ofthe Azzano Decimo core, in the Friulian Plain (about 40 km south of Rio SeccoCave). This work also provided the first Italian fossil record of two species, Troglodytestroglodytes and Phoenicurus ochruros, and the second Italian Pleistocene fossil record ofSurnia ulula. The taphonomic analysis of the fossil remains detected the contribution ofnocturnal raptors, carnivores and, to a lesser extent, Paleolithic hunter-gatherers groups, in theaccumulation of the bird remains. [ABSTRACT FROM AUTHOR]