Il rischio di saturnismo negli uccelli necrofagi in relazione alle attuali modalità di caccia degli ungulati

Summary Wildlife may be exposed to lead contamination as a consequence of hunting activities. Waterfowls and grouses may directly assume lead from the ground (primary assumption), while in raptors lead intoxication may be due to the ingestion of preys with elevated lead concentrations in their tissues (secondary assumption). Recent studies demonstrated that viscera of shot ungulates are quite often directly contaminated with lead due to bullet fragmentation after the shot. If released on the ground, viscera represent a threat for scavenger species. In Europe, saturnism in birds of prey has been quite rarely described and some reports are available for large raptors as griffon vulture Gyps fulvus, golden eagle Aquila chrysaetos and bearded vulture Gypaetus barbatus. In the Alps this problem affects the abundant population of golden eagle and the recently re-introduced population of bearded vulture that is still considered as vulnerable. For the bearded vulture two cases of lead intoxication have already been described in dispersing juveniles. The most viable nucleus of bearded vultures is distributed in the central Alps, between Italy and Switzerland and is characterized by the highest reproductive rates. Hunting management of ungulates is here commonly performed with lead ammunition. The practice of leaving on the ground the ungulate viscera after the shot is still frequent. Hunting season partially overlaps with the most limiting season, in terms of food availability, for birds. The extraordinary conservation value of this bearded vulture population led the Stelvio National Park and the Sondrio Province to implement a study for monitoring the potential risk of lead intoxication for raptors tied to the practice of ungulate viscera deposition after the shot. The viscera of 153 ungulates shot in the Sondrio Province during hunting season 2009-2010 have been collected and examined to detect and quantify lead presence. Information regarding the hunted animal, the type of ammunition, the condition and the outcome of the shot have been collected as ancillary data. Lead fragments in the samples have been investigated through CAT (computed axial tomography) and digital radiography and subsequently manually collected. Overall, in 62.1% of samples lead fragments have been detected. Preliminary results refer to a partial sample of 147 viscera of roe deer, red deer, chamois, wild boar and mouflon. Higher frequencies have been recorded in roe deer (77.7%), chamois (69.6%) while lower in red deer (50%). The highest frequencies of lead in viscera have been detected in ungulates shot in the thorax or in the thigh and hind parts. These first preliminary outcomes confirm the high risk of lead intoxication for large raptors in areas where ungulates are commonly hunted and demonstrate the need of more sustainable hunting practices as the substitution of lead ammunition with non-toxic bullets or concealing under the ground the viscera of the shot ungulates.