Knowing causes of mortality of biodiversity, especially of rare and endangered species, is of utmost importance to develop effective conservation plans. In France, there is a program to survey mortality and identify causes of death in some endangered raptor species (SAGIR Network), and the Ligue pour la Protection des Oiseaux (LPO) also coordinates a network of volunteers, public institutions (National Parks, National Game and Wildlife Agency, National Forestry Agency), local nature protection and hunting associations, etc. to monitor avian scavenger populations (vultures and red kites) in the French Pyrenean Mountains, which host a high proportion of the French populations of those species.
Through both these networks, many birds are found dead each year, and sent for post-mortems in certified labs. In a recent paper (see below), Philippe Berny & colleagues have analysed the cause of death for 170 scavenger birds found dead in the French Pyrenees over a 7 year period (2005-2012). All birds found dead were submitted to full necropsy, X-Ray, parasitological and toxicology screenings (cholinesterase inhibitors, anticoagulant rodenticides, organochlorine insecticides, heavy metals, including lead). In total 8 Bearded Vultures, 120 Griffon Vultures, 8 Egyptian Vultures and 34 Red Kites were collected and analysed.
Poisoning was by far the most common cause of death (24.1%), followed by trauma/fall (12%), bacterial diseases and starvation (8%) and electrocution (6%). Illegal use of banned pesticides was responsible for most of the cases of poisoning (53% of all poisoning cases) but lead poisoning was also important (17% of all poisoning cases).
Lead isotopic signature could be associated primarily with hunting ammunition – resulting from scavengers eating corpses of animals that had been shot at by hunters. Further, lead poisoning was also associated with trauma, indicating that lead could be a significant contributor to different causes of death.
These results urge for the continuation of the anti-poisoning programmes, more enforcement and criminal offences related to the illegal use of banned pesticides to kill wildlife, and also suggest that severe restrictions on the use of lead ammunition should be introduced.
You can download the full paper below