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An experiment by Wobeser & Wobeser (1992) highlighted the difficulties associated with detecting dead animals in the field in an experiment. They placed a total of 250 dead chicks in a one ha area over a 5-day period (50 chicks/day) and 10 % of the area were searched daily for 10 days. Only two intact chicks that had been in place for longer than 24 hours were recovered while only three times a scavenger was observed preying on a chick. This clearly shows that, especially in smaller animals, detection of most cases (regardless of cause of death) is often unlikely. The main reasons being removal of carcass by scavengers, advanced decay and removal of illegally killed wildlife by the perpetrator. In our experience, the willingness of, e.g., hunters to report suspicious deaths of wildlife increases with mutual reliance of involved authorities and their professional attitude. If a wildlife crime is suspected but no carcass has been spotted or wildlife crimes happen regularly in a certain region, a number of actions may be proposed to help detecting dead wildlife: • Raising public awareness (via press releases and social media activities by authorities or NGOs) is useful when wildlife crimes happen on a regular basis in a distinct area. 14 Locals that use the area for outdoor activities may be of help when asked to watch for any suspicious dead wildlife. • A passive or active targeted surveillance program may be implemented with members of stakeholders (NGOs, local hunting association) searching defined areas on a regular basis. • Search dogs are especially useful and several countries (e.g. Spain, Hungary, Czech and Slovak Republic) now have dogs specially trained for detecting poisoned birds of prey. The dogs may be privately owned and trained at the expense of NGOs or dedicated police dogs. 15 3 CAUSES OF DEATH IN WILDLIFE Death of wildlife can be the result of many different causes, illegal human activities being only a very small proportion of it fortunately. It is the basic task of wildlife forensic investigations to rule out natural causes of death and possibly confirm illegal killing. Basically, death of wildlife can be attributed to natural and non-natural, human induced, causes. These can be refined into subcategories: • Natural o Disease o Starvation/decrepitude o Predation o Intra-/interspecific fights o Ingestion of toxic plants o Natural Disasters: Avalanches, landslides, flooding, thunderstorms, forest fires, lightning strikes, etc. o …. • Non-natural o Human induced „legal“ causes − Legal hunting − Collisions with vehicles, trains, aircraft, windmills, power lines − Electrocution o Human induced “illegal” causes − Illegal Shooting/Trapping − Poisoning (incl. secondary Poisoning) While some of the causes are more or less apparent (e.g. a bird stuck into the fuselage after colliding with an airplane), many others are by far less obvious. 16 3.1 Natural causes 3.1.1 Disease Diseases caused by infectious agents as a cause of death in wildlife are far more widespread than most expect. The outbreak of a certain disease and subsequent death may be limited to a single animal or to a few cases in a confined area, but may also develop to an epidemic, affecting animal populations in large regions. When occurring as epidemics, diseases may play a significant role in the population ecology of the affected species and may have detrimental effects on it. These episodes do occur in Europe and the Alpine Region as well, examples being e.g. scabies (a skin disease caused by mites) in alpine chamois (Rupicapra rupicapra), infectious keratoconjunctivitis (an ocular disease caused by bacteria) in alpine chamois and alpine ibex (Capra ibex), tuberculosis in red deer (Cervus elaphus) in some parts of the Alpine Region, the reoccurring of the viral disease avian influenza in many parts of Europe every now and then, the present outbreak of African swine fever in wild boars (Sus scrofa) in parts of Europe, rabies in various carnivores that fortunately was eradicated in central Europe just recently, and others. Research and knowledge on wildlife disease has dramatically increased in the last decades, partly due to concerns over possible spill-overs to domestic animals (which has occurred) and even humans (so called zoonotic diseases). Experts and dedicated institutions dealing with wildlife diseases are found in many countries nowadays. However, only few countries have long-term surveillance programs on diseases in wildlife and hence knowledge on the occurrence of distinct diseases still remains not comprehensive. Non-infectious diseases (e.g. cancer, bone fractures) do occur in wildlife as well, but seem to play a minor role as causes of death compared to infectious ones. Due to possible debilitation and weakness of the diseased animals, some of them (depending on species) will be prayed on by predators before they die of the disease. Nevertheless, chances are high that a wild animal found dead has died of a specific or non-specific disease. As with other causes of death in wildlife, this can only be confirmed or ruled out by a thorough necropsy of the carcass at dedicated institutions and ancillary investigations. 17 3.1.2 Starvation/decrepitude Starvation and emaciation of wild animals is commonly encountered under certain circumstances. The reasons encompass unfavourable environmental conditions (e.g. snow cover), species overpopulation, lack of food, (chronic) disease, inability of food intake because of disease or injury amongst others. During necropsy, starvation is easily recognisable by lack of fat tissue. Decrepitude may be hard to define in wildlife since the ultimate cause of death in this status may be chronic disease or starvation due to inability of food intake. 3.1.3 Predation Predation by carnivorous animals is a common natural process. Although the “target” species of this handbook (large carnivores, birds of prey) are less likely to be preyed upon, predation should always be considered as a possible cause of death when investigating a carcass. 3.1.4 Intra-/interspecific fights The reasons for intra- and interspecific fights are manifold, including fighting over territories, partners and food sources. The majority of these fights are non-lethal, but deaths may occur. Signs for fights