The purpose of this study was to monitor exposure to lead in four species of raptors in Southeastern Spain (Murcia Region). Samples of liver, kidney, brain, blood, and bone from two species of diurnal raptors (European kestrel (Falco tinnunculus) and European buzzard (Buteo buteo)) and two species of nocturnal raptors (Eagle owl (Bubo bubo) and Little owl (Athene noctua)) were obtained during 1994. Relationships were found between size and age of the birds, the nearness to areas of human activity and lead concentrations in tissues. The lead distribution pattern reveals that the bone is the principle organ for accumulation (0.62-43 mg/Kg, dry weight), followed by the kidney (0.03-0.66 mg/Kg, wet weight), and liver (0. 017-0.05 mg/Kg, w.w.), and to lesser extent, the brain (0.013-0.223 mg/Kg, w.w.). This distribution pattern indicates that raptors in Southeastern Spain were exposed to environmental low lead levels continuously over an extended period of time. Correlations between lead in bone and lead in soft tissues were higher in European buzzards (r = 0.87-0.95) and Eagle owl (r = 0.71-0.86) than those found in European kestrels (r = 0.53-0.58) and Little owls (r << 0). However, correlations between lead concentrations in soft tissues and in blood were high (r = 0.85-0.99).

No abstract

The use of conditioned food aversion (CFA) can reduce the predation conflict and therefore the incidence of illegal poisoning, which is one of the most important conservation threats for predators and scavengers around the world. CFA is a robust learning paradigm that occurs when animals associate a food with a discomfort induced by a chemical, thereby avoiding that food in subsequent encounters. We reviewed the potential of 167 chemical compounds to be used in CFA, considering effects, margin of safety, accessibility, and detectability. After the review, 15 compounds fulfilled the required characteristics, but only five were finally selected to be tested in CFA assays with dogs. Of the tested compounds, thiabendazole, thiram and levamisole caused target food rejection by dogs and reduced the time spent eating during post-conditioning. However, despite being microencapsulated, levamisole appeared to be detectable by dogs, whereas thiram and thiabendazole were not. Fluconazole and fluralaner did not produce any CFA effect. Thiabendazole, thiram and levamisole can therefore induce CFA, and thus are potential candidates as aversive compounds for wildlife management. Thiram is a new undetectable, safe and accessible compound that can induce CFA in canids, and opens new possibilities to develop methods of non-lethal predation control.

Worldwide, predators and humans are in conflict for resources such as game species or livestock, especially in the case of medium-large wild canids. One non-lethal method to reduce predation is conditioned food aversion (CFA), in which animals learn to avoid a food due to the illness after its ingestion, caused by the addition of an undetected chemical compound. Food aversion can be enhanced by adding an artificial odour cue, in a process known as taste-potentiated odour aversion (TPOA). We carried out an experiment on penned dogs with three experimental groups to test CFA and TPOA. We offered the food mixed with a combination of microencapsulated levamisole + vanilla odour (ODO), microencapsulated levamisole (LEV), and plain food as a control. The aims were: a) to test whether dogs are able to detect the microencapsulated levamisole; b) to analyse the strength and extinction of CFA induced by microencapsulated levamisole; c) to analyse the strength and extinction of TPOA. Two-choice tests were carried out during 11 months in the post-conditioning phase, and two reinforcements with microencapsulated levamisole were done during the first month. In the first post-conditioning test, ODO and LEV groups ate significantly less untreated food than control group. After the reinforcement, suddenly the dogs in LEV group started to eat the food. Three of four dogs in ODO group showed longlasting CFA until the 11 th month. These results show that TPOA could be used to induce odour aversion on canids and that the odour cue overshadows the slight bitter taste of microencapsulated levamisole.These results open new possibilities to develop TPOA as tool to reduce predation by wild canids.

Lead intoxication is an important threat to human health and a large number of wildlife species. Animals are exposed to several sources of lead highlighting hunting ammunition and lead that is bioavailable in topsoil. Disentangling the role of each in lead exposure is an important conservation issue, particularly for species potentially affected by lead poisoning, such as vultures. The identification of lead sources in vultures and other species has been classically addressed by means of stable-isotope comparisons, but the extremely varied isotope signatures found in ammunition hinders this identification when it overlaps with topsoil signatures. In addition, assumptions related to the exposure of individual vultures to lead sources have been made without knowledge of the actual feeding grounds exploited by the birds. Here, we combine lead concentration analysis in blood, novel stable isotope approaches to assign the origin of the lead and GPS tracking data to investigate the main foraging grounds of two Iberian griffon vulture populations (N=58) whose foraging ranges differ in terms of topsoil lead concentration and intensity of big game hunting activity. We found that the lead signature in vultures was closer to topsoil than to ammunition, but this similarity decreased significantly in the area with higher big game hunting activity. In addition, attending to the individual home ranges of the tracked birds, models accounting for the intensity of hunting activity better explained the higher blood lead concentration in vultures than topsoil exposure. In spite of that, our finding also show that lead exposure from topsoil is more important than previously thought.