Toward reliable population estimates of wolves by combining spatial capture-recapture models and non-invasive DNA monitoring.

Decision-makers in wildlife policy require reliable population size estimates to justify interventions, to build acceptance and support in their decisions and, ultimately, to build trust in managing authorities. Traditional capture-recapture approaches present two main shortcomings, namely, the uncertainty in defining the effective sampling area, and the spatially-induced heterogeneity in encounter probabilities. These limitations are overcome using spatially explicit capture-recapture approaches (SCR). Using wolves as case study, and non-invasive DNA monitoring (faeces), we implemented a SCR with a Poisson observation model in a single survey to estimate wolf density and population size, and identify the locations of individual activity centres, in NW Iberia over 4,378 km2. During the breeding period, posterior mean wolf density was 2.55 wolves/100 km2 (95%BCI = 1.87-3.51), and the posterior mean population size was 111.6 ± 18.8 wolves (95%BCI = 81.8-153.6). From simulation studies, addressing different scenarios of non-independence and spatial aggregation of individuals, we only found a slight underestimation in population size estimates, supporting the reliability of SCR for social species. The strategy used here (DNA monitoring combined with SCR) may be a cost-effective way to generate reliable population estimates for large carnivores at regional scales, especially for endangered species or populations under game management.

Spatial assessment of wolf-dog hybridization in a single breeding period.

Understanding the dynamics of wolf-dog hybridization and delineating evidence-based conservation strategies requires information on the spatial extent of wolf-dog hybridization in real-time, which remains largely unknown. We collected 332 wolf-like scats over ca. 5,000km2 in the NW Iberian Peninsula to evaluate wolf-dog hybridization at population level in a single breeding/pup-rearing season. Mitochondrial DNA (MtDNA) and 18 ancestry informative markers were used for species and individual identification, and to detect wolf-dog hybrids. Genetic relatedness was assessed between hybrids and wolves. We identified 130 genotypes, including 67 wolves and 7 hybrids. Three of the hybrids were backcrosses to dog whereas the others were backcrosses to wolf, the latter accounting for a 5.6% rate of introgression into the wolf population. Our results show a previously undocumented scenario of multiple and widespread wolf-dog hybridization events at the population level. However, there is a clear maintenance of wolf genetic identity, as evidenced by the sharp genetic identification of pure individuals, suggesting the resilience of wolf populations to a small amount of hybridization. We consider that real-time population level assessments of hybridization provide a new perspective into the debate on wolf conservation, with particular focus on current management guidelines applied in wolf-dog hybridization events.

Diferencias del sexo y de la edad en el contenido de metales pesados (Cd, Cu, Pb y Zn) en pelos de lobo ibérico (Canis lupus signatus) del Norte de España / Sex and age differences in heavy metals content (Cd, Cu, Pb and Zn) in hairs of Iberian wolf (Canis lupus signatus) from the North of Spain

Como consumidor situado en la cumbre de las cadenas alimenticias, el lobo ibérico (Canis lupus signatus) puede sufrir fenómenos de bioacumulación de diferentes contaminantes que se encuentran distribuidos en el medio ambiente. Esto permite pensar en su posible empleo para detectar y evaluar los efectos toxicológicos de xenobióticos diversos como los metales pesados en los ecosistemas terrestres, pudiendo por ello llegar a ser considerado como adecuado biomonitor del medio. Sin embargo, debido a su importancia ecológica, los métodos destructivos no son los más adecuados para dicha determinación toxicológica, de modo que las muestras no destructivas cobran gran importancia como herramienta para dicha biomonitorización. En el presente trabajo se ha determinado la influencia del sexo y de la edad en la concentración de Cd, Cu, Pb y Zn en pelo de lobos procedente del noroeste de España. Las muestras de pelo (n = 158) fueron lavadas y tras ser sometidas a una digestión por vía húmeda, las concentraciones de Cd, Cu, Pb y Zn fueron determinadas mediante Voltamperometría de Disolución Anódica. Con respecto a la variable sexo, las concentraciones más altas de todos los metales pesados estudiados se cuantificaron en el pelo de las hembras, coincidiendo con lo observado por otros autores, lo cual puede estar asociado a las diferencias fisiológicas y a los diferentes hábitos nutricionales. No obstante, sólo se observaron diferencias estadísticamente significativas para un nivel de significación 0,05 en el caso del cobre, acumulándose más en las hembras que en los machos. Respecto a la variable edad, no se observó un patrón de acumulación de estos metales bien definido. Las concentraciones de Cd y Zn fueron superiores en los individuos cachorros (< 1 año) mientras que las de Cu y Pb resultaron más altas en los jóvenes (entre 1 y 2 años). En todos los casos, los niveles cuantificados pueden ser considerados indicativos de unas concentraciones relativamente bajas, sin relevancia ecotoxicológica y no constituyendo un factor medioambiental serio que pueda afectar a la supervivencia de la población considerada (AU)

As top consumers in food chains, the Iberian wolves (Canis lupus signatus) might experiment bioaccumulation of contaminants which are distributed in the environment, thus offering opportunities to detect and assess the toxicological effects of xenobiotics like the heavy metals on terrestrial ecosystems and to use this species as an adequate bioindicator within the environmental biomonitoring programs. Notwithstanding, destructive methods are not acceptable for those ecotoxicological purposes, thus rendering non-destructive samples as the most important tools for such biomonitoring. At the present study the sex and age influence on Cd, Cu, Pb and Zn concentration in hair of wolves from NW Spain has been determined. Hair samples (n=158) were washed and after wet digestion, Cd, Cu, Pb and Zn concentrations were measured by Anodic Stripping Voltammetry. With respect to sex, the highest concentrations of all heavy metals were quantified on female's hair, similarly to that observed by other authors, which could be associated to different physiological characteristics and nutritional habits. Nevertheless, statistically differences with a significant level of 0.05 were only observed in the case of the copper, being higher in female than in males. With respect to age, there was not a well-defined accumulation standard of the studied heavy metals. The Cd and Zn concentrations were higher in wolf cubs (< 1 year), meanwhile the Cu and Pb concentrations were higher in the young ones (between 1 and 2 years). In all cases, the quantified metal amounts could be considered as indicative of low contaminations levels, with no ecotoxicological concern, and not constituting a serious environmental factor affecting the survival of the considered populations (AU)

Helminths in the wolf, Canis lupus, from north-western Spain.

Fifteen helminth species were collected from 47 wolves (Canis lupus ) which were surveyed from 1993 to 1999 in northwestern Spain. These included the trematode Alaria alata (2.1%); the cestodes Taenia hydatigena (44.7%), T. multiceps (29.8%), T. serialis (2.1%), Dipylidium caninum (6.4%) and Mesocestoides sp. aff. litteratus (4.2%); and the nematodes Pearsonema plica (7.4%), Trichuris vulpis (10.6%), Trichinella britovi (12.8%), Ancylostoma caninum (8.5%), Uncinaria stenocephala (51.1%), Toxocara canis (6.4%) Toxascaris leonina (4.2%), Angiostrongylus vasorum (2.1%) and Dirofilaria immitis (2.1%). Only two wolves were not infected. A single infection occurred in 28.9% of the cases, but the commonest infracommunity (31.1%) involved three species. The helminths Alaria alata, Taenia hydatigena, Mesocestoides sp. aff. litteratus, P. plica, Trichuris vulpis, and Ancylostoma caninum parasitizing C. lupus are reported for the first time in Spain. Taenia serialis and D. immitis are reported for the first time in wolves in Europe. Angiostrongylus vasorum represents a new host record for wolves. The helminth fauna of Spanish wolves is compared with that of other European wolf populations. Some epidemiological considerations of the helminth fauna of wolves in Spain and the health risk to humans are also discussed.