Human-mediated global change will probably increase the rates of natural hybridization and genetic introgression between closely related species, and this will have major implications for conservation of the taxa involved. In this study, we analyse both mitochondrial and nuclear data to characterize ongoing hybridization and genetic introgression between two sympatric sister species of mustelids, the endangered European mink (Mustela lutreola) and the more abundant polecat (M. putorius). A total of 317 European mink, 114 polecats and 15 putative hybrid individuals were collected from different localities in Europe and genotyped with 13 microsatellite nuclear markers. Recently developed Bayesian methods for assigning individuals to populations and identifying admixture proportions were applied to the genetic data. To identify the direction of hybridization, we additionally sequenced mtDNA and Y chromosomes from 78 individuals and 29 males respectively. We found that both hybridization and genetic introgression occurred at low levels (3% and 0.9% respectively) and indicated that hybridization is asymmetric, as only pure polecat males mate with pure European mink females. Furthermore, backcrossing and genetic introgression was detected only from female first-generation (F1) hybrids of European mink to polecats. This latter result implies that Haldane's rule may apply. Our results suggest that hybridization and genetic introgression between the two species should be considered a rather uncommon event. However, the current low densities of European mink might be changing this trend.

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Human intervention is the main cause of the decline of the Critically Endangered European mink Mustela lutreola. In this study we analysed the main causes of direct human-caused mortality of the species in Spain. A total of 47 mortality records were obtained for the period 1950–1989, and 145 for 1990–2008. There was temporal variation in the cause of death, with trapping and shooting being the most common causes of mortality in 1950–1989 and road-kills in 1990–2008. In the case of road-kills there was variation related to road type. Males were more affected by road-kills than females, especially during the mating season when they range more widely. Our results indicate that there has been a change in human social behaviour and in people's awareness of the species, with a reduction in European mink captured and shot but an increase in mortality on roads.

En este trabajo se desarrolló un protocolo de censo a gran escala para obtener datos actuales de las aves nocturnas y que sirva de base para futuros trabajos. El área de estudio, Euskadi, se dividió en cuadrículas UTM de 5x5 km de las que se escogieron 65 que representaban todos los tipos de vegetación. Dentro de cada cuadrícula se seleccionaron 8 Unidades de Censo (UCs), separadas entre sí por una distancia mínima de 1 km. En cada UC se llevó a cabo un protocolo de censo dividido en tres fases: 5 min de escucha de voces espontáneas, 5 min de reclamo de una sola especie y 5 min de escuchas en silencio, que se repitió mensualmente desde enero hasta julio de 2018. Sólo se utilizó el reclamo de una especie por censo, de acuerdo con los picos anuales específicos de respuesta al reclamo, y únicamente para las estrigiformes. El cárabo común resultó ser la especie más abundante y ampliamente distribuida de Euskadi, siguiéndole bastante lejos la lechuza común, el autillo europeo y el mochuelo europeo; mientras que el búho chico y el búho real fueron escasos y con una distribución localizada, y el búho campestre y el mochuelo boreal resultaron ser especies raras. El chotacabras europeo apareció en el 31,1% de las UCs, mientras