Miguel Delibes-Mateos

Rabbit populations and game management: the situation after 15 years of rabbit haemorrhagic disease in central-southern Spain

Over recent decades wild rabbit populations have undergone a sharp decline in Spain with consequent negative impact both on a game-based economy, and on the conservation of threatened species that depend on rabbits. We investigated the relationships between rabbit population change and habitat and game management in central-southern Spain. To determine recent rabbit population changes we revisited 60 localities during summer 2002 to repeat surveys previously carried out in 1993. Each survey consisted of 4-km walked transects to record indices of rabbit abundance. The percentage of vegetation cover and of different soil types were also estimated during these transects. In the same areas, the type and intensity of game management practices were obtained by interviewing hunting managers, hunters or gamekeepers. Rabbit populations were stable or increasing only in 26.6% of the studied populations, more commonly in areas with soft soils where warren building is easier for rabbits and where rabbits were an important game species and managed to increase their numbers. Although we could not establish causality, habitat management and predator removal were the main management practices related to rabbit population change. Rabbit scarcity in Spain constitutes a serious problem for conservation, so hunters, researchers and policy makers need to reach a consensus to establish a long-term program to monitor rabbit population trends and share results obtained, especially when intense manage programs are being carried out to improve rabbit abundance.

Past, present and future of wild ungulates in relation to changes in land use

In recent decades, Mediterranean landscapes have been experiencing more rapid changes in land use than usual, which have affected the ecology of the species inhabiting this biodiversity hotspot. Some studies have assessed the effect of such changes on biodiversity, but most of these were diachronic studies of population dynamics, or synchronic studies of species habitat selection, whereas few studies have simultaneously taken into account temporal changes in habitat composition and changes in species distribution. This study analysed the effects of land-use changes on the distribution of wild ungulates (Capreolus capreolus, Capra pyrenaica, Cervus elaphus and Sus scrofa). Using favourability function and Markov chain analysis combined with cellular automata, we addressed the following objectives: (i) to examine the environmental determinants of ungulate distribution in the past (1960s) and present (1990s), (ii) to model land use for 2040 to forecast future species distributions and (iii) to assess the biogeographical differences between the above-mentioned study periods (past–present and present–future). Species favourability was predicted to be more widely distributed in the present than in the past, but this increase varied across species. Areas predicted to be favourable in the present should remain stable in the future, but in addition there will be more new favourable areas not previously occupied by these species. The results are discussed from the perspective of the socio-economic relevance of wild ungulates in relation to some unfavourable areas of Mediterranean regions.

Translocations as a risk for the conservation of European wild rabbit Oryctolagus cuniculus lineages

Population units that merit separate management and are of conservation concern have been called evolutionary significant units. Two divergent lineages of the European rabbit Oryctolagus cuniculus occur naturally in Spain, with a well-marked geographical distribution. We analysed the frequency and importance of rabbit translocations in central-southern Spain and whether this practice, carried out by hunters and conservationists, could cause the mixture of two clearly different evolutionary significant units. We carried out interviews in 1993 and 2002 at 60 locations to determine the presence and intensity of translocations during both decades. The distribution of the lineages was obtained using mtDNA analysis of hunted rabbits in 2003-2005. We demonstrate that rabbit translocation was used frequently in the 1980s and increased in the 1990s. Up to 43% of the studied areas translocated rabbits in the latter decade, whereas only 25% did so in the 1980s. Our results show that neither the origin of the introduced rabbits nor their genetic lineage were taken into account in most of the translocations. We found rabbits of lineage A in several localities within the distribution area of lineage B, and vice versa, probably as a consequence of translocations. The distribution of both lineages is likely to have been altered by human activity and this could represent the loss of the results of 2 million years of genetic differentiation with possible attendent ecological consequences. Consequently, authorities should more closely regulate rabbit translocations and convey to both hunters and conservationists the importance of not mixing the lineages by translocations.

Long-Term Changes in Game Species Over a Long Period of Transformation in the Iberian Mediterranean Landscape

Agricultural change has transformed large areas of traditional farming landscapes, leading to important changes in the species community assemblages in most European countries. We suspect that the drastic changes in land-use that have occurred in Andalusia (southern Spain) over recent decades, may have affected the distribution and abundance of game species in this region. This article compares the distribution of the main game species in Andalusia during the 1960s and 1990s, using data from maps available from the Mainland Spanish Fish, Game and National Parks Service and from recent datasets on hunting yield distributions, respectively. Big-game and small-game species were significantly segregated in southern Spain during the 1990s, as two clearly independent chorotypes (groups of species whose abundances are similarly distributed) were obtained from the classification analysis. In contrast, big-game and small-game species were not significantly segregated several decades ago, when there was only one chorotype consisting of small-game species and wild boar. The other three ungulates did not constitute a significant chorotype, as they showed positive correlations with some species in the group mentioned above. These changes seem to be a consequence of the transformations that have occurred in the Iberian Mediterranean landscape over the last few decades. The abandoning of traditional activities, and the consequent formation of dense scrubland and woodland, has led to an expansion of big-game species, and a decrease of small-game species in mountain areas. Moreover, agricultural intensification has apparently depleted small-game species populations in some agricultural areas. On the other hand, the increasingly intensive hunting management could be artificially boosting this segregation between small-game and big-game species. Our results suggest that the conservation and regeneration of traditional agricultural landscapes (like those predominating in the 1960s) should be a priority for the conservation of small-game species.

Feeding responses of the red fox (Vulpes vulpes) to different wild rabbit (Oryctolagus cuniculus) densities: a regional approach

We investigate the feeding responses of the red fox (Vulpes vulpes) at a regional scale to different densities of European wild rabbit (Oryctolagus cuniculus) in central–southern Spain. Rabbit abundance indices were obtained in 86 localities during summer 2002. The diet of the fox was studied by analysis of 114 scats collected in 47 of these localities. The feeding response of the fox was examined by a representation of the dry weight percent of rabbit in the diet as a function of the abundance of rabbits; this used data only from those localities where at least 3 scats were collected (70 fox scats from 18 localities). We evaluated the relationship between rabbit abundance and the diversity of the diet of the fox. The feeding patterns of red foxes approximated to Holling’s type III functional response, typical of opportunistic predators. There was a negative relationship between the diversity of the fox’s diet and the abundance of rabbits. Therefore, the fox apparently behaves as a facultative predator, feeding on rabbits when they are abundant and shifting to other prey (and hence a more diverse diet) when rabbits are scarce. These findings are the first step towards understanding the potential role of red foxes in regulating rabbit populations in central–southern Spain.

New directions in management strategy evaluation through cross-fertilization between fisheries science and terrestrial conservation

On 1 and 2 June 2010, an international meeting was held at the University of Paris Sud XI, France, organized within the framework of the EU FP7 consortium project HUNT, to bring together fisheries and conservation scientists to discuss a unified framework for the future of management strategies for harvested species.

Reduced introgression of the Y chromosome between subspecies of the European rabbit (Oryctolagus cuniculus) in the Iberian Peninsula

The role of the Y chromosome in speciation is unclear. Hybrid zones provide natural arenas for studying speciation, as differential introgression of markers may reveal selection acting against incompatibilities. Two subspecies of the European rabbit (Oryctolagus cuniculus) form a hybrid zone in the Iberian Peninsula. Previous work on mitochondrial DNA (mtDNA), Y‐ and X‐linked loci revealed the existence of two divergent lineages in the rabbit genome and that these lineages are largely subspecies‐specific for mtDNA and two X‐linked loci. Here we investigated the geographic distribution of the two Y chromosome lineages by genotyping two diagnostic single nucleotide polymorphisms in a sample of 353 male rabbits representing both subspecies, and found that Y chromosome lineages are also largely subspecies‐specific. We then sequenced three autosomal loci and discovered considerable variation in levels of differentiation at these loci. Finally, we compared estimates of population differentiation between rabbit subspecies at 26 markers and found a surprising bimodal distribution of FST values. The vast majority of loci showed little or no differentiation between rabbit subspecies while a few loci, including the SRY gene, showed little or no introgression across the hybrid zone. Estimates of population differentiation for the Y chromosome were surprisingly high given that there is male‐biased dispersal in rabbits. Taken together, these data indicate that there is a clear dichotomy in the rabbit genome and that some loci remain highly differentiated despite extensive gene flow following secondary contact.

Ecosystem Effects of Variant Rabbit Hemorrhagic Disease Virus, Iberian Peninsula

To the Editor: In this investigation, we found evidence for the apparent effects that a new variant of the rabbit hemorrhagic disease virus (RHDV) is having on native wild European rabbit (Oryctolagus cuniculus) populations on the Iberian Peninsula, and how this virus could threaten the conservation of endangered predators. Historically, European rabbits were extremely abundant on the Iberian Peninsula, which is in their native range. However, during the 20th century, the number of rabbits on the peninsula has declined >90%, mainly because of diseases (1). The first notable crisis among rabbits occurred during the 1950s concurrent with the arrival of myxomatosis among rabbit populations, which caused mortality rates of ≈90% (1), as registered in other regions. During the late 1980s, a calicivirus, RHDV, caused infections that made a strong impact on rabbit populations, causing initial mortality rates of 55%–75% in Iberia (1). Since their initial outbreaks, both diseases have become enzootic, and related mortality rates have decreased, in part because of increased host resistance, although the infections still play a major role in the dynamics of rabbit populations (2). In 2011, a new variant of RHDV, which appears to be closely related to an isolate originating in France that was described in 2010 (3), caused high mortality rates in some rabbit farms in Spain (4) and was also identified in an experimental wild rabbit plot in northern Spain (5). Since 2012, the new variant of RHDV has been detected in most rabbit farms in Spain (6), and in several wild populations distributed across Spain and Portugal (7), suggesting that it has rapidly spread throughout the Iberian Peninsula. This variant affects both of the wild rabbit subspecies (O. cuniculus cuniculus and O. c. algirus), and unlike the classical form of RHDV, it kills rabbits as young as 11 days of age and rabbits that have been vaccinated against classic RHDV (6,7). This scenario has raised concern for the survival of wild rabbit populations and its predators in this region. Data regarding rabbit trends seem to sustain this concern. For example, a long-term monitoring program in Aragon in northern Spain shows a notable decline in rabbit numbers during 2013 in populations that showed both long-term increasing and decreasing trends over the monitoring period (Figure, panels A, B, respectively). A similar trend has been observed in the main areas inhabited by the highly endangered Iberian lynx (Lynx pardinus). The lynx relies on rabbits for survival, because they represent >85% of the lynx’s diet (9). For instance, in Coto del Rey, the area within Donana National Park in southern Spain that traditionally held the highest rabbit densities and therefore represents the core of Iberian lynx populations in this national park, there was a decline in rabbits of >80% during 2012–2013 (Figure, panel C). Similar declines have been detected in low-density rabbit populations surveyed within Donana National Park (Figure, panel C). Rabbit numbers have also been progressively dropping in the proximity of the Yeguas River in Andujar and Cardena Natural Parks in southern Spain, where the largest Iberian lynx population currently lives: rabbit density was >3.5 rabbits/hectare in 2010 and <1 rabbit/hectare in 2013, a decline of ≈75% (10). In accordance with field surveys, hunters throughout Iberia claim that the number of rabbits harvested this season has decreased dramatically, pointing to a 70%–80% decline compared to the previous hunting season in some estates (A. Linares, pers. comm.). Figure Trends in rabbit abundance (number of rabbits/km) in Aragon and Donana National Park, northern and southern Spain, respectively, and in the number of Iberian lynx cubs born in the wild in Spain. A) Average rabbit abundance (+SD) of populations ... The European rabbit is a multifunctional keystone species of the Iberian Mediterranean ecosystem, where it serves as prey for >30 predatory animals, alters plant species composition and vegetation structure through grazing and seed dispersal, its excrement and urine have an effect on soil fertility and plant growth and provide feeding resources for invertebrates, and its burrows provide shelter for different species (9). Therefore, the decline in rabbit numbers could have potential cascading effects on ecosystem function. In fact, some of these effects may already be apparent on rabbit-reliant animals. On one hand, the sharp reduction in rabbit numbers observed in 2013 in the main lynx distribution area has been accompanied by a notable decrease in the number of lynx cubs born in the wild (Figure, panel D). On the other hand, the number of lynxes killed on roads doubled in 2013 (n = 14) in relation to 2012 (n = 7), and this has been linked to increased lynx displacements related to rabbit scarcity potentially associated with the impact of the new variant of RHDV (http://www.juntadeandalucia.es). The situation described exemplifies how emerging diseases can affect biodiversity conservation. It also highlights the importance of using wildlife monitoring schemes as detection tools for monitoring the impact of stochastic factors, such as the variant RHDV, on wildlife populations. Urgent management actions, designed within an Iberian rabbit conservation strategy that relies on a multidisciplinary framework, are needed to ensure the conservation of this keystone member of the Iberian Peninsula ecosystem and that of rabbit-reliant predators.

On the multifunctionality of hunting – an institutional analysis of eight cases from Europe and Africa

In many contemporary societies, multiple functions are connected to hunting. Here, we use the concept of multifunctionality to investigate the role of hunting beyond its traditional function of supplying meat. Hunting may contribute, for example, to biodiversity conservation, recreation and the preservation of economies and cultures in rural areas. Our comparative analysis of hunting in eight study sites in Europe and Africa examines the tensions and trade-offs between these ecological, economic and social functions of hunting, and investigates the interplay between the institutions regulating these functions to better understand conflicts over hunting. Based on this analysis, we present institutional arrangements that have developed to address these challenges of multifunctionality, and explore the institutional change brought about by such arrangements. Finally, we discuss the implications of this study for policy and institutional design.

The Role of Economic and Social Factors Driving Predator Control in Small-Game Estates in Central Spain

One of the most important human-wildlife conflicts in the world is that where predators are involved. Predators may compete with us for the same resources, such as game species. As a consequence, predators have been frequently controlled by game managers, which has negatively affected many predator populations worldwide. The understanding of human-wildlife conflicts requires a multidisplicinary framework that is rarely considered. We aim to evaluate the attitudes and behavior of game managers with regard to predator management in central Spain, as well as to explore factors that lead to these attitudes and behavior. Data were gathered through face to face interviews with game managers from 59 small-game hunting estates within central Spain. Predator control was employed in 90% of the estates, but control intensity was very variable among estates. Economic interests and perceptions about predators apparently influenced variation in control intensity. The main methods employed were cage-traps and shooting, but some illegal practices (e.g., leg-hold traps or snares without stopping devices) were also admittedly used for carnivores. Most managers considered that efficacy of legal methods for control of foxes (Vulpes vulpes) was very limited. Overall, nonselective methods, such as some types of snares, were more frequently employed in commercial than in noncommercial estates. Most managers believed that predators had an important effect on prey, and therefore that not doing it would lead to smaller hunting bags. Only managers from commercial hunting estates used stronger discourses such as that hunting would be impossible without carrying out predator control, which suggests that their tolerance for predators was lower than that of managers whose main motivation was not economic. Most managers considered that predator control was effective to reduce the number of predators, but only in the short term. Therefore, they highlighted the need of maintaining predator control every year. Our results highlight the important role that both social and economic factors (even stronger than ecological factors) play driving predator control, and therefore the need of incorporating these factors when making decisions to mitigate the human-predator conflict.