A longer confinement period favors European wild rabbit (<Emphasis Type="Italic">Oryctolagus cuniculus</Emphasis>) survival during soft releases in low-cover habitats

Rabbit restocking is widely used in Spain for conservation and/or hunting purposes; however, the success of rabbit restocking is generally low. Thus, many studies have assessed ways to reduce this problem, one of which is the use of a “soft-release” procedure whereby rabbits are acclimated to their release site for a variable time period prior to release. This study assessed the short-term effects of two soft-release confinement periods on the survival of rabbits during an experimental restocking program carried out in southwest Spain. The post-release survival rate of rabbits confined at the release site for six nights was significantly higher than that of rabbits confined for three nights. The longer acclimation period after rabbit translocation minimized mortality while rabbits adapted to their new environment.     

European rabbit population trends and associated factors: a review of the situation in the Iberian Peninsula

• 1 European rabbits are considered a keystone species in the Iberian Peninsula. Their populations have sharply declined over the past century, mainly due to habitat loss and the arrival of two viral diseases: myxomatosis in the 1950s and rabbit haemorrhagic disease (RHD) at the end of the 1980s. For the conservation of the Iberian Mediterranean ecosystem, it is important to determine whether rabbit populations are recovering two decades after the RHD outbreak, and to identify the factors associated with population recovery.
• 2 Here, we review the current knowledge on recent rabbit population trends in the Iberian Peninsula and the factors associated with these trends.
• 3 Although most rabbit populations are still declining in the Iberian Peninsula, a few seem to have recovered. In general, positive trends have been recorded in species‐friendly habitats characterized by non‐fragmented landscapes, interspersed patches of Mediterranean scrubland, good pastures and/or crops, soft soils that are suitable for warren construction and a Mediterranean climate with relatively high rainfall. Additionally, rabbits seem to be recovering better in areas where management practices (e.g. low hunting pressure, habitat management and predator control) are applied to increase their numbers.
• 4 From these findings, it is possible to identify five broad objectives for rabbit conservation in the Iberian Peninsula. First, it is clearly necessary to establish a long‐term programme for monitoring rabbit abundance and trends on a large scale. Second, the conservation and restoration of open Mediterranean scrubland should be a priority for stabilizing and maintaining existing healthy rabbit populations. Third, despite the lack of experimental evidence, management activities aimed at increasing the quantity and quality of both refuge and food should continue to be implemented. Fourth, legislation on the timing of the hunting season should be revisited following recommendations made by scientists. Finally, experimental approaches are required to investigate whether the control of generalist predators is a successful strategy to allow rabbit populations to recover.

     

Estimating the size of European rabbits consumed by predators: Relationship between body mass and tooth dimensions

A method for estimating body mass of European rabbitsOryctolagus cuniculus (Linnaeus, 1758) based on tooth dimensions is proposed. Regression models identified significant relationships between the body mass of 87 rabbits and individual tooth length, breadth, product of tooth length and breadth, and whether or not the individual was infected with myxomatosis. Dimensions of 10 of 14 different teeth explained over 80% of variation in body mass, and those teeth were selected as adequate predictors of rabbit body mass. Models were tested using teeth from 16 additional rabbits of known body mass. Body mass, predicted on the basis of 9 of the 10 selected teeth, was statistically indistinguishable from the observed values for all 16 individuals. When myxomatosis infection status of the rabbit was included in the model, all 10 selected teeth yielded predictions statistically indistinguishable from those observed. Prediction errors can be computed permitting statistical comparison of the average predicted value of body mass from different samples of rabbits. The model is useful in estimating rabbit body masses from teeth recovered from feces of predators and it will facilitate testing of hypotheses on size-selective predation. The method was applied to rabbit teeth found in fecal samples from the Iberian lynxLynx pardinus collected over a one-year period. Lynx preyed preferentially upon younger rabbits during the peak breeding period of this lagomorph.     

Observations on the epidemiology and interactions between myxomatosis, coccidiosis and helminth parasites in a wild rabbit population in Scotland

A study of the epidemiology of myxomatosis and the protozoan liver parasite, Eimeria stiedae, in a population of wild rabbits in Scotland from 1977 to 2010 is reported. Rabbits were collected on a monthly basis resulting in a total of 5,337 animals examined for the infections. The investigation showed that within any 1 year over the 34 years of the investigation the percentage of rabbits with myxomatosis varied between 0 and 24 %, while for E. stiedae infections fluctuated between 3 and 42 %. There were strong seasonal trends in the prevalence of myxomatosis with over 16 % being infected in September and October, and for E. stiedae, peaks of over 40 % of livers infected were recorded in July. From 2007 to 2010, faeces were also examined for coccidia oocysts and parasitic nematode eggs. Rabbits infected with the myxoma virus had mean oocyst counts of 73,665 per gram faeces, while rabbits not infected with the myxoma virus had counts of 31,952 oocysts per gram. Comparable figures for nematode faecal egg counts were 911 per gram in myxomatosis-infected animals and 427 per gram in uninfected animals. The elevated nematode faecal egg counts in rabbits with myxomatosis reflects increased worm burdens already reported, but the elevated counts of coccidial oocysts have not previously been reported. This would suggest that myxomatosis could compromise rabbit immunity to nematodes and coccidia.     

First description of sarcoptic mange in wild European rabbit (Oryctolagus cuniculus)

The European wild rabbit (Oryctolagus cuniculus) is a keystone species in the Iberian Mediterranean ecosystems being the staple prey of protected and endangered predators. Wild rabbits were once widespread, but the introduction of two viral diseases, myxomatosis in the 1950s and the rabbit hemorrhagic disease in 1989, resulted into a dramatic decline of its populations. Sarcoptic mange is a highly contagious parasitic infection caused by Sarcoptes scabiei. The first cases of sarcoptic mange in a wild rabbit population are recorded from a hunting area in Majorca (Balearic Islands, Spain). Five of 32 inspected rabbits (14.7%) were affected, with similar prevalences in summer and autumn. Sarcoptes scabiei were obtained from the edge of the lesions of two of the rabbits. The most frequently observed lesions were small areas of alopecia and crusts in the limbs. Affected limbs presented also a marked hypertrichosis and an apparent abnormal growth of the nails. One rabbit also presented lesions around mouth and nostrils. Parasitized rabbits were in significant lower body condition than healthy ones. According to previous reports of mange epizooties in other naïve wild species that caused marked short-term effects in their populations, this disease may pose a risk for the conservation of wild rabbit and their predators. Whether mange is endemic in rabbits from Majorca or it has been introduced is unknown. Game managers are encouraged to be aware of introducing sarcoptic mange during rabbit translocations.

     

Oxidative stress in wild European rabbits naturally infected with myxoma virus and rabbit haemorrhagic disease virus

The European rabbit (Oryctolagus cuniculus) is one of the most important vertebrate species in the Mediterranean Basin ecosystem. Over the last 60 years, the arrival of two viral diseases, myxomatosis and rabbit haemorrhagic disease, have led to dramatic declines in wild rabbit populations across the Iberian Peninsula. These diseases are currently endemic. Periodic outbreaks occur and have significant impacts on wild populations. Both infection types have diverse physiological effects on their hosts that are rooted in aerobic metabolic processes. To fight off these viruses, rabbits activate their immune systems. However, the production of immune defences generates reactive oxygen species that may consequently damage host tissues. Hypothesising that immune responses increase oxidative stress, we examined whether wild rabbits naturally infected with myxoma virus (MV) and rabbit haemorrhagic disease virus (RHDV) had high oxidative stress. Using blood samples, we measured anti-MV and anti-RHDV antibody concentrations and different oxidative stress markers (i.e., glutathione peroxidase, glutathione reductase, superoxide dismutase, catalase, and malondialdehyde). Our results show that rabbits that were seropositive for both MV and RHDV had high concentrations of malondialdehyde. Age and body condition were also positively related to dual seropositivity. No significant relationships were observed between serostatus and the concentrations of the other oxidative stress markers. Although we expected infection with MV and RHDV to be correlated with oxidative stress, the influence of external sources of oxidative stress (e.g., climatic conditions) likely made it more difficult to detect such relationships in wild rabbits.     

Establishing a serological surveillance protocol for rabbit hemorrhagic disease by combining mathematical models and field data: implication for rabbit conservation

Rabbit hemorrhagic disease (RHD) became endemic in wild rabbit (Oryctolagus cuniculus) populations in the Iberian Peninsula after its first arrival in 1988. This had significant implications for both the economy and environmental conservation because rabbits are one of the main game species in the Iberian Peninsula and a keystone species in the Mediterranean ecosystems. As a consequence, it is planned to include RHD surveillance in the Spanish Wildlife Disease Surveillance Strategy. Nevertheless, there is no practical methodology included in this program to help conservationists and gamekeepers understand the impact of disease on wild rabbit populations. Results from sera collected during the hunting season from 11 rabbit populations of Central and South Spain, which differed in their population abundance and trends, allowed us to use mathematical models to interpret the serological results gathered and determine the best strategy for finalizing a plan of RHD surveillance. Put simply, we focused our field surveys within the hunting season (October-January), and those times when the rabbit populations are at their highest (June or July). Field results showed that both rabbit abundance and population trend are closely related to the prevalence of RHD antibodies when rabbit abundance was at its annual low point (usually October-November). Rabbit population trends were positive only if antibody prevalence was high (>40%), and always negative if prevalence was low. Moreover, rabbit populations where abundance was low always showed low antibody prevalence. Since our models predicted a low variability in the prevalence obtained during the hunting season, it is suggested that future serological surveys should be carried out within this period to avoid problems related to the low sample size in low density rabbit populations.     

The short-term effect of total predation exclusion on wild rabbit abundance in restocking plots

About half a million rabbits are translocated in southwestern Europe every year for conservation and hunting purposes. However, the success of traditional rabbit restocking is generally extremely low, and this has been attributed to short-term predation by mammalian carnivores. Hence, recent recovery programs have tackled the problem of terrestrial predators with the use of exclusion fences, but no additional measures have been employed to avoid aerial predation. In this study, we have therefore conducted a field experiment to test the short-term effect of total predation exclusion in rabbit restocking enclosures, comparing rabbit abundance in plots which are only accessible to raptors (top-open plots) and plots which are accessible to neither carnivores nor raptors (top-closed plots). The results showed that the top-closed plots had higher rabbit abundance in the short term, and the highest difference in rabbit abundance between the two kinds of fences was attained in the first 2 weeks. We therefore conclude that the top-closed plots were an effective tool to increase rabbit abundance during the first weeks after release through the exclusion of raptor predation.     

Rabbits – their domestication and molecular genetics of hair coat development and quality

The European rabbit (Oryctolagus cuniculus) is the only representative of its genus living in present‐day Europe and North Africa, and all domestic rabbits are descendants of this one species, which is native to the Iberian Peninsula. There are over 300 breeds of rabbits that differ in size, coat color, length of ears and type of fur. Rabbits are bred for various reasons, such as for laboratory animals and a source of meat, wool and fur, as well as for pets and exhibition animals. The hair coat is a important economic trait of rabbits. Its development and quality are influenced by various factors, both environmental and genetic. The genetic mechanisms underlying its development have not been thoroughly researched. The aim of this review is to discuss the domestication of rabbits and the different aspects of rabbit genetics. A brief review of the properties of rabbit hair coat, hair coat development and hair cycle will be provided, followed by discussion of the factors regulating hair coat development, molecular control of hair coat development and the role of non‐coding RNAs in the regulation of gene expression in the hair follicles of rabbits. Information about genetic regulation of pathways could provide useful tools for improving hair coat quality and be of practical use in rabbit breeding.     

Is the wild rabbit (<Emphasis Type="Italic">Oryctolagus cuniculus</Emphasis>) a threatened species in spain? Sociological constraints in the conservation of species

The Wild rabbit (Oryctolagus cuniculus) is an endemic species of the Iberian Peninsula and is essential for the conservation of endangered predators. Rabbits are also of high importance as a hunting species. From 1988, rabbits suffered the severe effects of rabbit hemorrhagic disease, which caused large declines in most populations. Despite this fact, the National Red Data Lists continued to classify rabbits as a “Least Concern” species. We used available hunting bag data from 1973 to 2002 to model national trends of rabbit abundance and to evaluate the conservation status according to the criteria of the National Red Data List and the World Conservation Union (IUCN). Generalized Additive Models were used as the statistical framework. The rabbit population of Spain suffered a large decline of about 71% between 1973 and 1993. This decline was 49% in the period 1980–1990. Based on both Spanish and World Conservation Union criteria, rabbits should be listed as ‘Vulnerable’, which demands a Conservation Plan Program. We suggest that the lack of concordance between the best available evidence and the conservation status of the species is a consequence of sociological constraints in conservation decisions. Rabbit conservation could face strong opposition from important socio-economic lobby groups (hunters and farmers). As such, governments and researchers may prefer to exclude rabbits from any status category requiring conservation action, despite the evidence of decline. We call for the urgent development of a nation-wide conservation program for rabbits which includes both socioeconomic constraints and the available biological data on population trends.     

Restocking a keystone species in a biodiversity hotspot: Recovering the European rabbit on a landscape scale

Rabbit populations in Iberia remain at low densities in several areas in which their endangered predators still coexist, and the recovery of these populations is therefore urgent if the integrity of Iberian Mediterranean ecosystems is to be maintained. The enhancement of wild rabbit populations has been attempted through the use of in situ extensive rabbit captive breeding enclosures (restocking plots), which reduce mortality caused by terrestrial predators and dispersal movements and permit the breeding of young individuals which can then naturally disperse to settle in the surrounding areas. However, their effectiveness, the role of its size, the optimal habitat management that should be promoted around them and the habitat features remains uncertain. Here, we show results from a four year study of an ambitious rabbit restocking plan on a landscape scale. We measured rabbit abundance in a vast area in which thirty-two restocking plots were built to create an initial rabbit population for further dispersion, in addition to an intensive habitat management program. We also compared rabbit abundance between managed and unmanaged UTM cells of 2.5 km × 2.5 km. Our results showed that rabbit abundance was three times higher in managed cells, but four years after restocking, rabbit abundances had only reached the threshold needed to support stable Iberian lynx presence (at least 10 latrines per km^?1) in 9 of the 23 managed cells. Rabbit abundance was strongly affected by habitat treatment and scrub coverage. The increase of shelter was useful in low cover areas but ineligible in places with high scrub cover, where the increase of refuge plus scrub clearing to create pastures improve rabbit abundance more effectively. In the light of our results, restocking plots should be built only in places with suitable habitat, whereas pastures should be created in dense scrublands and refuge in low cover areas.     

Seroepidemiology of rabbit haemorrhagic disease (RHD) in wild rabbits (Oryctolagus cuniculus) in the United Kingdom

An extensive collection of blood samples from adult wild rabbits, from areas where Rabbit Haemorrhagic Disease (RHD) had not been recorded, was obtained from sites across the U.K. and parts of Eire over the winter of 1994/95. Sera from 946 animals were examined for antibodies to RHD. Antibody was found in all populations, varying between 20 and 100% depending on locality, and overall 64% of rabbits were seropositive in midwinter, supporting the view that non-pathogenic RHD or RHD-like caliciviruses, which are not producing clinical disease, circulate within rabbit populations. The serological response to these agents appears to confer significant immunity on rabbits subsequently exposed to the virulent RHD virus, so the disease will not be as devastating as myxomatosis was in the early 1950s (99% mortality) but at least one-third of the c. 40 million rabbits in the U.K. are susceptible.     

Protection against myxomatosis and rabbit viral hemorrhagic disease with recombinant myxoma viruses expressing rabbit hemorrhagic disease virus capsid protein.

Two myxoma virus-rabbit hemorrhagic disease virus (RHDV) recombinant viruses were constructed with the SG33 strain of myxoma virus to protect rabbits against myxomatosis and rabbit viral hemorrhagic disease. These recombinant viruses expressed the RHDV capsid protein (VP60). The recombinant protein, which is 60 kDa in size, was antigenic, as revealed by its reaction in immunoprecipitation with antibodies raised against RHDV. Both recombinant viruses induced high levels of RHDV- and myxoma virus-specific antibodies in rabbits after immunization. Inoculations by the intradermal route protected animals against virulent RHDV and myxoma virus challenges.     

Dying like rabbits: general determinants of spatio-temporal variability in survival

1. Identifying general patterns of how and why survival rates vary across space and time is necessary to truly understand population dynamics of a species. However, this is not an easy task given the complexity and interactions of processes involved, and the interpopulation differences in main survival determinants. 2. Here, using European rabbits (Oryctolagus cuniculus) as a model and information from local studies, we investigated whether we could make inferences about trends and drivers of survival of a species that are generalizable to large spatio-temporal scales. To do this, we first focused on overall survival and then examined cause-specific mortalities, mainly predation and diseases, which may lead to those patterns. 3. Our results show that within the large-scale variability in rabbit survival, there exist general patterns that are explained by the integration of factors previously known to be important at the local level (i.e. age, climate, diseases, predation or density dependence). We found that both inter- and intrastudy survival rates increased in magnitude and decreased in variability as rabbits grow old, although this tendency was less pronounced in populations with epidemic diseases. Some causes leading to these higher mortalities in young rabbits could be the stronger effect of rainfall at those ages, as well as, other death sources like malnutrition or infanticide. 4. Predation is also greater for newborns and juveniles, especially in population without diseases. Apart from the effect of diseases, predation patterns also depended on factors, such as, density, season, and type and density of predators. Finally, we observed that infectious diseases also showed general relationships with climate, breeding (i.e. new susceptible rabbits) and age, although the association type varied between myxomatosis and rabbit haemorrhagic disease. 5. In conclusion, large-scale patterns of spatio-temporal variability in rabbit survival emerge from the combination of different factors that interrelate both directly and through density dependence. This highlights the importance of performing more comprehensive studies to reveal combined effects and complex relationships that help us to better understand the mechanisms underlying population dynamics.     

Evolutionary history and molecular epidemiology of rabbit haemorrhagic disease virus in the Iberian Peninsula and Western Europe

Background  

Rabbit haemorrhagic disease virus (RHDV) is a highly virulent calicivirus, first described in domestic rabbits in China in 1984. RHDV appears to be a mutant form of a benign virus that existed in Europe long before the first outbreak. In the Iberian Peninsula, the first epidemic in 1988 severely reduced the populations of autochthonous European wild rabbit. To examine the evolutionary history of RHDV in the Iberian Peninsula, we collected virus samples from wild rabbits and sequenced a fragment of the capsid protein gene VP60. These data together with available sequences from other Western European countries, were analyzed following Bayesian Markov chain Monte Carlo methods to infer their phylogenetic relationships, evolutionary rates and demographic history.     

Complete Genomic Sequences of Rabbit Hemorrhagic Disease Virus G1 Strains Isolated in the European Rabbit Original Range

The complete genomic sequences of rabbit hemorrhagic disease virus (RHDV) strains isolated in 1995 (CB137) and 2006 (CB194) from wild European rabbits from Portugal are described. The strains were isolated in the original range of the European rabbit and assigned to genogroup 1 (G1), which is known to have persisted only in the Iberian Peninsula. ORF2 of isolate CB137 might encode a shorter minor structural protein, VP10.     

Allozyme evidence supporting southwestern Europe as a secondary center of genetic diversity for the common bean

Genetic diversity within a common bean ( Phaseolus vulgaris L.) collection, comprising 343 accessions from the Iberian Peninsula, was examined using six allozyme markers. Two major clusters corresponding to the Andean and Mesoamerican gene pools were identified. Both gene pools were characterized by specific alleles, with the former exhibiting Skdh(100), Me(100), Rbcs(100 or 98) and Diap-1(100), and the latter exhibiting Skdh(103), Me(100), Rbcs(100) and Diap-1(95). Some accessions from both clusters, deviating from these allozyme patterns, exhibited Skdh(100), Me(100), Rbcs(100) and Diap-1(95) or Skdh(103), Me(100), Rbcs(100) and Diap-1(100) allozyme profiles and were considered as putative hybrids.The levels of genetic variation has not been eroded since the introduction of the common bean from the American centers of domestication to the Iberian Peninsula. Instead, obvious signs of introgression between the two gene pools were observed, mainly among white-seeded genotypes. The intermediate forms adapted to the Iberian Peninsula could have emerged from initial recombination between Mesoamerican and Andean gene pools. The Iberian common bean germplasm is therefore more complex than previously thought, and contains additional diversity that remains to be explored for genetic and breeding purposes. The Iberian Peninsula could be considered as a secondary center of genetic diversity of the common bean, especially the large white-seeded genotypes.     

Ancient DNA reveals traces of Iberian Neolithic and Bronze Age lineages in modern Iberian horses

Multiple geographical regions have been proposed for the domestication of Equus caballus . It has been suggested, based on zooarchaeological and genetic analyses that wild horses from the Iberian Peninsula were involved in the process, and the overrepresentation of mitochondrial D1 cluster in modern Iberian horses supports this suggestion. To test this hypothesis, we analysed mitochondrial DNA from 22 ancient Iberian horse remains belonging to the Neolithic, the Bronze Age and the Middle Ages, against previously published sequences. Only the medieval Iberian sequence appeared in the D1 group. Neolithic and Bronze Age sequences grouped in other clusters, one of which (Lusitano group C) is exclusively represented by modern horses of Iberian origin. Moreover, Bronze Age Iberian sequences displayed the lowest nucleotide diversity values when compared with modern horses, ancient wild horses and other ancient domesticates using nonparametric bootstrapping analyses. We conclude that the excessive clustering of Bronze Age horses in the Lusitano group C, the observed nucleotide diversity and the local continuity from wild Neolithic Iberian to modern Iberian horses, could be explained by the use of local wild mares during an early Iberian domestication or restocking event, whereas the D1 group probably was introduced into Iberia in later historical times.     

Demography,dispersal and movement pattern of <Emphasis Type="Italic">Euphydryas aurinia</Emphasis> (Lepidoptera: Nymphalidae) at the Iberian Peninsula: an alarming example in an increasingly fragmented landscape?

Mediterranean countries like Portugal and Spain, so far characterised by extensive traditional land use over major parts of their territories, have been less affected by species losses. However, they are facing severe changes. As a model organism we chose the butterfly Euphydryas aurinia, highly threatened in Central Europe but still common at the Iberian Peninsula, for a mark-release-recapture survey in the western Algarve. We examined key factors for stabile metapopulation systems to assess the ability of long-term survival in the increasingly fragmented landscapes of the Iberian Peninsula. The density of the examined population was high (ca. 2,200 individuals/ha). However, the MRR-based proportion of individuals moving longer distance classes showed a better fit to the negative exponential function than to the inverse power function implying restricted dispersal behaviour. The orientation pattern of short distance movements (<10 m) proved to be independent from habitat structures. In contrast, longer movements (>10 m) were strongly orientated along the main habitat axes revealing the importance of internal habitat structures for the orientation of dispersing individuals. Based on these data, we discuss the severe consequences for the fauna of the Iberian Peninsula in an increasingly fragmented and monotonous landscape.     

Mortality patterns over 3 years in a sparse population of wild rabbits (Oryctolagus cuniculus) in New Zealand, with an emphasis on rabbit haemorrhagic disease (RHD)

A sparse rabbit population in New Zealand was monitored over 3 years to assess the temporal dynamics of rabbit mortality, in particular to understand the mortality patterns due to rabbit haemorrhagic disease (RHD). A total of 107 deaths were recorded, of which 93 could be classified by cause. The predominant cause of mortality was predation (47% of deaths), followed by RHD (20%). Deaths due to RHD were clustered in time (within 3 weeks), predation occurred most actively from late autumn to spring, while other causes of death did not show pronounced seasonal peaks. No differences in cause-specific death risk were observed between sexes. Predation was the main cause of death in younger animals, while RHD mortality occurred mainly in older rabbits. This study has shown that the impact of RHD can vary considerably between years, indicating that a variety of risk factors are required to initiate a RHD epidemic with a high mortality rate among rabbits.