Gastropod associations within Malham Tarn, Yorkshire

A survey of gastropod species associations was undertaken in one locus, i.e. Malham Tarn, Yorkshire. This ranged through both the major weed beds and the rocky shores. A semiquantitative analysis, in terms of both presence-absence and relative abundance indices, suggested a clear distinction between the snail fauna present in the weed beds and that on the rocky shores, and also indicated a separation of faunas within these two major habitat types. The latter was closely correlated with degree of exposure. From this, and other evidence, it was suggested that wind, via wave action, may be a critical determinant of both the qualitative and quantitative aspects of biocoenotic structure in large bodies of fresh water.     

Transferrin (Tf) polymorphism in wild rabbit, Oryctolagus cuniculus

Evidence for two new alleles (TfC and TfD) at the transferrin locus (Tf) in wild rabbit, Oryctolagus cuniculus, is presented. Blood samples were collected in Continental Portugal (178 individuals), and in the Azores Islands of Terceira (52) and S. Miguel (59). The frequency of TfA, which is the only allele detected up to now in domestic rabbits, varied from 0.20 +/- 0.13 to 0.95 +/- 0.05 in the populations sampled in Continental Portugal. In the island populations sampled the frequency of TfA was greater than 0.8.     

The incidence of helminth parasites from the wild rabbit Oryctolagus cuniculus (L.) in eastern Scotland

Samples of wild rabbits were collected each month over the six-year period 1977-82 and their intestines and abdomens examined for helminths. Three species of nematode, four of cestode and one trematode were found. Graphidium strigosum was recorded in 33% of the 786 rabbits, Trichostrongylus retortaeformis in 79%, Passalurus ambiguus in 14.2%, Cittotaenia pectinata in 37%, C. denticulata in 11%, Coenurus pisiformis in 3%, Cysticercus serialis in 0.1% and Fasciola hepatica in 0.1%. G. strigosum and P. ambiguus infections were greatest in the older heavier animals whereas juvenile rabbits had the heaviest T. retortaeformis nematode burdens. Seasonal fluctuations were observed in G. strigosum, T. retortaeformis, P. ambiguus and Cittotaenia denticulata. The sex and reproductive state of the female rabbit did not have any significant effect on either the nematode or cestode worm burdens. Myxomatosis was shown to significantly increase the worm burden of T. retortaeformis and raise that of P. ambiguus. No nematode or cestode from domesticated animals were recovered and it was concluded that since F. hepatica was found only once rabbits did not constitute a serious hazard to the farm animals grazing the area.     

Coccidiosis of the wild rabbit (Oryctolagus cuniculus) in France

In 1998-1999 a survey of coccidiosis in wild rabbits was carried out in six different localities in France. About five individuals were caught monthly in each locality and a total of 254 wild rabbits was examined. Ten species of Coccidio were identified: Eimeria perforans, E. flavescens, E. piriformis, E. exigua, E. media, E. magna, E. coecicola, E. stiedai, E. roobroucki, E. intestinalis. Intensity of infection in young individuals was higher than in adults. Intensity was highest in winter but, as there are no young rabbits in winter, in young individuals it was higher in spring and autumn than in summer. Intensities were higher in the northern rather than in southern localities. Ranking of prevalence was remarkably stable, in contrast to the variability of the parasitic load. The equilibrium between congeneric species of rabbit coccidia (stable prevalence rank, variable parasitic load) is thought to be probably the consequence of the opportunistic feeding habits of rabbits.     

Factors affecting the distribution of some Phryganeaeid (Trichoptera) in Malham Tarn, Yorkshire

This paper describes a distribution problem involving Agrypnetes crassicornis and Phryganea obsoleta (Trichoptera : Phryganeidae) in Malham Tarn, Yorkshire. The only suitable habitat for their larvae is the offshore vegetation, chiefly Chara delicatula, but owing to the specialized egglaying behaviour of this family and the absence of other sites, the eggs of Agrypnetes crassicornis are laid on the exposed rocky shoreline. The situation with Phryganea obsoleta differs in that the emergence of Potamogeton spp. provides new oviposition sites away from the shore. Investigations on both species however have provided further support for an hypothesis which postulates the importance of wind-induced water movements in rapidly dispersing newly hatched insect larvae to the favourable habitats in deep water.     

The invasion of Argentina by the European wild rabbit Oryctolagus cuniculus

• 1 We provide an updated distribution and dispersal rate of the introduced European rabbit Oryctolagus cuniculus in Argentina.
• 2 According to our results this invasive species is currently colonizing parts of Mendoza and Neuquén Provinces, where rivers are very important in the spread of the rabbits, especially in unfavourable areas. The maximun rate of dispersal registered in this study was 9 km/year.
• 3 Some information was obtained to indicate that the presence of this exotic species threatens agriculture, livestock, forestry, and natural ecosystems of the Patagonia region.

     

Helminths of the wild rabbit (Oryctolagus cuniculus) in Macaronesia

Two hundred and four rabbits from 8 Macaronesian islands (Pico, San Jorge, San Miguel, Terceira, and Flores from Azores Archipelago; Tenerife and Alegranza from Canary Islands; and Madeira from Madeira Archipelago) were examined for helminth parasites between 1995 and 2000. Three species of cestodes, Taenia pisiformis (larvae), Andrya cuniculi, and Mosgovoyia ctenoides, and 5 species of nematodes, Trichuris leporis, Graphidium strigosum, Trichostrongylus retortaeformis, Passalurus ambiguus, and Dermatoxys hispaniensis, were identified. Only 3 species (M. ctenoides, T. retortaeformis, and P. ambiguus) were regularly distributed over the 3 archipelagos. Taenia pisiformis was not collected in Madeira, nor was A. cuniculi in the Azores and G. strigosum in the Canary Islands. Trichuris leporis and D. hispaniensis were only found in Madeira. Significant differences in the general prevalence of the nematodes G. strigosum and T. retortaeformis were detected between Azores and Madeira. The prevalence of T. retortaeformis differs significantly between the Azores and the Canaries and that of P. ambiguus was higher in Madeira than in Azores and Canaries. The helminth richness found in the wild rabbit in these Macaronesian archipelagos was very low compared with the Palearctic helminth fauna of this host. The wild rabbit was introduced from the Iberian Peninsula into different Macaronesian islands. Helminths introduced with Oryctolagus cuniculus into these islands also are commonly found in Iberian wild rabbits, which are excellent colonizers, as demonstrated in this study.     

The helminth parasites of the wild rabbit Oryctolagus cuniculus and their effect on host condition in Dunas de Mira, Portugal

The present study focuses on the helminth parasite community of the wild rabbit in a sand dune area in Portugal over a 5-year period. The influence of host sex and year on the composition of the helminth community is assessed, along with the potential effect of the detected helminths on host body condition. The basic structure of the helminth community comprises Mosgovoyia ctenoides, Graphidium strigosum, Trichostrongylus retortaeformis, Nematodiroides zembrae and Passalurus ambiguus. Mean intensities of G. strigosum varied between years. General G. strigosum intensities were also found to vary according to both year and host sex, but not according to the interaction of both factors. When assessing the effect of helminths on rabbit body condition (expressed by the kidney fat index), higher burdens of M. ctenoides, a cestode that presents a relatively large body mass, were found to induce a reduction in rabbit condition.     

Cryptosporidium cuniculus in the rabbit (Oryctolagus cuniculus)

Cryptosporidium cuniculus was identified by light and electron microscopy in two apparently healthy rabbits. Organisms were firmly attached at the brush borders of intestinal epithelial cells. Cellular alterations were minimal, consisting of elongation and shortening of microvilli adjacent to the attachment sites of organisms. Various developmental stages of cryptosporidium were identified by electron microscopy.     

Patterns of parasite aggregation in the wild European rabbit (Oryctolagus cuniculus)

Understanding the factors controlling the distribution of parasites within their host population is fundamental to the wider understanding of parasite epidemiology and ecology. To explore changes in parasite aggregation, Taylor's power law was used to examine the distributions of five gut helminths of the wild rabbit. Aggregation was found to be a dynamic process that varied with year, season, host sex, age class, and myxomatosis. Yearly and seasonal changes are thought, in the main, to be the result of variations in weather conditions acting upon infectious stages (or intermediate hosts). Evidence in support of this was the comparatively low degree of fluctuation in the aggregation of the pinworm, Passalurus ambiguus, as the infectious stage of this parasite is likely to be less susceptible to environmental variation. Host age had a marked effect on the level of aggregation of all parasites, but this effect varied between parasite species. P. ambiguus, Trichostrongylus retortaeformis and Cittotaenia denticulata aggregation were lower in adult than juvenile rabbits whilst Graphidium strigosum and Mosgovoyia pectinata aggregation tended to increase with age. Host immunity is thought to be responsible for these differences. Differences in aggregation for different parasites were also seen when the rabbit population was split into males and females. Myxomatosis had a marked effect on helminth distribution with substantially less aggregation in rabbits showing clinical signs of the disease.     

Influence of host weight, sex and reproductive status on helminth parasites of the wild rabbit, Oryctolagus cuniculus, in Navarra, Spain.

A study was carried out in Navarra (northern Spain) on the influence of the weight, sex and reproductive status (lactant, pregnant or lactant + pregnant females and testicular weight for males) of the wild rabbit (Oryctolagus cuniculus) on two cestodes species: Andrya cuniculi and Mosgovoyia ctenoides and four intestinal nematodes: Graphidium strigosum, Trichostrongylus retortaeformis, Nematodiroides zembrae and Dermatoxys hispaniensis. A significantly higher prevalence of A. cuniculi was detected in lactant + pregnant females compared with non-breeding females. Trichostrongylus retortaeformis and N. zembrae showed a significantly higher mean intensity in lactant and lactant + pregnant females than in non-reproductive females. Trichostrongylus retortaeformis presented a higher mean intensity in females than in males, and the mean intensity of the same parasite species was significantly lower in active and inactive males compared with lactant and lactant + pregnant females. There were no significant differences between sexes in the prevalence of helminth parasites. No significant correlation was detected between host weight and the intensity (of infection) of helminths studied. No significant differences in the prevalence and mean intensity of the two cestode species were observed in the three weight categories studied (kittens, juveniles and adults). The prevalence of G. strigosum and mean intensity of T. retortaeformis were significantly higher in older heavier animals than in juveniles.     

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.

     

Parasitic helminths of the wild rabbit, Oryctolagus cuniculus, in different bioclimatic zones in Tenerife, Canary Islands

Faunistic and ecological analyses of the wild rabbit helminth fauna were undertaken in Tenerife island (Canary Islands). Rabbits were collected between 1998 and 2000 in seven bioclimatic zones in Tenerife selected by orientation and altitude. Five parasite species were identified, three cestodes (Taenia pisiformis (larvae), Andrya cuniculi and Mosgovoyia ctenoides) and two nematodes (Trichostrongylus retortaeformis and Passalurus ambiguus). Taenia pisiformis presented an irregular distribution with significant differences in prevalences between the zones. Andrya cuniculi was only found in two zones and there were no significant differences in prevalence values. Mosgovoyia ctenoides presented a wide distribution with significant prevalences, which were higher in northern compared to southern zones. Trichostrongylus retortaeformis was absent in the low southern zones of the island. Passalurus ambiguus was found in all zones with no significant difference in the prevalence of infection. The differences in prevalences are likely to be explained by abiotic factors in the case of T. retortaeformis, and by the absence of definitive and intermediate hosts in the case of T. pisiformis and A. cuniculi, respectively. All parasite species in Tenerife are common helminths in the Iberian Peninsula, from which their rabbit hosts originated. No significant differences were recorded in the mean intensities of infection of any of the parasite species identified.     

Seasonal changes in condition, reproduction and fecundity in the wild European rabbit (Oryctolagus cuniculus)

A total of 1248 rabbits ( Oryctolagus amiculus ) were shot on farmland in Cambridgeshire, UK over a period of three years. This provided pooled estimates of changes in reproductive and body condition and of fecundity during the annual cycle. Both males and females showed a significant annual cycle in reproductive condition as indicated by changes in the size of the gonads and accessory glands of reproduction. No females were pregnant during October, November and December, but males with active spermatogenesis were found during every month of the year. The distribution of pregnancies through the year showed that the reproductive season varied greatly between individuals. Peak fecundity occurred during April, May and June. On average, each female conceived 23.9 and suckled 17.2 young per breeding season. Proportionately more young died during the early stages of the reproductive season. The body weight of adult males, but not of females, varied seasonally. Body condition (kidney fat index) in adults was maximal at the start of the breeding season and minimal at the end.     

Grain sowing aimed at wild rabbit Oryctolagus cuniculus L. enhancement in Mediterranean environments

Although habitat management practices focussed on the enhancement of hunting and protection of threatened species are common, the scientific validation of such practices is scarce. The wild European rabbit Oryctolagus cuniculus L., a hunted and threatened species in its native range, is at the same time a key species for the preservation of threatened Mediterranean predators. Cereal sowing is one of the most common practices to augment the food supply of rabbits, and it is used not only by hunters but also by conservationists. At present, limited scientific information is available regarding the effectiveness of cereal sowing. To evaluate its effectiveness, we analysed data on sowing trials conducted in 125 plots, located in 14 private estates throughout central Spain, most of them with low density populations. Brush was cleared from 44 of these plots prior to sowing. Our results indicated that rabbits preferentially selected sown areas over control (unsown) areas. This selection increased in plots that represented suitable habitats for rabbits, such as pasturelands, as well as when thicket islands and natural or artificial shelters were available within the sown plots. Local enhancement of rabbit populations was also observed. These positive results were also obtained regardless of the initial habitat conditions, not only in the treatment plots but also in the surrounding area. Our recommendations can be broadly applied for managing rabbit-dependent threatened species.