Suchergebnisse

Context
Warrens are central to rabbit biology and available warren space can set a limit to the number of rabbits living in an area. Therefore, quantifying and analysing the distribution of rabbit warrens is a key step towards the management of the species in agricultural lands where it causes significant damage to crops.

Aims
The present study investigates the distribution and spatial pattern of wild rabbit (Oryctolagus cuniculus) warrens in an intensively managed agricultural landscape within the rabbit's native range in semiarid southern Spain, where rabbits constitute an emerging pest problem.

Methods
All natural rabbit warrens within two sites were mapped, and information on their size, use and protection was recorded. The effects of environmental variables (e.g. habitat features and distances to key resources) in determining warren occurrence were evaluated using binomial generalised linear models (GLM).

Key results
The main variable explaining warren occurrence was the distance to the nearest neighbouring warren. Habitat variables and the distances to key resources played only a secondary role, and were mainly related to frequent ploughing linked to agricultural practices that prevent warren construction.

Conclusions
Habitat instability resulting from agricultural practices (i.e. frequent ploughing and intensive human disturbance) promotes warren construction on stable grounds only and partly explains the clumped spatial pattern found. However, warren occurrence in intensively managed agricultural areas seems to be more constrained by the proximity of neighbouring warrens that would facilitate rabbit recolonisation from patches nearby. Despite becoming increasingly scarce as a result of agricultural intensification, these unploughed remnants may act as safe islands for digging warrens.

Implications
The management of unploughed patches and the connectivity among them in semiarid agroecosystems of southern Spain is therefore of utmost importance to the management of rabbits as an agricultural pest.

Many translocation methods have been tested in southern Europe in recent decades to increase the translocation success of the European wild rabbit (Oryctolagus cuniculus L.) for both conservation and game purposes. The main problem experienced during such translocations is the high short-term (7 days) mortality attributed to predation during the days immediately following rabbit release. In this study, we test the effect of the exclusion of terrestrial predators on the survival of translocated rabbits for recovery purposes. Four translocation plots (4 ha with 18 artificial warrens each) were constructed, two of them with a fence to exclude terrestrial predators. In all, 724 rabbits were released to the translocation plots in five batches and forced to remain inside warrens for 7 days. Following liberation, exclusion of predators did not increase rabbit survival in the short term. Contrary to expectations, three months after release, survival of rabbits in the unfenced plot was slightly, but not significantly, higher than in the fenced plot (0.57 and 0.40 respectively). Although predator control is a frequent management practice associated with rabbit translocations, our results suggest that it may not favour rabbit survival rate as much as the adaptation of rabbits to the release site.

The recreational use of natural resources requires the implementation of sustainable management systems. However, the existence of socioeconomic interests and the difficulty involved in applying evidence-based criteria often hinder this implementation. The European wild rabbit (Oryctolagus cuniculus) is an appropriate case with which to study the recreational hunting governance systems. This species has, in recent decades, undergone important population changes in its native area, the Iberian Peninsula, where it plays a triple role as a game, pest and key ecological species. The rabbit is consequently intensively managed for hunting purposes, for the conservation of rabbit-dependent predators and in order to mitigate damage to crops. In this paper, we study the governance system of rabbit hunting through the use of questionnaire surveys distributed to managers working for Spanish regional governments. We repeated the survey in 2001 and 2016 in order to evaluate how the system had evolved over a 15-year period of important changes in rabbit population abundance. We found two different responses to these changes. The growth of rabbit populations in provinces in which rabbits cause crop damage in farmland areas has been dealt with an increase in hunting pressure, derived from both administrative decisions and hunters' management. However, in provinces where rabbit populations have sharply declined in natural vegetation (non-farmland) areas, the management seems to be driven mostly by inertia, with a high influence of tradition and little use of evidence on administrative decisions. Hunters in these provinces have changed their management practices to little or no extent, where even the high importance of rabbit hunting and its (moderate) economic importance do not appear to provide an incentive for the change required.

Context
Humans have introduced lagomorph species in areas outside their native ranges for their meat, fur or value as game species. Assessing the rate of success of lagomorph introductions is vital to address the ecological damage they may cause. Cases of failed lagomorph introductions in apparently suitable areas may also shed light on mechanisms that may deter invasion, which are useful in developing strategies for population control. In Spain, it has been suggested that hunters introduced the non-native eastern cottontail (Sylvilagus floridanus) to compensate for the recent drastic declines of the native European rabbit (Oryctolagus cuniculus).

Aims
Our main goals were to investigate (1) whether Sylvilagus rabbits have indeed been introduced by hunters across Spain, and (2) whether the species has become established in Spanish ecosystems.

Methods
We interviewed 311 hunters or naturalists across Spain. The questionnaires inquired about the characteristics of game management in each locality, including the frequency of rabbit restocking, and particularly whether Sylvilagus rabbits had been released in the surveyed localities. In addition, we sampled 192 rabbit populations (n=3974 individuals) across Spain by using molecular analysis to determine whether Sylvilagus rabbits were present in these areas.

Key results
Our interview results suggest that Sylvilagus rabbits may have been released in 6% of the 311 localities surveyed. However, molecular analyses failed to confirm their persistence, because all samples belonged to O. cuniculus.

Conclusions
We infer that Sylvilagus rabbits failed to establish themselves in Spain, although interviewees reported their introduction. Several reasons may explain the unsuccessful establishment of this species, such as a low propagule pressure, competition with native species, predation, inability to cope with local pathogens and unsuitable climatic conditions.

Implications
The risk of future introductions of non-native game species can be reduced through the implementation of stricter regulations of animal releases into the wild. Long-term monitoring networks should be developed to help identify non-native game species before they become established and spread to neighbouring areas, thereby preventing any ecological or economic impacts these species may cause.