PDF The European rabbit: Past, Present and Future of the species in the Iberian Peninsula The European rabbit)is a native species of the Iberian Peninsula, where it was once abundant. In spite of this, it is nowadays considered a Near Threatened species. Find out why and what s being done to change it. Sara Otero e Filipa Alves 1 / 6
O declínio populacional na Península Ibérica quanto, quando, onde e porquê The population decline of wild rabbits in the Iberian Peninsula how much, when, where and why The wild rabbit, a species native to the Iberian Peninsula, was in the past very abundant in this region. In effect, the name Hispania used by the Romans to designate the Iberian territory, derived from a Phoenician term, literally means Island of rabbits. However, the Iberian populations of this lagomorph have registered, since the middle of the last century, an accentuated decline that recently worsened; because of this the IUCN attributed the status of Nearly Threatened in the Red List of Threatened Species in 2008. In effect, a study done in Spain in 2005 estimated that populations of rabbits in the country had decreased 95% in relation to the levels of 1950, and 80% relative to 1975. Another study came up with similar numbers: a decrease in population of 71% between 1973 and 1993 and of 49% from 1980 to 1990. In Portugal a study estimated a population decline of 24% between 1995 and 2002. 2 / 6
The reasons behind the decline are varied and have acted synergistically. The first causative factor of accentuated mortality would be the appearance of Myxomatosis, introduced by a French farmer in an attempt to control the negative impact of the rabbits on his crops. This epizootic was joined, in the case of Portugal at the beginning of the 1990s, by Viral (Rabbit) Hemorrhagic Disease. The effects of these two lethal epizootics were aggravated by a set of other factors. These include the loss and fragmentation of habitat (as a consequence of substitution of traditional agricultural practices by other more intensive ones and the installation, in scrubland areas, of plantations of fast-growing tree species), human persecution, overhunting and the absence of hunting management in some cases. These pressures, acting on the already overwrought populations of rabbits as a result of great competition with larger herbivores and intense predation (the rabbit is prey to 40 species of different predators in Mediterranean regions) resulted in their generalized collapse. 3 / 6
Consequences of the decline of wild rabbits at the ecosystem level Given the multiplicity of processes at the ecosystem level in which rabbits are involved, the decline of their population has impacts in various ways, some positive and others negative. The positive effects of the decrease in rabbit densities can be noted at the level of the vegetation. In effect, given their enormous capacity for population growth, their gregarious behaviour and their diet, populations of wild rabbit have a significant impact on all areas; they may or may not modify the structure of plant communities and cause damage in cultivated areas. In non-cultivated areas, we may see an impoverishment of the flora due to elimination of grasses and legumes as well as disturbances of natural regeneration of forest species. Meanwhile, damages to agricultural crops can lead to perturbations in the growth of winter cereals, resulting in losses for farmers. These positive effects are, however, offset by the enormous negative impact of the decrease in the abundance of rabbits. In effect, being a key prey species in Mediterranean ecosystems, the decline of populations of wild rabbit has serious implications for various species of predators. Rabbits enter into the diets of a wide range of predators, being the principal food source for diverse species in danger of extinction, such as the Spanish Imperial Eagle or Adalbert's Eagle (Aquila adalberti) and the Iberian lynx (Lynx pardinus). In the latter case, that of the most threatened feline in the world, the fall in densities of rabbit has directly contributed to the decline or the local/regional extinction of its populations, constituting a decisive limiting factor. On the other hand, the decrease in availability of wild rabbits provokes, in the case of generalist predators, a transferral of the pressure of predation on these to other prey species that may suffer as a result. In effect, it was verified that in France the accentuated reduction of rabbit populations caused by Myxomatosis led to, as an indirect consequence, an increase in the pressure of hunting on other species. These included hares and pheasant that, without the ecological plasticity of the rabbit, saw their populations diminish. 4 / 6
Reverting the effects of the decline promotion of the recuperation of populations Due to the importance of the rabbit as a small game species and the fact that it is vital for avoiding extinction of emblematic species as in the case of Iberian lynx, some measures to encourage the recuperation of populations of the lagomorph have been implemented in various zones. The techniques traditionally used to re-establish rabbit populations have included the control of generalist predators, especially foxes (Vulpes vulpes), and reintroduction with rabbits vaccinated and captured in areas where rabbits are still abundant or turning to animals resulting from reproduction in captivity. Besides these, another strategy is now widely used and is fundamental for the survival of the introduced animals. It is habitat management, with the objective of augmenting the environments carrying capacity, making it capable of sustaining healthy rabbit populations. Therefore, given that the species will have a greater probability of occurring in edge areas, where scrubland, crops and pastures overlap, the measures of environmental management include making available areas of shelter in the most exposed zones in the form of, for example, spots of bushy vegetation and small agglomerations of rocks and trunks - and of feeding areas in zones of scrubland by creating small seeded clearings. On the other hand, artificial protection should be foreseen in open areas without bushy vegetation or scrubland by means of construction of artificial dens marouços or by facilitating their creation by the rabbits themselves. 5 / 6
Habitat management measures have great potential insofar as the recuperation of rabbit populations; it has been demonstrated that they can, in themselves, lead to population increases of as much as eight times the initial density of rabbits, depending on the situation. Besides favouring the specialist predators that depend on them to survive, conservation of wild rabbits may prove beneficial to other species of prey. In effect, some studies refer that the reestablishment of healthy rabbit populations turns away a large part of the pressure exerted by predators on other small game species, especially the red-legged partridge, the hare and the common quail. Therefore, the recuperation of rabbit populations together with the application of adequate management measures permits encouragement of the other species of small game. 6 / 6