Ecology

Biology of the savage rabbit

The field rabbit or savage rabbit (Oryctolagus cuniculus L., 1758), belongs to the Lagomorphs’ type and to the family of the “leporides” (hares and rabbits). The weight of an adult specimen goes from 1’5 kg to 2’5 kg. It has long ears, up to 7 centimetres and a very short tail. In the same way than the other lagomorphs, his hind limbs are powerful and strong because of their adaptation to the race. The rabbit is a key species in the Mediterranean ecosystems. Its abundance and wide distribution make to exist in the Iberian Peninsula more than 39 species of birds and the mammalians that depredate on them.  It is, therefore, the main prey of emblematic and endemic species from the Iberian Peninsula like the Iberian lynx or the Iberian imperial eagle. Furthermore, because of its abundance and the excellent quality of its meat, the rabbit has been consumed in an assiduous way by the humans, mainly in the rural world, establishing historically the most common piece of “smaller” hunting in Spain.

 Savage rabbit

Feeding

The rabbit is an opportunistic herbivore, which varies its feeding depending on the environment characteristics. Its diet includes herbaceous green plants and dry, roots, bushy species and even arboreal (leaves and barks). However, to reach its maximum reproductive potential they need composed plants, this is, leguminous and perennial grasses of small size and with a tendency to form lawn. One of the most important adaptations of the species to the Mediterranean ecosystems is the capacity to take advantage of the dry grass as a trophic resource. That is why great populations of rabbits exist in sub-desert areas of the Iberian Peninsula.

The rabbit spends between the 30% and the 60% of its time to feeding, and up to 20% to social relations, and the rest to cleaning and leisure. The species’ digestive strategy to take advantage of the lignified and not much digestible food is the caecotrophy. It consists in the double passing of the food through the alimentary canal. On not having a long complex digestive track like the ruminants, the rabbits have adapted themselves to ingest cecotrophs (fresh droppings formed by food remains that only have passed once through the alimentary canal) to optimize the utilization of nutrients. This process takes place in moments of rest and supposes an increase of 50% of the time of permanence of the food in the organism. In addition, it induces the formation of 2 types of droppings: the soft ones, rich in bacteria and proteins that are re-ingested; and the hard ones, that are definitely settled on the floor. These are settled in a particular place by the rabbits of the same social group, forming latrines.  The latrines are visible elements that demonstrate the presence of wild rabbits in a certain area, and they are used to estimate the abundance of rabbits in a given area.

Habitat

The wild rabbit is present in a wide variety of media, being the Mediterranean bush the habitat where it presents greater abundances (especially if there are cultivated zones and flat or moderately hilly relief). Their higher population densities are reached in meadows where the bush is abundant (40% in coverage) and in the pastures or crops. There are also great population in areas of sub-desert scrub in dry environments. The height limits the species, being rarefied in general from 1500 meters in the North of the peninsula and from the 1900
meters in the South. it presents its biggest population density in the areas where the climate is continental or Mediterranean and the substratum allows the easy construction of burrows, avoiding the lime areas. In general, the low temperatures and high precipitations are not appropriate for a species that prefer arid and warm climates, although in small-scale it has more abounds near riverbanks.

Reproduction

The wild rabbit is one of the few species of vertebrates in which the female can be receptive all year. The factor that determines the entry of females in zeal is the quantity of protein ingested. In consequence, the reproductive period of rabbit depends on the quality and abundance of the pasture, and therefore, on the season and rainfall intensity. In general terms, the reproduction usually happens between November and June, although there are described cases in which the reproductive period can be much longer. After a short maternal dependence (20-30 days) the little rabbits (from 3 to 6) acquire sexual maturity in a few months. Although females can enter a new zeal while nursing/breast-feeding a previous litter (by what are possible 12 litters in a year) the most habitual thing is that they take place between two and four.

Social organization and behaviour

Generally, the rabbit lives in burrows that host social groups which size depends on the size of the warren, as well as the quality and structure of the habitat. The next familiar groups form a colony where the individual exchanges are common. In each group is established a social hierarchy between males, females and young people and adults. The dominant males cover the high-status females, and the low-status females have to create a breeding chamber in less protected areas of the burrow or even outside it. The household territory is mainly defended by the dominate males, although all individuals take part in these tasks.

The pattern of activity is influenced by the structure of the predators’ community. 

In the Iberian Peninsula it is mainly bimodal with activity peaks in the twilight and a moderate night activity. On the other hand, in areas where the species has been introduced and where they have a lower risk of depredation, there are no clear patterns of activity.