European rabbit (Oryctolagus cuniculus)

The European rabbit (Oryctolagus cuniculus) or coney is a species of rabbit native to southwestern Europe (including Spain, Portugal and western France) and to northwest Africa (including Morocco and Algeria). It has been widely introduced elsewhere, often with devastating effects on local biodiversity. However, its decline in its native range (caused by the diseases myxomatosis and rabbit calicivirus, as well as overhunting and habitat loss), has caused the decline of its highly dependent predators, the Iberian lynx and the Spanish imperial eagle. It is known as an invasive species because it has been introduced to countries on all continents with the exception of Antarctica, and has caused many problems within the environment and ecosystems. Feral European rabbits in Australia have had a devastating impact, due in part to the lack of natural predators there.

The European rabbit is well known for digging networks of burrows, called warrens, where it spends most of its time when not feeding. Unlike the related hares (Lepus spp.), rabbits are altricial, the young being born blind and furless, in a fur-lined nest in the warren, and they are totally dependent upon their mother. Much of the modern research into wild rabbit behaviour was carried out in the 1960s by two research centres. One was the naturalist Ronald Lockley, who maintained a number of large enclosures for wild rabbit colonies, with observation facilities, in Orielton, Pembrokeshire. Apart from publishing a number of scientific papers, he popularised his findings in a book The Private Life of the Rabbit, which is credited by Richard Adams as having played a key role in his gaining "a knowledge of rabbits and their ways" that informed his novel Watership Down. The other group was the Commonwealth Scientific and Industrial Research Organisation (CSIRO) in Australia, where numerous studies of the social behavior of wild rabbits were performed. Since the onset of myxomatosis, and the decline of the significance of the rabbit as an agricultural pest, few large-scale studies have been performed and many aspects of rabbit behaviour are still poorly understood.

Description
The European rabbit is smaller than the brown and mountain hare, and lacks black ear-tips, as well as having proportionately shorter legs. An adult European rabbit can measure 40 centimetres (16 in) in length, and weigh 1,200–2,000 grams (2.6–4.4 lb). The hind foot measures 8.5–10 centimetres (3.3–3.9 in) in length, while the ears are 6.5–7.5 centimetres (2.6–3.0 in) long from the occiput.

Size and weight varies according to food and habitat quality, with rabbits living on light soil with nothing but grass to feed on being noticeably smaller than specimens living on highly cultivated farm-lands with plenty of roots and clover. Pure European rabbits weighing 5 kilograms (11 lb) and upwards are uncommon, but are occasionally reported. One large specimen, caught in February 1890 in Lichfield, was weighed at 2.8 kilograms (6 lb 2 oz). Unlike the brown hare, the male European rabbit is more heavily built than the female. The penis is short, and lacks a baculum and true glans.

The fur of the European rabbit is generally greyish-brown, but this is subject to much variation. The guard hairs are banded brown and black, or grey, while the nape of the neck and scrotum are reddish. The chest patch is brown, while the rest of the underparts are white or grey. A white star shape is often present on kits' foreheads, but rarely occurs in adults. The whiskers are long and black, and the feet are fully furred and buff-coloured. The tail has a white underside, which becomes prominent when escaping danger. This may act as a signal for other rabbits to run.

Moulting occurs once a year, beginning in March on the face and spreading over the back. The underfur is completely replaced by October–November. The European rabbit exhibits great variation in colour, from light sandy, to dark grey and completely black. Such variation depends largely on the amount of guard hairs relative to regular pelage. Melanists are not uncommon in mainland Europe, though albinoes are rare.

Life history and behaviour
Social and territorial behaviours
The European rabbit lives in warrens that contain 2-10 other individuals living in smaller groups to ensure greater breeding success. Territoriality and aggression contribute greatly to the rabbits' maturation process, and help ensure survival of the population. Females tend to be more territorial than males, although the areas most frequented by females are not defended. Territories are marked with dung hills. The size of the species' home range varies according to habitat, food, shelter, cover from predators, and breeding sites, though it is generally small, encompassing about 0.3-0.7 hectares. Except during times of low rabbit density and abundance of high-quality food, male ranges tend to be larger than those held by females. The European rabbit rarely strays far from its burrow: when feeding on cultivated fields, it typically only moves 25 metres away from its burrow, and rarely 50 metres. It may however move as far as 500 metres after an abrupt change in environment, such as a harvest. This behaviour may be an anti-predator adaptation, as rabbits in areas where predators are under rigorous control may move three times further from their burrows than those in areas without predator management.

The European rabbit is a gregarious animal, which lives in stable social groups centred around females sharing access to one or more burrow systems. However, social structures tend to be looser in areas where burrow construction is relatively easy. Dominance hierarchies exist in parallel for both bucks and does. Among bucks, status is determined through access to does, with dominant bucks siring the majority of the colony's offspring. The dominant does have priority access to the best nesting sites, with competition over such sites often leading to serious injury or death. Subordinate does, particularly in large colonies, typically resort to using single-entrance breeding spots far from the main warren, thus making themselves vulnerable to fox or badger predation.

Reproduction and development
In the European rabbit's mating system, dominant bucks exhibit polygyny, whereas lower-status individuals (both bucks and does) often form monogamous breeding relationships. Rabbits signal their readiness to copulate by marking other animals and inanimate objects with an odoriferous substance secreted though a chin gland, in a process known as "chinning". Though male European rabbits may sometimes be amicable with one another, fierce fights can erupt among bucks during the breeding season, typically January to August. A succession of litters (usually 3-7 kittens each) are produced, but in overpopulated areas, pregnant does may lose all their embryos through intrauterine resorption. Shortly before giving birth, the doe will construct a separate burrow known as a "stop" or "stab", generally in an open field away from the main warren. These breeding burrows are typically a few feet long and are lined with grass and moss as well as fur plucked from the doe's belly. The breeding burrow protects the kittens from adult bucks as well as from predators.

The gestation period of the European rabbit is 30 days, with the sex ratio of male to female kittens tending to be 1:1. Greater maternal investment over male offspring may result in higher birth weights for bucks. Kittens born to the dominant buck and doe—who enjoy better nesting and feeding grounds—tend to grow larger and stronger and to become more dominant than kittens born to subordinate rabbits. It is not uncommon for European rabbits to mate again immediately after giving birth, with some specimens having been observed to nurse previous young whilst pregnant.

Female European rabbits nurse their kittens once a night, for only a few minutes. After suckling is complete, the doe seals the entrance to the stop with soil and vegetation. In its native Iberian and southern French range, European rabbit kittens have a growth rate of 5 grams (0.18 oz) per day, though such kittens in non-native ranges may grow 10 grams (0.35 oz) per day. Weight at birth is 30–35 grams (1.1–1.2 oz) and increases to 150–200 grams (5.3–7.1 oz) by 21–25 days, during the weaning period. European rabbit kittens are born blind, deaf, and nearly naked. The ears do not gain the power of motion until 10 days of age, and can be erected after 13. The eyes open 11 days after birth. At 18 days, the kittens begin to leave the burrow. Sexual maturity in bucks is attained at four months, while does can begin to breed at three to five months.

Burrowing behaviour
The European rabbit's burrows occur mostly on slopes and banks, where drainage is more efficient. The burrow entrances are typically 10–50 cm in diameter, and are easily recognisable by the bare earth at their mouths. Vegetation growth is prevented by the constant passing and repassing of the resident rabbits. Big burrows are complex excavations which may descend to depths of several feet. They are not constructed on any specified plan, and appear to be enlarged or improved as a result of the promiscuous activity of several generations. Digging is done by pulling the soil backwards with the forefeet and throwing it between the hind legs, which scatter the material with kicking motions. While most burrows are dug from the outside, some warrens feature holes dug from the inside which act as emergency exits when escaping from predators below ground. These holes usually descend perpendicularly to 3–4 feet, and their mouths lack the bare earth characteristic of burrow entrances. While kittens sleep in chambers lined with grass and fur, adults sleep on the bare earth, likely in order to prevent damp, with warmth being secured by huddling. Although both sexes dig, does do so more skillfully, and for longer periods.

Communication
The European rabbit is usually a silent animal, though it has at least two vocalisations. The most well known is a high treble scream or squeal. This distress call has been likened to the cry of a piglet. This sound is uttered when in extreme distress, such as being caught by a predator or trap. During the spring, bucks express contentment by emitting grunting sounds when approaching other rabbits. These grunts are similar to shrill hiccups, and are emitted with the mouth closed. Aggression is expressed with a low growl.
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