The Iberian lynx Lynx pardinus, one the worlds most endangered cat species, is doing better. Not well, but better. There are now 309 lynx (85 breeding females) living in four populations compared to 94 (with only 27 breeding females) in two populations in 2002. And the four conservation breeding centres in Spain and Portugal now host a total of 77 mature individuals. The first Iberian lynx was born in captivity only 2005. Experiences in the Guadalmellato and Guarrizas study areas have demonstrated that both, wild-to-wild translocation and the release of captive born lynx are appropriate methods for bringing the Iberian lynx back to where it once roamed. And suddenly, problem No. One is no longer the lince, but the conejo, the common rabbit Oryctolagus cuniculus, the lynx most important prey species. The frantic search for the rabbit has been launched. We have enough lynx to be released and we know how to reintroduce them but where are the rabbits that can support at least a small lynx population?
The meeting of all partners of the IberLince Life Project in Moura, Portugal, on 2021 May 2013 was dedicated to this question. The project teams from Portugal and from the Spanish provinces of Andalucía, Extremadura and Castilla la Mancha presented their ideas for suitable release areas. The criteria to select an area were (1) habitat quality (dens cover habitat, e.g. Mediterranean hard shrub), (2) size of the habitat patch (at least 10,000 ha or space for 50 lynx), (3) sufficient prey base (spring density of ≥2 rabbits/ha), and (4) connectivity to neighbouring potential lynx subpopulation with a distance of maximum 42 km. This last criterion aimed to secure that animals dispersing from a new nucleus would not be lost, but would have a certain chance to find another population. The first phase of the recovery strategy foresees to create a metapopulation along the Sierra Morena from the remnant population near Andújar towards Portugal in the west. However, it soon turned out that not many release area would meet all criteria and that the idea to create a chain of pearls along the Sierra Morena simply lacks sufficient spots with high rabbit densities. Hence the strategy or at least the priorities for the next years needs to be adapted to the availability of rabbits. All sites with decent rabbit populations within the project area in the southern half of the Iberian Peninsula will now be assessed for their potential to host a small lynx population. Most of the seven sites favoured so far are still within or adjacent to the Sierra Morena, but there was a consensus at the meeting to also consider release sites in Monfragüe (northern Extremadura) and in the Montes de Toledo (northern Castilla La Mancha).
Isnt it ironic: The rabbit, introduced to many areas across the world, often with devastating consequences for the local biodiversity, domesticated and bred by the millions to feed people, is a major conservation problem at its place of origin, the Iberian Peninsula. There are two subspecies, the northern O. c. cuniculus (the one that was domesticated and known world-wide as a pest species), and the southern O. c. algirus. This southern subspecies is more threatened (with an estimated decline of 95% in the second half of the 20th century), suffers more from diseases like Myxomatosis or Rabbit Haemorrhagic Disease and is the main food not only for the Iberian lynx but also for other threatened species such as the Spanish imperial eagle Aquila adalberti.
Although the research on rabbits and their diseases have considerably increased in recent years, we know relatively little about this keystone species. The population decline is estimated from studies in a few areas, the dynamics of the populations and the epizootics are not understood, and for many areas with suitable habitat for lynx, but no rabbits, we do not know why and for how long the rabbits are gone if they ever were there. The rabbit was for a long time simply not a species worth to be considered, leave alone studied.
Prey decline is known to be a major threat to the survival of large cats. Shortage of prey is most often the underlying reason for the collapse of cats depending on ungulate prey. Even Panthera species can stand a rather strong persecution as long as there is sufficient prey. Exceptions from this rule one is e.g. mentioned on page 18 of this issue concern most often small and isolated, hence highly vulnerable populations. The Iberian lynx seems to be a special case among the medium-sized cats. We generally assume that prey supply is sufficient for the lesser cat that hunt small or medium-sized prey, rodents, birds, or lagomorphs. But how much do we really know about the feeding ecology and about the availability of prey of the small and medium-sized cats? Clearly not enough to be reassuring!
(IUCN/SCC)