Rabbit abundance is the essential component of Iberian Lynx habitat. Lynx are restricted to habitats where there is potential for rabbits to thrive, and prefers those with a suitable structure for stalking prey (Palomares 2001, Ferreras et al. 2024). Adult females do not breed in locations with low rabbit abundance and tend to avoid them for establishing their home ranges. A threshold rabbit density estimated at about five rabbits/ha in springtime (Palomares et al. 2001) is associated with most instances of successful reproduction. Monitoring protocols use a proxy for this threshold at about 15 rabbit latrines/km. Conditioned to holding enough prey, suitable habitats include (i) Mediterranean forest and scrubland with an open structure, (ii) rangelands with scattered oaks (a widespread land use called ‘dehesa’ in Spanish; ‘montado’ in Portuguese) with an understory of sparse woody vegetation, (iii) mosaics of scrubland and pastureland, and (iv) agricultural mosaics of cultivated land and scattered patches of dense woody vegetation (Gastón et al. 2016, Garrote et al. 2017). Continuous open farmland, big game estates, extensive livestock husbandry at high densities, and forestry are land uses generally avoided by lynx. Moderate levels of human activity may be tolerated if other habitat components are favourable. Areas with high levels of human activity may not be avoided if they contain suitable habitat, but may act as demographic sinks due to increased risk of lynx mortality through road casualties, predator control and pathogen transmission from domestic animals.

The Iberian Lynx is endemic to the southern Iberian Peninsula, where it occurs in Spain and Portugal. In 2022, within Spain, it occurred in the regions of Andalucía, Castilla-La Mancha and Extremadura. Within Portugal, it occurred in the regions of Alentejo and Algarve. During the last two decades, distribution maps of the Iberian Lynx have been published on a yearly basis together with estimates of population size (Life+ Iberlince 2017, Sarmento 2022, Life Lynxconnect 2023). These maps are available at the websites www.iberlince.eu and lifelynxconnect.eu. Unpublished information on the estimated location of the home ranges of breeding females was used to complement the basic information contained in the maps, which were reinterpreted before outlining the area of occupancy (AOO).

In 2022, the Iberian Lynx geographic range consisted of 50 spatially discrete nuclei which were grouped into five biologically meaningful subpopulations according to their relative rate of demographic exchange, either documented or estimated. In other words, nuclei within each subpopulation were more likely connected through metapopulation dynamics than nuclei assigned to different subpopulations. The subpopulation with the largest area was Sierra Morena, composed of 24 nuclei and contributing 42% of total AOO, followed in size by Doñana (10 discrete nuclei, 18% of AOO), Toledo Mountains (seven nuclei, 17% of AOO), Vale do Guadiana (five nuclei, 14% of AOO), and Matachel (fournuclei, 9% of AOO).

Lynx nuclei have been arranged into clusters within some subpopulations, reflecting the history of lynx recovery, management units, administrative boundaries, and discontinuities associated with geographical accidents. Clusters have traditionally been given specific names. This alternative nomenclature is reported to facilitate the identification of lynx nuclei in previous Red List assessments and, especially, in original data sources of the European Union LIFE projects. Clusters in Sierra Morena include Andújar-Cardeña, Guadalmellato, Guarrizas, Campo de Montiel, Guadalmez, Sierra Norte, and (provisionally) a small nucleus in the Subbetic Mountains. Likewise, Toledo Mountains include the large Western Toledo Mountains cluster and a small, demographically connected nucleus called Valdecañas, located 75 km westwards in the Tagus River valley.  

Distances between subpopulations were in the range of 61–280 km. The range of distances to the nearest subpopulation (61–97 km) was within distances associated with long dispersal events (e.g. Sarmento et al. 2014), but with separation between subpopulations was larger than mean or modal distances for exploratory movements and natal dispersal (Ferreras et al. 2004, Rueda et al. 2021). Subpopulations were often separated by hard barriers made of low-quality or unsuitable habitat in terms of food availability.

Additional non-resident adult lynxes are often detected in areas where occupancy was not considered stable and were not computed as AOO. These areas, used by adult or subadult floaters, were identified through tracking of collared individuals involved in dispersal or through detection by local observers and subsequent confirmatory surveys. Long-distance movements and lynx exchange are frequently documented between the subpopulations that are monitored. Therefore, the number of new temporary settlements resulting from dispersal is probably underestimated, unless these colonisation attempts become eventually successful. Areas subject to incipient reintroduction attempts are included in this class and therefore also excluded from the distribution map. In 2022, the total area outside AOO where occasional breeding, floater presence, or dispersal were detected or assumed to occur amounted to 2,592 km².

Actions currently in place

The following conservation actions are undertaken to preserve consolidated subpopulations, and to stabilise reintroduced or naturally colonised lynx nuclei.
 
Monitoring plays a key role. Every year, considerable effort is made to recapture in camera traps as many individuals as possible. Spot patterns in the lynx coat allow individual identification. Breeding territories are geolocated and an important goal is determining whether reproduction takes place in them. Immigrants are tried to be detected and identified. Some individuals are tagged with radio-collars to obtain valuable data on mortality rates and movements. The relative abundance of rabbits is also regularly assessed. All known mortality events are recorded and investigated. Intensive field work allows the detection of local threats associated with habitat alteration and hazards for specific individuals. The effect of implemented conservation actions is evaluated. A network of collaborators built over the years has proven useful to get information relevant for conservation. Intensive monitoring is a trace of the procedures implemented in the early 2000s (Simón 2012), when the fate of each individual was highly relevant for species survival. With a rapidly expanding lynx population, maintaining such an effort is becoming unsustainable, and a design adapted to the new circumstances is needed.

Habitat management protocols, including guidelines for the recreation of a patchy structure of vegetation and rabbit restocking, are still be implemented in some localities, but the mid-term sustainability of habitat quality relies on the commitment of landowners and gamekeepers to keep on applying lynx-friendly management procedures. This important action has been inherited from conservation agreements in private lands signed during the last 20 years. Such agreements often involved some sort of technical support or economic compensation, but favourable habitat management has often continued after the reduction or even the absence of incentives. Informative campaigns have also increased the awareness of local communities about the benefits of lynx occurrence for ecosystems and their own livelihoods. Lynx conservation has considerable social support which is maintained by regular communication of relevant news to the general public.

After reintroduction is completed, even in scenarios where newly created nuclei show signs of self-sustainable growth, additional lynxes are sometimes restocked to fill gaps in the local distribution, to help balance adult sex-ratios, or to replace losses in sites of interest.    

Where needed, habitat management is also applied to stepping stones, that is, relatively small areas selected in the intervening space between existing subpopulations, meant to facilitate transitory occupancy of dispersing lynx and eventually demographic exchange. Stepping stones are initially selected on the basis of habitat models. In some subpopulations, lynx productivity is high enough to produce many emigrants, some of which discover and colonise suitable areas. After detection of lynx presence, such areas may be defined as stepping stones. Management in these areas includes deeper monitoring, a survey of mortality risk, an assessment of the area containing enough food, contacts with landowners to create a receptive environment, and prospective lynx releases.

In stable lynx nuclei, recent reintroduction sites, and stepping stones, non-natural mortality is monitored and measures are actively taken to reduce mortality rates. The mere presence of conservation technicians and their informative talks may suffice to reduce the risk of lynx losses, especially from hunting and predator control. In most locations, any conflict from predation on domestic animals is promptly addressed and compensated. Economic support is supplied to farmers to adopt measures preventing lynx to access poultry pens. Individual lynx recurrently involved in livestock predation may be captured and translocated. Irrigation ponds and wells are inventoried in lynx areas, drowning hazards are evaluated while fencing may be reinforced and escape devices can be installed in the most dangerous spots. Hunting fences are also checked to avoid lynx entanglement. Road kill prevention includes the detection of risky situations (e.g. black spots) and the implementation of measures to increase the permeability of transport infrastructures (underpasses, overpasses, culverts, and devices channelling lynx movement), to increase mutual detection between lynxes and drivers (right-of-way clearings, visual and acoustic deterrents), to calm traffic (speed limitation, bumps), and to increase safety in high-speed roads or railways (efficient fencing combined with the construction or rehabilitation of safe passages). Mortality rates due to natural causes are also minimised especially by sanitary checks to determine the circulation of pathogens in lynx subpopulations and the fraction of individuals that actually develop a disease. Annual health checks help to prevent disease outbreaks that have proven highly detrimental for lynx conservation in the past.

The genetic composition of each subpopulation (and clusters within subpopulations) is also monitored through the accumulation of biological samples collected during sanitary checks and from lynx found dead. The genetic composition of the ex situ population is also known (Kleinman-Ruiz et al. 2019). Both sources of information are combined to maximise genetic diversity within lynx nuclei and clusters. Genetic criteria are established to (i) prioritise access to breeding in the captive population, (ii) to design mating schemes, (iii) to select founders for reintroduction, (iv) to select lynx for restocking, (v) to extract individuals from the wild that could improve genetic diversity of the ex-situ population, and (vi) to inform translocations between populations.   

To create new subpopulations through reintroduction, conservation actions include a thorough evaluation of the suitability of the reintroduction site using criteria as size, quality and landscape connectivity of habitat patches, mortality risks, legal protection, rabbit abundance, land use, health parameters of co-occurring wildlife, road density, or social attitudes, among others. The proper assessment of an area for reintroduction may take several years of data collection and analysis. Releases of 4–10 individuals per year are usually sustained for four to six years to cope with the risk of high emigration rates during the first attempts. Occasional restocking may be applied later on, if needed. After that, the regular management described above is applied.

The Iberian Lynx is listed in Appendix II of the Bern Convention, and Annexes II* and IV of the European Union Habitats and Species Directive. It is also listed in Appendix I of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES).

Actions needed to mitigate major threats

The most reasonable strategy to buffer the effects of a potentially sudden rabbit population collapse on the lynx population is spreading the risk by creating as many reintroduced populations as possible. Ideally, this should be done during the current phase of generalised abundance of wild rabbits. This strategy relies on the assumption that a new outbreak would take some time to spread at a large scale, but this depends on the speed of pathogen transmission and how rabbit abundance is geographically distributed when the outbreak takes place. Early detection is essential to try to isolate the outbreak. Current plans consider monitoring rabbit abundance as an indicator, using specific abundance thresholds as a warning. Monitoring rabbit pathogens could also be useful and it is being planned. The reaction to a sudden decrease in rabbit density mainly relies on mitigation measures such as rabbit restocking and supplementary feeding. This conservation response might work during an intense but transitory reduction of food availability. However, in most cases, predicting how long it will take for rabbit populations to recover from an emerging disease will be difficult.

More generally, increasing artificially the abundance of rabbit populations at a large scale is costly and has proved largely inefficient. It may pay moving lynx to more rabbit-rich areas if they exist. This action would mimic the ability of lynx to track prey across the landscape. Indeed, the selection of stepping stones aimed to facilitate connection between existing subpopulations has been, in most cases, actually made by lynxes themselves, reaching and pointing out sites meeting the ecological conditions suitable for establishment. Essentially, moving lynx where rabbits thrive instead of increasing rabbit abundance within occupied areas with low lynx productivity has been the successful approach followed during the selection of areas suitable for reintroduction and the subsequent releases.

Regarding the question of where to undertake new lynx introductions, currently suitable habitat seems to abound. A trade-off exists between the advantages and disadvantages of spacing lynx subpopulations as much as possible. Broad spacing protects subpopulations from threats originated in distant subpopulations to spread and affect the others, and also reduces the exposure of the population to wildfires and other large-scale disturbance. On the other hand, spacing hampers demographic and genetic exchange. Increasing separation between subpopulations also reduces the probability of subpopulations to be rescued (Rodríguez and Delibes 2003), but that could be done artificially with new reintroductions or restocking. Two new reintroduction attempts in southeastern Spain have started in 2023, one of them in the Murcia region, 500 km apart from the western-most Portuguese subpopulation of Vale do Guadiana. A number of additional reintroductions in distant localities are also planned.

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