Wednesday, January 07, 2009

Iberian lynx survival dependent on rabbit recovery

Lynx Survival Dependent on Rabbit Recovery

By Dennis G. Rainey, World Coin News
January 06, 2009

What species, according to many, in the cat family (Felidae) is critically endangered of becoming extinct? It is the first feline species to have this status. If it does become extinct it will be the only feline species to do so since the saber-toothed tiger disappeared 10,000 years ago, excluding one geographic variety (subspecies) of lion and three subspecies of tigers.

The species is the Iberian lynx (Lynx pardindus), sometimes called the Spanish lynx. It is depicted on the 2004 Cuba 10 pesos (KM 802), but it does not occur naturally in Cuba.

What does this lynx look like? Males stand about two feet high at the shoulder and weigh an average of 27.5 pounds. Females are smaller. They have prominent grayish leopard-like spotted fur, short tails tipped with black and a flared facial ruff. Their ears have long black tufts.

Its habitat requirement is a mosaic of forest scrub for cover (25 to 35 percent bush cover) and grass for the rabbits it specializes in eating.

Archeologists have found that this lynx was present 4500-1100 B.P. in moderate numbers throughout the Iberian Peninsula. It is always in close association with the European rabbit (Oryctolagus cuniculus), which, at certain times of the year, makes up 90 to 100 percent of the lynx's diet and 80 to 85 percent at other times. However, they can eat other prey. As one author said, "where there are no rabbits there are no lynx."

It is estimated that there were 100,000 Iberian lynx living on the peninsula in 1900, and by 1960 the species still occupied 23,166 square miles. In the 1980s the population dropped to around 1,000 and covered only 4,131 square miles.

The remaining lynx now live in Spain in just two groups of about 135 breeding adults that occupy a total of just 46.33 square miles. These groups are separated from each other by 125 miles. One group of about 35 adults (with five to eight breeding females) lives in Doñana. The other lives in Andújar-Cardeña with 100 adults, of which 20 are breeding females. Both sites are in Andalusia in southern Spain.

There may be a few scattered individuals elsewhere in Spain and even in Portugal, but these numbers are unknown and probably consist of non-breeding animals that will not survive.

What caused the Iberian lynx's decline? Three factors are involved: hunting and road kills by automobiles; habitat loss and fragmentation; and loss of primary prey, i.e., rabbits.

Historically, hunting by humans has been devastating. Until the mid-20th century lynx were killed as a game species for their pelts and as vermin, supposedly because they killed small game animals. Officials paid a bounty for them.

Lynx became legally protected in 1973 in Spain, but illegal hunting still continues. Also, many lynx - as many as 25 percent in some areas - were killed as a byproduct of non-selective predator and rabbit control measures with steel traps and snares. This was particularly hard on small populations.

There were few road kills until the 1980s when the speed increased and new roads were built in remaining lynx areas. Now it is an important mortality factor.

Large mammals require a suitable interconnected habitat that does not become fragmented. Fragmentation leads to group isolation and long-term genetic problems. Lynx in particular are sensitive to habitat loss because they are territorial and cannot move easily to a new distant area occupied by other lynx. Much of the forest-scrub has been lost due to the planting of non-native pine and eucalyptus plantations that lack a bushy understory and proper rabbit habitat.

An unintended consequence is that eucalyptus are prone to forest fires and lower the water table, reducing the plants rabbits feed upon. The most recent serious factor in the Iberian lynx's decline was the loss of prey - rabbits.

According to one reference, the name España means "land of the rabbits." The same reference stated that the European rabbit originated in Iberia. This rabbit is an integral part of the Spanish forest-scrub-grass ecosystem, and if that habitat changes to something different and rabbits disappear it is almost impossible to bring them back into that changed habitat, thus spelling doom for rabbits and lynx. This nearly happened and may still occur.

In 1952 a bacteriologist in France inoculated two rabbits with the myxomatosis virus and released them into his vegetable garden to control the rabbit pests. This disease is caused by the myxoma virus and is deadly to rabbits. It is spread by fleas and mosquitoes. By 1954 90 percent of rabbits in France had died, and by 1955 95 percent had died in the United Kingdom.

The disease spread quickly throughout Europe and killed most of the rabbits in the Iberian Peninsula. The lynx faced starvation and many died. The remaining rabbits that developed resistance do what they do best  they increased in the 1980s.

Unbelievably, in 1988 another virus producing Viral Haemorrhagic Pneumonia (VHP) was introduced, and by 1991 it had killed 70 to 90 percent of the rabbits in Spain. The rabbit death rate from VHP has slowly fallen and is now around 30 percent, but myxomatosis is also still present. Both diseases cycle unpredictably, dependent on weather patterns. As few as 5 percent of the rabbits present 50 years ago remain today.

In Spain remaining rabbits are under great stress from several sources: pressure from other natural predators (some 39 species); unwise rabbit hunting conducted during breeding season; artificially high deer and boar populations that compete with rabbits for food, solely to placate big game hunters; habitat loss; and livestock overgrazing. Rabbits have not recovered in Spain as they have in other places in Europe.

Several projects are underway in Spain to try to aid rabbit recovery. These include captive breeding programs, translocations, reintroductions and vaccinations of released rabbits. Initial reintroductions did not work because of poor planning and lack of protection for the rabbits, which rapidly disappeared. Later, rabbits were released in fenced areas that allowed lynx to enter but kept out other predators such as foxes. It provided them with safe breeding dens and shelter. Initially they were artificially fed.

However, several important obstacles are in the way. There is almost a total lack of knowledge about how all of the rabbit's predators are interacting to hold back their recovery. There is not enough basic knowledge about what drives the two diseases, and there is no effective way to control them. Vaccinations last only three to six months and are not passed between rabbits. Thus, rabbit recovery is not going to happen anytime soon.

Supplemental feeding programs have been started at both Doñana and Andujar.The lynx are fed domestic rabbits, chickens and carrion. Fences around the food keep other predators out. This, of course, is only a temporary fix in the hope that a more effective tactic will be discovered.

Translocations and reintroductions in Spain are possibilities for lynx recovery, but it poses great problems. To acquire suitable subjects for translocations and reintroductions, the two existing groups must be stabilized and expanded considerably. For reintroductions, a captive breeding program involving several centers outside Andalusia should be established. Of course, these will be extremely difficult to accomplish.

A Nov. 12, 2007, press release from the Portuguese Secretary of State for the Environment announced a national action plan for the conservation of the lynx in Portugal. It outlines a five-point plan that includes preserving lynx and rabbit habitat, minimizing non-natural mortality, implementing a captive breeding program, increasing public social awareness of the lynx's plight and establishing an ongoing monitoring system for the lynx.

Check out the Web site of SOS Lynx.org at www.soslynx.org/.

Questions and comments are welcomed. Contact me at http://www.iberianature.com/index.html.

Ward, D. The Iberian Lynx Emergency. 2003. http://www.carolinelucasmep.org.uk/interests/pdf/lynxreport_26042004.pdf.

http://www.numismaster.com/ta/numis/Article.jsp?ad=article&ArticleId=6002

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Learn more about big cats and Big Cat Rescue at http://www.bigcatrescue.org

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