Can Spain Save the World's Most Endangered Cat?
Only about 150 Iberian lynx still survive in their native Spanish habitat, but a government breeding program is bringing new hope to the beleaguered species
Geoff Pingree and Lisa Abend
IF ANYONE KNOWS the Iberian lynx, it is Francisco Palomares. The 42-year-old Spanish biologist has, for the past 20 years, worked to protect the perilously endangered cat. He has designed spaces in the wild where the creature is more likely to survive, he has explored the causes of its drastic decline, and he has published enough scientific studies on it to qualify as a recognized world expert.
Yet during a study of the lynx's reproductive habits that he began more than a decade ago, Palomares and his team observed something they could not explain: In most litters, within the first three months following birth, one of the kittens simply disappeared. The mystery's solution might prove crucial to the survival of the world's most endangered feline, yet for all of his expertise, Palomares could not figure out why these kitten deaths occurred. It took an unprecedented triumph, followed by tragedy, to suggest the surprising answer.
Early last century, roughly 100,000 lynx roamed the Iberian Peninsula. Smaller than their Eurasian and Canadian counterparts, they moved between wooded areas and Mediterranean scrubland, hunting for rabbits, their primary food. But in the 1950s, a French pediatrician introduced myxomatosis, a disease deadly to rabbits, into his garden to control rabbit populations. The disease proved too effective, spreading through France and crossing the Pyrenees into Spain. It drastically reduced the Spanish rabbit population, and that reduction in turn affected the lynx. Road construction through isolated scrublands that were the lynx's home also took a toll. "As recently as the 1990s, there were 1,000 lynx in Spain," says Minister of the Environment Cristina Narbona. "Now there are approximately 150." With its habitat reduced to two areas--Doñana National Park and the Sierra Morena--the cat's plight is so grim that last March the World Wildlife Fund predicted the species would be extinct within five years.
Palomares has spent a career fighting that extinction. After completing doctoral work at the Doñana Biological Station, one of Spain's primary research centers on the Iberian lynx, he stayed on as an investigator and, in the time since, has witnessed great change. "Twenty years ago, we were just trying to learn the basics of lynx biology and ecology--diet, dispersal, how they used space," Palomares says. "Today, we are applying what we know to plan projects that will actually protect the lynx."
In one such project, Palomares and his colleagues in 2000 reintroduced rabbits into lynx-populated areas. Funded by the European Union's Project LIFE, which helps finance environmental initiatives on the continent, the scientists created 24 rabbit-protection sites, each 12 acres in size. Half the sites were fenced, and all offered artificial burrows for 1,200 vaccinated rabbits that the scientists introduced to help the animals repopulate. So far, rabbit survival has improved, but Palomares says that the experiment's success will not be clear for another three to five years.
As they initiated the rabbit project, Palomares and his associates were finishing their study of lynx reproduction. Starting in 1991, they had begun using radio and photo traps to track the breeding habits of several female lynx within a limited area of the Doñana park. The study yielded several important discoveries, among them that female lynx with sufficient territory bred annually, that they generally gave birth in March and that they usually delivered litters of three kittens.
But accompanying these useful findings was the troubling enigma of the disappearing kittens. Once, researchers found a 5-week-old kitten with two legs destroyed in what the scientists suspected was an attack by an immature lynx, but they found no remains of any of the other missing young. With the cat's population dwindling annually, understanding why one in three Iberian lynx kittens regularly went missing seemed vital.
Without physical remains to test, Palomares and his team searched for other kinds of evidence. They measured the rabbit population when litters were born and again 10 months later, but they saw no correlation between the amount of food available and the disappearances of kittens. Neither the size nor gender of the kittens seemed to play a role either--the missing kittens included both the largest and smallest members of litters. When the results of Palomares' study were published in Biological Conservation in March 2005, the author and his colleagues could admit only that they were stumped.
That same month, however, in the same Doñana park, something unprecedented occurred that would change everything. The story begins in 2003, when the staff of the Acebuche Center, a research station that cares for the park's endangered species, initiated a lynx captive-breeding program. Led by Astrid Vargas, a Spanish conservation biologist, the scientists knew that previous attempts to breed lynx in captivity had failed, so they tried a simple approach: Intervene as little as possible.
To that end, the center staff not only built artificial habitats to match the cats' natural homes but mounted 24 video cameras in the breeding areas so the scientists could observe the lynx closely while remaining physically distant. After grouping the cats--two as a monogamous couple, three others in a polygynous arrangement--the scientists waited and watched.
Late in January 2005, cameras recorded one male, Garfio, mating with Saliega and Esperanza, the females in his group. Researchers had observed lynx copulating in previous breeding attempts, but the females had never actually gestated, so the scientists now had to wait and see if either Saliega or Esperanza was indeed pregnant. By anesthetizing either female, the team could have ascertained a pregnancy much earlier, but Vargas--fully committed to nonintervention--drew the line. Instead, the team accustomed the females to walking through a Plexiglass tunnel in which the scientists were able to x-ray the cats without even touching them. The x-rays showed that Saliega was carrying at least three kittens.
Sixty-four days after she was recorded mating with Garfio, Saliega gave birth. The first Iberian lynx born in captivity, her three kittens marked a triumph for the Acebuche Center and for conservationists throughout the country. The kittens became instant celebrities across Spain, even though Vargas and her team remained committed to their hands-off policy: Not until April 21 did they venture close enough to identify the newborns' sex and give them names: Brezo, Brecina and Brisa.
Aware that 50 percent of first-time lynx mothers eat their young, Vargas remained watchful. Her worries soon seemed misplaced. "From the beginning," she says, "Sali was an expert mother." But after the early good luck of the pregnancy and births, misfortune struck. Just six weeks after they were born, the male kitten, Brezo, killed the female Brecina in a fight. "It was completely unexpected," Vargas says. "We had no idea that the lynx cubs would even fight, let alone kill each other. When the fight broke out, the mother tried to separate them. But this was her first birth, and she didn't know how to do it."
The violent episode sent team members searching--by phone, mail and Internet--for an explanation. "We sounded a voice of alarm the day of the fight," says Vargas, who recalls that the first clue came from Russian scientist Sergei Naidenko, who had spent 15 years investigating aggression among boreal lynx kittens. "He had observed that in 100 percent of boreal lynx litters the siblings fight among themselves and that 50 percent of these fights result in injuries, including death." Naidenko had published his work only in Russian, so it was largely unknown to European and American scientists. "To contact this man was a revelation," Vargas says.
According to Naidenko, lynx siblings kill each other during a distinct period--"always between the 30th and 60th day of life," Vargas says. "And the peak of aggression is day 45. Our litter was 44 days old when this happened."
This finding squared with Palomares' observation that among lynxes in the wild, kittens always disappear before they reach three months. And Vargas' attempts to rule out other causes of aggression likewise matched Palomares' discoveries. "Our cubs were putting on about 35 grams of weight per day, and their growth had not slowed, so it's not like they were getting hungry or growing less," Vargas says. "There was no demand in their physiology." Palomares had reached the same conclusion. "We compared the size of rabbit populations with the timing of the births," he explains. "There was no correlation between the amount of available food and the cubs' deaths."
For all its bitter surprise, then, Brezo's murder of Brecina provided valuable knowledge. "We could not conceive that a littermate would attack another littermate," Vargas says. "That was too brutal. We thought these were special cases, having nothing to do with normal biology. But this enabled us to put together a lot of pieces of the puzzle and realize that this was in fact a biological reality for the Iberian lynx."
Palomares agrees that this unfortunate event was important. "What happened at Acebuche cannot totally confirm that cub disappearances in the wild prior to three months of age are always due to fights among siblings," he says, "but it seems very likely that in the majority of incidents, that is indeed the case."
For now, a lynx kitten's reasons for killing a littermate remain unknown. Some scientists speculate that the kittens' aggression is related to the release of hormones that occurs when their diet changes from mother's milk to meat. Vargas herself wonders if "it could be related to hierarchy among the cubs. The male killed the female, but she was the largest of the three. Maybe the male saw a competitor in her."
Whatever the reason, the discovery that violence among littermates likely occurs naturally has removed one worry from a long list that conservationists like Palomares face as they attempt to save the Iberian lynx. Yet time may be the greatest worry of all. "Right now, there are a lot of different projects under way, but we need some time to see how the lynx respond," Palomares says. "If in five years the lynx population is stable or growing, then I think we can be optimistic about its prospects."
Journalists Geoff Pingree and Lisa Abend live in Madrid.