YOSEMITE NATIONAL PARK - On the easternmost edge of this expanse of glacial granite, far from tourist haunts, a tiny lamb rams his mother's udder then flutters its tail when milk starts to flow.
California biologists watching through spotting scopes take note, for this is no ordinary baby and this treacherous sheet of talus rock at 8,000-feet elevation is not particularly safe, even for a creature as sure-footed as his mother.
On this day they'll count him as part of the precarious population of Sierra-Nevada Bighorn Sheep, at 400 one of the most endangered big mammals in the U.S. But they know the odds are 75 percent against this little guy reaching adulthood: rockslides, avalanches, disease and mountain lions all stand in the way.
"This was a harsh winter and we've been anxious to see how they'd do," said Thomas Stephenson, the senior environmental scientist with the Sierra Nevada Bighorn Sheep Recovery Program from his perch in Lundy Canyon in the eastern Sierra Nevada.
For a decade California and federal biologists have helped the species by removing the obstacles they could: disease-carrying domestic sheep were banned from Bighorn Sheep territory two years ago and trappers hunted, snared and collared mountain lions suspected of being a threat.
But saving Bighorn Sheep by harming mountain lions is creating new controversy within the sheep recovery project and it pits an endangered species against one that received special protections by California voters in 1990.
Late last year one of the four program biologists filed a formal complaint about an increase in mountain lion hunting since 2007 prompted by a spike in sheep deaths. It resulted in tense office discussions and, eventually, a ruling favorable to lions this winter from the state Legislative Counsel.
"We have to look at the whole ecosystem and not treat the sheep like they're in a captive breeding program," said Becky Pierce, the associate wildlife biologist and cougar expert who filed the complaint.
A lion proven to kill endangered bighorns can be shot. But the ruling now forbids snaring to collar a lion to track its movements or even capture a killer, and it is altering the recovery program as scientists search for answers on how to protect the sheep while keeping the balance of nature.
"It's so easy to say, 'we'll just take out as many as we can in their range' when the bigger issue" - getting sheep to live alongside their main predator - "will ultimately provide the most benefit," said Stephanie Boyles, wildlife scientist with the Humane Society of the United States.
"It's a good question for a college class," said Stephenson, of the California Department of Fish and Game. "Ask them if it's OK to kill mountain lions and they'll say 'no.' But ask them if it's the only way to preserve the species and get them back into Yosemite National Park and their other historic ranges, and they might say 'yes."'
Sierra Nevada Bighorn Sheep, with horns that splay sideways, are related to the classic Desert Bighorns whose circular horns are like the icons on Dodge trucks and Rams football helmets. There never were very many- maybe 1,000 scattered since prehistoric times in a dozen herds across the alpine eastern Sierra.
But settlers brought guns and, worse, domestic sheep and the numbers quickly dwindled. By 1999, when Sierra Nevada Bighorn Sheep were federally listed as endangered, they numbered 114. Today, due to intensive management, there are 400 in eight of the 12 remote areas optimum for their long-term survival, two-thirds of the program's population goal.
They are a sight to behold, traveling in herds across icy tundra in California's most extreme terrain, scampering over boulders to elude predators, delighting the few humans who cross their paths.
"It was the highlight of our Audubon bird walk and they aren't even birds," said Dave Marquart, who recently saw five in Lundy Canyon near Lee Vining.
The aim of the $600,000-a-year management plan is to increase the number of females older than one year from the current 200 to 305, possibly by 2017. Then the sheep would fend alone, theoretically able to reproduce at numbers high enough to withstand predation.
"A whole host of species depend on the Sierra Nevada Bighorn Sheep for their existence," Stephenson said. "Some say the wolverine disappeared from the Sierra Nevada alpine environment when the sheep declined."
Over the past decade, trappers have killed 23 mountain lions, which number about 5,000 statewide. The cats have eaten at least 59 sheep.
Over the same period 1,079 lions have been killed for things such as attacking or threatening livestock and pets.
"We don't intend to manage mountain lions indefinitely," Stephenson said. "We just want to get to our recovery goals."
Numbers and timelines shouldn't be part of the equation, says Boyles. Sheep may recover more slowly if mountain lions continue to attack them, she acknowledges, but at least those that do survive will grow up fearing the big cats.
But a potentially slower recovery, Stephenson says, increases the chance that a smaller population could be killed off by disease or some other catastrophe.
The current dispute has prompted the program to now take a closer look at how it handles mountain lions and when it kills them and develop a written policy. Even whistleblower Pierce thinks the ban on trapping lions to place collars on them goes too far.
Now if a lion kills a sheep, then it is fair game. But those that threaten sheep, or are suspected of killing a sheep, or just like hanging out in their territory now trigger all sorts of discussions, including concerns over the loss of a tool used to monitor them.
"If we don't need to be managing lions, then we shouldn't be," Stephenson said. "But it can often come down to one lion taking sheep that we're not even aware of."