Former President Clinton and his daughter Chelsea visit the school garden of Farasi Lane primary school on May 1 in Nairobi. The Clintons on May 3 visited an elephant sanctuary during a multi-day tour of Clinton Foundation projects in Africa. (Njue Murimi/AFP/Getty Images)

Former President Bill Clinton and his daughter, Chelsea, visited one of Africa’s most prominent elephant reserves Sunday, highlighting the enormous threat still facing the species, in spite of growing conservation efforts.

In a separate visit, Secretary of State John F. Kerry headed Sunday for an elephant sanctuary elsewhere in the country. He is in Kenya for talks on counterterrorism and regional security issues but has also been a strong proponent of combatting poaching.

The Clintons have become some of the world’s best-known advocates for the elephants in recent years, as demand for ivory in Asia has led to a surge in poaching across Africa. About 100,000 of the continent’s elephants were killed for their tusks between 2010 and 2012. That trend appears to be continuing across some of Africa’s war-ravaged countries, with poaching groups often linked to criminal and terrorist networks.

As secretary of state, Hillary Rodham Clinton hosted a conference on the need to end poaching, calling for a concerted effort to protect elephants and for increased law enforcement. In 2013, the Clinton Global Initiative, part of her family’s charitable foundation, announced an $80 million program to protect Africa’s elephants and end ivory trafficking, in coordination with several conservation groups.

On Sunday, it was Chelsea Clinton pressing for aid, touring the Samburu National Reserve in northern Kenya, the jeep she was in getting within feet of an elephant herd in this park that many consider a conservation success story.

“My mom and I both realized independently that we were facing a real poaching crisis,” said Clinton, who is vice chair of the Clinton Foundation, which her mother joined after stepping down as secretary of state in 2013. “We knew we had to do something.”

Experts call the Clintons’ attention to the issue — particularly Hillary Clinton’s speech in 2012 as secretary of state — a galvanizing force.

“It was a real tipping point,” said Iain Douglas-Hamilton, founder of Save the Elephants, a nonprofit organization. “Her language was very powerful.”

The increased attention to the issue has helped conservation advocates in some places, including Samburu, to tap into funding sources and access cutting-edge anti-poaching research. But in many other locales, the situation continues to be grave.

In war-torn Central African Republic, for example, fledgling anti-poaching efforts have done little to diminish the problem. In Congo, 30 elephants were killed in 15 days this year in Garamba National Park. In Congo, the rebel Lord’s Resistance Army, led by Joseph Kony, has been involved in ivory trafficking, according to experts.

The number of elephants killed in 2014 has not yet been released, but it’s expected to be close to the 20,000 slain the previous year. The staggering numbers of deaths are occurring despite campaigns by nongovernmental organizations such as the Clinton Foundation and global accords such as the London declaration, in which 46 countries agreed to help curb the illegal wildlife trade.

Central Africa’s forest elephants have proved to be especially vulnerable. Between 2002 and 2013, 65 percent of the species was killed, according to a study in the journal PLOS One.

“We are in an elephant crisis right now,” Hamilton told Bill and Chelsea Clinton and the delegation of donors who came with them to Samburu.

Ivory tusks are worth about a thousand dollars a pound in China, and demand there continues to drive poaching across Africa. The illegal wildlife trade is valued at $7 billion to $10 billion annually.

Even in Kenya, where the government is considered to be one of the most vehement foes of poaching in Africa, only a fraction of those charged with the offense are ever sentenced to prison.

In Samburu, about 90 elephants wear GPS collars that tell researchers when the animals are stationary — and possibly wounded by poachers — or running quickly, possibly through a zone threatened by poachers. The Clinton Foundation doesn’t directly fund the project, or others like it, but it has helped connect Samburu-based Save the Elephants with other donors.

Chelsea Clinton said she wasn’t entirely sure what drew her interest to the issue initially — whether it was seeing elephants in the Ringling Bros. and Barnum & Bailey Circus or at the zoo in Little Rock, where she lived as a child — but “there was a real emotional connection, and I knew that I wanted to engage in elephant conservation efforts.”

“This we really know how to solve,” she said. “It’s just that the organizations that are here on the front lines . . . need more money to do what they’re doing.”

Coincidentally, Hillary Clinton’s successor as secretary of state, Kerry, was also in Kenya on Sunday, arriving from Sri Lanka for a series of meetings Monday with President Uhuru Kenyatta and other senior officials.

Kerry and his entourage drove through Nairobi National Park, pausing to gaze at lions, buffalos, warthogs, giraffes and gazelles, while en route to the Sheldrick center elephant orphanage. There, Kerry helped feed one infant animal and listened empathetically to the stories of how the young elephants had arrived. Some were taken in after their tails were bitten off by predators, and others suffered swollen feet from being mangled in cables. In some cases, the animals simply wandered away from the herds.

The elephants are nursed back to health until they reach 3 years of age, when they are returned to the wild.

In his previous job as chairman of the Senate Foreign Relations Committee, Kerry held the panel’s first hearing on poaching in Africa, urging greater action to save endangered elephants.

Carol Morello in Nairobi contributed to this report.