(CNN) -- The bodies of young elephants covered in the brown dirt of dried-up wells tell a heartrending story.
A baby elephant in the Gourma region of central Mali had been trapped in a well for three days.
Reaching desperately for drops of water, they had lowered their trunks, toppled in, remained trapped and died in Mali's scorching heat.
The "last desert elephants in West Africa" have "adapted to survive in the harsh conditions" they face, Save the Elephants said Monday. But now, the group says, conditions have gone from bad to worse, and they are living "on the margin of what is ecologically viable."
Save the Elephants distributed new pictures Monday that depict the devastating drought and the struggle for survival in Mali, one of the poorest nations in the world.
"Six elephants have already been found dead," the group wrote in a news release accompanying the photos.
"Four others, including three calves, were recently extracted from a shallow well into which they had fallen when searching for water. Only the largest survived."
The youngest are in the most danger, since their smaller trunks can't reach deep into the few remaining wells, the group said.
The worst drought in 26 years is threatening the existence of the "last desert elephants in West Africa," the northernmost herds in the continent, Save the Elephants said.
The animals, now numbering only about 350 to 450, have been called "the last elephants of Timbuktu," said Jake Wall, a scientist with Save the Elephants. But they're south of Timbuktu, Wall told CNN in a phone interview from Bamako, Mali. "We tend to refer to them as 'the last Sahelian elephants.' " See a map of Mali »
Each year, the elephants trek farther on the fringes of the Sahara to find water. They have the longest migration route of any in the continent, traveling "in a counterclockwise circle" of about 700 kilometers (435 miles), Save the Elephants said.
The images are signs of the crisis gripping the northwest African nation.
The U.N. Development Programme ranks Mali near the bottom of its Human Development Index. It cites a 56 percent poverty rate in the country, with nearly a third of the population unlikely to live past age 40, and an illiteracy rate of 77 percent.
The World Food Programme says the majority of infant deaths in Mali are due to malnutrition.
The drought, combined with soaring temperatures, has also led to deaths of cattle, Save the Elephants said. "The stench of rotting corpses fills the air, and what little water remains is putrid and undrinkable by all standards."
In areas where the elephants live and search for water, "the normal peaceful coexistence between the elephants and herdsmen is starting to break down and giving way to conflict over access to water," Wall said.
There is some hope for the weeks and months ahead. "We're hoping the rains start in June, and that will allow the elephants to start drinking out of shallow ponds until the really heavy rains begin" in July or August, Wall said.
But "urgent action" is needed in the interim "to secure water for the elephants," Wall's group said in its news release.
Save the Elephants, which focuses on helping elephant populations worldwide, said it has partnered with a foundation and the Mali government in its fundraising appeal.