First they ate leaves. Then they ate roots, soaked for five days and boiled until they were just edible. Now many have eaten the planting seed _ and their future with it.
There is no food left in the Nuba Mountains, so the stream of tens of thousands of hungry refugees pouring across the militarized Sudan-South Sudan border has almost doubled in the past two months.
The Yida camp now holds 31,000 refugees and is bracing for thousands more, as desperate families rush to make the five-day trek south from Sudan on foot before seasonal rains arrive, turning the rough dirt road muddy and impassable, and choking off food deliveries for months.
Back in their homeland, the refugees have endured bombardment from Sudanese warplanes and a crisis-level food shortage they blame on Sudan's president. Aid groups say Sudan _ a mostly Arab nation _ is intentionally trying to starve the black residents of the Nuba Mountains.
Refugees report the deaths of young and old back home.
"There's no food where we live. People are eating the leaves of trees, said Amira Tia, who arrived at the camp last week after walking in green flip flops for four days with her four children.
"Every morning they go to the bush to collect leaves. There is also a root of a tree that if you soak it for five days and then boil it, it is edible," she said.
Sudan does not allow aid from U.N. or international groups to be delivered to Nuba, and no official assessments have been done about the conditions there.
Geoffrey Pinnock, the World Food Program's emergency officer in Yida, fears that unknown.
"What we hear from refugees is that things are bad and getting worse," he said. "Some people haven't had solid food in two months and then walk five days" to reach the camp.
Muniara Kamal walked for six days, carrying her 9-month-old daughter, Safa, who wore a red sweatshirt with white hearts and swatted feebly at flies while getting medical care. Tia said the group she was walking with was attacked by Sudanese Antonov bombers twice. One man was cut in half by shrapnel, she said.
When South Sudan voted to break away from Sudan last year after decades of war, the people of the Nuba Mountains were caught in the middle. They are black, like those of the south, not Arabs like the northerners of Sudan. Now a full-on war is under way in their homeland.
Even once they reach the relative safety of the camp, the threat of war remains. South Sudan's military is on alert in case border skirmishes with Sudan escalate into a full-scale conflict.
The Yida camp is far more militarized than aid workers would like. South Sudan troops move through, as do northern rebel groups fighting Sudan. U.N. and other aid workers quietly say the rebel fighters use the camp for food and rest. International aid groups have dug deep foxholes in their compounds in case Sudan bombs again.
New arrivals must walk within 20 yards (meters) of an unexploded bomb dropped by a Sudanese aircraft in November that landed on the road leading to the camp from the north.
The rate of new arrivals has risen rapidly in recent days. Aid workers and Nuba leaders say 15,000 or even 30,000 more Nuba could reach Yida in coming weeks.
With the rains expected to start around June, WFP is rushing to deliver 5,000 metric tons of food. On a recent day, dozens of Nuba men erected large storage facilities and unloaded sacks of food from the U.S. government's aid arm, USAID.
The camp has a dirt airstrip, but the rains threaten to make it unusable. Goods could be parachuted in or dropped by helicopter, but both methods are extremely expensive for a large refugee population.
Ibrahim Kallo, the head of the International Rescue Committee in Yida, said he's not counting on the runway being usable after the rains set in. A recent emergency evacuation of a pregnant woman underscores the danger of being isolated by rain.
The group sent the woman to Bentiu, the nearest city, a three to four hour journey by truck over a jarringly bumpy dirt road even when it's dry. The mother made it to the hospital just before some early rains arrived. But on the way back to the camp the truck got stuck, and the mother and her 3-day-old newborn had to spend the night in the truck without food, Kallo said.
At Yida, straw huts covered by blue or white UNICEF tarps sit among trees and towering termite mounds spiraling 12 feet high or more.
The stick-thin children wear torn or dusty clothes. Most are barefoot. The women vastly outnumber the men, many of whom stayed behind to fight the Sudanese Armed Forces.
The U.N. calls Yida a transit camp and wants the residents to move to two camps farther south, but most refugees prefer to be closer to home _ and to the tree cover in Yida that provides protection from the merciless sun.
Aid workers say the proud Nuba don't like to take handouts. Conor Lucas-Roberts, the 29-year-old head of Samaritan's Purse, the largest aid group here, noted that the refugees build their own homes. People are even starting their own churches and businesses, setting up small shops and a "movie theater" _ a tent with a few chairs and a TV.
Hussein Algumbulla, the chief representative for the camp's residents, said the Nuba hate asking for help. "We need only scythes and next year we can say to WFP, you can come buy food from us," he said.
Algumbulla says he expects the camp's population to swell to more than 60,000 people in coming months, a number the U.N. refugee agency is also bracing for, according to Peter Trotter, the head UNHCR official at Yida, noting that conditions in the Nuba Mountains will only get worse.
"They should be preparing land now but are not. There are reports of people eating their seed stock, so they have nothing to plant," he said.
Amjuma Ali Kuku, a 24-year-old teacher, cares for the camp's unaccompanied children. At first the job was manageable, but there are now 2,000 children without parents.
"For some of them, when the war broke out, they ran with the teachers and that is why they are here," she said as dozens of girls played with a tattered ball nearby. "Some of them don't know if their mothers or fathers are alive."
Of the hundreds of children Kuku oversees, only 16 have been reunited with their parents. Kuku's compound of teenage and young girls has no security, and food has disappeared, leaving the girls hungry. The WFP is trying to improve security.
But Kamal feels safer in Yida than in Nuba, which she hopes can somehow be annexed by the south, something Sudan President Omar al-Bashir is not likely to allow anytime soon. She plans to stay away until there is peace.
That may take a long time.