After years in captivity, the chimpanzees are dependent upon human care. They live on six mangrove outcroppings that make up Chimpanzee Island, situated where the Farmington and Little Bassa rivers meet before emptying into the Atlantic Ocean, about 50 kilometers (31 miles) southeast of Liberia's capital, Monrovia.

The chimps were used in experiments for biomedical research funded by the New York Blood Center, starting in 1975. Some were transported to the islands, and some were born there. The research, which included studies leading to the development of a Hepatitis B vaccine, was stopped after animal rights activists became aware of the island and how the animals were being used.

Originally, 108 chimps were used for the research; the remaining chimps are survivors.

After the studies ended in 2007, according to the BBC report, the Blood Center continued taking care of the animals on a voluntary basis; but that changed in March 2015, when the funding was cut off.

The Humane Society of the United States, based in Washington DC, took over on a temporary basis.

While activists hope to put pressure on the Blood Center to resume funding, there is also a GoFundMe campaign raising money to feed the animals.

It costs $25,000 a month to feed the chimps, who are totally dependent on humans for the diverse diet they require, according to the BBC. Without the food that gets delivered regularly, the chimps would eat leaves only and would eventually die from their restricted diet, according to the BBC.

On its website the New York Blood Center said the animals are owned by Liberia's government, "and their officials have repeatedly acknowledged that they have responsibility for the care of the chimpanzees."

The Blood Center said its support of the chimpanzees was voluntary. "Eventually, we had no choice but to inform the Liberians that we could no longer provide this charitable support and provided advance notice to ensure a smooth transition.”

But the New York Blood Center "walked away from their responsibility," according to Dr. Fatorma Bolay, director of The Liberian Institute for Biomedical Research, which now has custody of the chimps.

Bolay told The Associated Press, "We are doing our best."

The funding pullout created a huge gap of support for the staff and the chimpanzees, said John Abayomi Zeonyuway, a volunteer and co-director of the Liberian institute. The notification also came during the largest ever Ebola outbreak.

"The resources we have now are very limited," he said. "What if the Humane Society pulls out? Then these chimps will starve to death completely."

The Associated Press contributed to this report.