He said the humane society has been paying for food and repairs since March 6, when funding from the blood center stopped, but that caretakers are working for free.

“Why would they walk away from the animals?” Dr. Bolay said about the blood center’s funding withdrawal. “We have to find a solution to take care of these animals.”

The history of the research center, called Vilab II, dates back to 1974, when the blood center contracted with the institute to do research primarily on the hepatitis virus, which survives in blood and posed a threat to the safety of the supply of donated blood. Around this time, the United States banned importation of chimpanzees caught in the wild.

By 2005, the blood center had stopped research on the chimps and started trying to make arrangements for their long-term care. A 2014 Vice documentary, Island of the Apes, chronicled the history of the lab and the islands on which the chimps now live.

A decade ago, the blood center appeared to be committed to caring for the chimps in retirement. Alfred M. Prince, director of the Vilab II project for the blood center, wrote an article in the American Society of Primatologists Bulletin in December 2005, seeking a foundation to take over care of the chimps. Dr. Prince wrote that the blood center “recognizes its responsibility to provide an endowment to fund the Sanctuary for the lifetime care of the chimpanzees.”

But Ms. O’Neill said in an email that this was Dr. Prince’s opinion and was “not authorized or approved” by the blood center. She added that the center “did not ever establish any endowment for animal care, chimpanzees included.”

In 2007, the blood center withdrew its staff from the institute in Liberia, but continued to support the chimpanzees. In January, Dr. Bolay said the blood center informed the institute that March 5 would be the last day of support. Previous negotiations about the chimps’ future had broken down, Dr. Bolay said.