But the colony of 66 chimps has been at the centre of an international storm since the New York-based blood bank funding it announced in March it was stopping the cash.
The New York Blood Center (NYBC), which carried out about 30 years of biomedical research on the animals, had publicly committed to their lifelong care after they were retired in 2005.
The Humane Society of the United States (HSUS) is supporting the colony through emergency fundraising as the Liberian government and the blood bank lock horns over who should be responsible for their care.
"NYBC may believe that people will forget and that this will go away, but I can assure you that it won't," HSUS vice-president Kathleen Conlee told AFP in an email from Washington DC.
"They are absolutely responsible for the long-term care of these chimpanzees."
Conlee described the chimps' care costs -- estimated at $30,000 (27,000 euros) a month -- as "a mere drop in the bucket for this organisation that has hundreds of millions in revenue annually".
- 'Moral obligation' -
The Liberia Biomedical Research Institute (LBRI) entered into an agreement with the NYBC in 1974 to carry out research in a lab about 65 kilometres (40 miles) southeast of Monrovia, capturing or buying the chimpanzees.
The research project had gained a world class reputation in the field of viral infections, particularly hepatitis, by the time it ended and the NYBC appeared to make a commitment to the chimps in retirement as a reward for their contribution.
NYBC director Alfred Prince wrote in the American Society of Primatologists Bulletin in 2005 that Monkey Island was to become "a dedicated full-time sanctuary".
"NYBC recognises its responsibility to provide an endowment to fund the sanctuary for the lifetime care of the chimpanzees," he wrote.
The chimps are entirely reliant on humans for their survival, as there is no year-round fresh water supply or enough food on their islets.
LBRI head Fatorma Bolay said initial emergency funding from the HSUS, pooled with cash from other sources, had probably saved the animals from dehydration and starvation.
World-renowned chimpanzee expert Jane Goodall sent an open letter to the NYBC in May urging the organisation to consider its "moral obligation" to continue funding the chimps' care.
"I find it completely shocking and unacceptable that NYBC would abandon these chimpanzees and discontinue support for even their basic needs," she wrote.
AFP emailed and telephoned the NYBC but the centre did not respond to requests for comment.
- 'No different from humans' -
John Abayomi Zeonyuway, a volunteer at the institute, showed AFP the animals' care routine on a recent visit to Monkey Island, a 25-minute speedboat ride up the John River from Roberts International Airport.
As the boat approached the first of the islets, a nine square-kilometre patch of jungle known as Island Five, a welcoming party of four chimps began screeching and jumping up and down excitedly.
"This is their way of saying that the food is here," Zeonyuway explained as he threw pawpaws, bananas and other fruit for the animals.
Zeonyuway visits the colony every second day, and each time he does a mental roll call to ensure all are present and in good health.
"I can't see Samanta. Bullet is here -- he's already eating," he called out to his crew as the rest of the residents came to join the feast.
The boat then proceeded to Island Four, 15 minutes away, where the clan of ten apes included four unplanned babies, the result of failed vasectomies, according to the HSUS.
Birth control efforts have since been stepped up so that the population doesn't grow further.
At all six of the islands the routine was the same: an excited greeting and a feast for the animals.
"The chimps are part of me. I am glued to them because I see them every other day," Zeonyuway told AFP.
"They are no different from humans. They fight and they make peace. They need help, they need attention. We cannot afford to lose these animals to hunger and sickness."