Gerald Herbert / AP An adult chimp plays with a young chimp at Chimp Haven in Keithville, La., Monday, Feb. 18, 2013. One hundred and eleven chimpanzees will be coming from a south Louisiana laboratory to Chimp Haven, the national sanctuary for chimpanzees retired from federal research.

For the first time in their lives, four aging chimpanzees once used in federal research can go outside whenever they like. They can lie on the grass, clamber onto a platform 20 feet up on a chimp-style jungle gym and gaze freely at the open sky, the vista unbroken by steel bars.

Julius and Sandy, both 52, Phyllis, 46, and 44-year-old Jessica have arrived. They and several other primates are now "living like chimpanzees" as they play, groom each other and tussle at Chimp Haven in northwest Louisiana — the only national sanctuary for retired federal research chimps.

Julius' group is among 111 chimpanzees coming to Chimp Haven over the next 18 months from the University of Louisiana at Lafayette's New Iberia Research Center. They could be the vanguard of a much larger immigration of former research chimps on the way to the refuge in Keithville, La.

A National Institutes of Health committee recommended Jan. 22 that most of the other 350 federally owned research chimpanzees be retired to "the federal sanctuary system" — a system of one. The agency's director will decide whether to accept the recommendations after a 60-day period for public comment.

The proposal to retire all but about 50 federally owned chimpanzees is the latest step in a gradual shift away from using chimps as test subjects, owing to technological advances and growing ethical concerns about research on primates that share more than 98 percent of the DNA of humans.

Research on the chimps has ranged from psychological studies to development of vaccines for HIV and hepatitis.

The arrivals are staggered so the small staff can integrate small groups of newcomers with old-timers at Chimp Haven. And some of the living quarters and play spaces haven't yet been built at Chimp Haven, which opened in 2005.

The newcomers led by Julius were among nine that arrived Jan. 22. Another seven arrived later that week and eight more Tuesday.

They got their first view of unobstructed sky last week. New arrivals spend 17 days in quarantine before being moved into an indoor bedroom area near a bedroom occupied by chimps already settled into the sanctuary, to see how they get along.

Their first outdoor time is in one of two grassy, quarter-acre play yards that open onto the bedrooms. A network of steel mesh tunnels lets the staff move chimps from any part of the sanctuary to any other.

Staffers say it's amazing to see them savor new freedoms.

"They light up, look up at the sky, look at us watching them," behaviorist Amy Fultz said.

Like most newcomers to Chimp Haven, Julius' group first explored the edges of its new surroundings. Their play yards are surrounded by a high concrete wall that can't be climbed, and the larger areas of dense pine forest by similar concrete walls and, on one side, a moat.

Chimps in the wild make regular perimeter patrols, alert for any encroaching bands and for a chance to expand their own territory.

These retirees will send the rest of their lives at the 200-acre sanctuary in a forested park belonging to the Caddo Parish government, which donated the land to Chimp Haven. www.chimphaven.org

They get about a month at a time with access to each of the quarter-acre play areas and the habitats of 3 to 5 acres populated by dense stands of pines where the primates can nest high in the trees.

Two other groups of recent arrivals from the university lab in New Iberia are getting acquainted with each other because each includes a youngster. The aim is to meld them and other groups with juveniles into a group with Chimp Haven's three "oops" babies, all sired by Conan, who has been at Chimp Haven for years.

The 111 incoming chimps include a total of eight youngsters; one was born to a female chimp with HIV, but the others and their mothers all are destined to become part of Conan's social group.

On Tuesday, Conan's crowd was in a play area, catching fruit thrown by staffers. A female named Sheila slapped her hands together and then held up an arm to attract attention.

A few minutes' walk away, another group of 15 chimps raced from the steel mesh tunnel between their sleeping area and a 5-acre forested habitat toward an array of fruits and vegetables strewn on the ground. Some grabbed a hoard of bananas, apples and oranges before starting to munch; others ate immediately.

After a bit, several turned to a tall, pointed structure with PVC pipes stuck in it — an imitation termite mound. In the wild, chimps poke sticks into termite mounds to pull out insects to eat. At Chimp Haven, the tubes may hold honey-coated bits of fruit or sugar-free candy, inducing the great apes to use tools as they would in the wild.

Fultz said some newcomers won't even step on the grass in the play yards, but Julius' group had no qualms.

"They sit and look around. They look up at the sky. To me, they seem to be thinking, 'There's no bars,'" Fultz said.

That isn't to say bars don't exist in the sanctuary.

Indoor bedrooms, furnished with straw and blankets for making nests, and old fire hose for climbing, have steel mesh interior walls to keep chimps in.

Chimps with HIV, hepatitis or other major medical or psychological problems have outdoor areas surrounded by the same wide, heavy steel mesh. The peaked ceilings are of pipes laid a few inches apart from each other so the chimps can swing across the ceiling arm over arm, as they might in trees.

"Those spaces are huge. They're huge," said Lori Gruen, a Wesleyan University philosophy professor who specializes in animal ethics and has websites devoted to the issue. Chimp Haven is "a pretty remarkable facility. I think it will be quite interesting and exciting to see it expand."

But there's a major hurdle. When Chimp Haven was made the national sanctuary in 2002, Congress capped spending on the project at $30 million. That cap will be hit this year.

U.S. Rep. John Fleming, a Republican representing northwest Louisiana, said in a statement emailed by his press secretary that any additional federal spending "will be difficult" in the current budget climate of mounting federal debt and ongoing national security priorities.

Kathleen Conlee, vice president for animal research issues of the Humane Society of the United States, and other advocates say there's no need for additional spending if Congress would let NIH put money now spent on research contracts into the animals' retirement.

That would save money, because the 75 percent federal share of care at Chimp Haven is lower than the research contracts' cost, Conlee has said.

With help from the Humane Society and other nonprofit groups, the sanctuary has in recent months raised $2.6 million needed to add bedrooms, six play yards and an open-air enclosure to accommodate all 111 federal chimps coming from New Iberia and another $100,000 toward a total $5.1 million goal announced in November.

"We certainly expect and hope the cap will be extended," said Cathy Willis Spraetz, who became president of Chimp Haven three weeks ago.

If it isn't? "Then we have to rely on our wonderful donors," she said.