THERE is still a notable sparkle in the eyes of Wicklow sisters Shirley and Denise Delaney as they reminisce on two months spent voluntarily working in an orangutan sanctuary in the middle of the sweltering Borneo Jungle.

Sure, conditions were uncomfortable, biting insects a constant irritation and a simple shower was a luxury you looked forward to dependant on whenever there was any available water. But none of that really mattered once Shirley and Denise found themselves holding a baby orangutan only a few months old, or became so familiar with some of the older orangutans it almost seemed that the great apes looked forward to the daily visit from their Irish caretakers.

The start of their adventure can be traced back to a trip to Borneo a few years ago when the sisters dropped into Sepilok, the world's oldest orangutan rehabilitation centre. The seeds of interest in these noble beasts were then sown.

The Sepilok Orangutan Rehabilitation Centre was set up in 1964 to rehabilitate orphaned baby orangutans. While primate rehabilitation is still the primary goal at Sepilok, it also focuses on public education on conservation, research and assistance on other endangered species such as the rhinoceros.

Having vowed to return, Shirley and Denise went about establishing a number of fundraising initiatives, including an Indonesian night in Ashford in 2007.

Both admit to feeling a strange mixture of nerves and excitement before setting off to Borneo, but neither was prepared for the huge impact Sepilok had on them.

'You spent the whole day holding orangutans and half the time the showers didn't work. You are all day being pulled and tugged at and it's really hot with loads of insects. Usually that would be my worst nightmare but by the end of the two months I didn't want to leave at all,' says Shirley.

Among their duties were to help and feed the orphaned orangutans in Sepilok, transfer them to the jungle and teach them climbing skills, clean and build enclosures and conduct field surveys and nocturnal animal surveys. But nothing prepared them for the pure thrill of working alongside the primates and getting to know their individual personality traits.

Shirley can't help but smile at the memory of two to three of these large and heavy animals clinging on to her as she tried to go about her day-to-day chores.

'Sometimes you had to carry and drag some young orangutans, which still weigh a lot. You would have one on your back weighing 20 kilos and another hanging out of you.'

Their many human like attributes were also evident from day one.

'They play up to the volunteers and study you. They know you are properly a bit softer than the regular rangers. If they know they aren't to do something then they push it to the limit. They are as good as gold when the ranger is around, but as soon as they are gone they go back to being bold again,' adds Denise.

She continues, 'there is a lot of bedevilment. Rough playing, nothing violent. You have to be alert because they will grab you and try and take all the food. You have to be strict with them, just like children really.'

All the volunteers were split into different work rotations so they all had their own different and special experiences while based at Sepilok.

A boardwalk leads to a viewing gallery and feeding platform where members of the public can watch the animals being fed twice a day. Sometimes the orangutans might arrive, other times they don't. It all depends on their mood.

'All the animals are free to come and go and aren't contained in a zoo-like environment,' says Shirley.

'How used they are to people is often obvious by their interaction with humans. While one orangutan will do all it can to stay out of sight, others will happily walk through the crowds gathered at the visitor's platform.'

The busiest rotation was the clinic where you could have anything between three to nine orangutans being looked after, including heavily pregnant mothers to be. Other orangutans looked after in the clinic might have been rescued from situations where they were being held as illegal pets. Because they have been in capacity too long they are often too sick to fend for themselves in the wild.

According to Denise, 'it's very rewarding to watch some of them develop. Some won't make it back to the wild because they have been kept as a pet too long, but at least they now have a great quality of life.'

There was nothing romantic about cleaning out the orangutan enclosures or trekking over the forest floor to conduct field surveys on some of the smaller jungle occupants. But the faces of both sisters light up when the conversation switches to the many baby orangutans cared for in Sepilok.

'Some people actually treat them as human babies,' recalls Shirley.

'One baby came in with pierced ears and everything. You have to rehabilitate them and get them used to the wild.'

Denise recollects her encounter with a female orang-utan who was left partially paralysed after catching malaria in a storm.

'She was so sad and in a deep depression. She was around 12 years of age and we had to get her out mingling with the others. Eventually we got her back out playing with the rest. It was just wonderful to see her brightening up like that. The vet who originally treated her couldn't believe the improvements.'

Denise and Shirley now both want to return to Sepilok and both feel they have some unfinished business to attend to. Certainly heading back home to county Wicklow after their two months had passed proved far more painful an ordeal than either of them could have predicted.

'We didn't want to leave. The people are so lovely and everyone goes to work with a smile on their face. It's such rewarding work that I am just counting down the time until I head back again,' says a determined sounding Denise.

As a parting gift they bought some new cages for the orangutans and a new stove for the kitchen.

Shirley can still remember the reaction they received from the Sepilok personnel.

'They were so happy you would have thought we had just spent €1 million on them. The whole experience was just fantastic.'