Bhubaneswar: There is no mother orangutan in the quarantine enclosure at Odisha's Nandankanan Zoological Park.

Instead, there is music.

Soft instrumental notes fill the space where five infant orangutans would ordinarily hear the sounds of the forest – leaves moving above them, branches shifting, distant rain and, most importantly, the reassuring presence of their mother.

For these five babies, the zoo's challenge is therefore much bigger than treating illness.

It is about recreating, as far as possible, a sense of security after an extraordinarily traumatic separation.

The caretakers have turned to carefully controlled classical music, combining it with touch, warmth, sunlight, food and companionship in an attempt to calm the infants while veterinarians monitor their medical condition.

The objective is not to entertain them.

It is to reduce distress and help their nervous systems settle.

And behind that intervention lies a much larger question – one that could become central to the international investigation into how the five orangutans reached Odisha:

Where, and at what point, did these babies lose their mothers?

When silence itself can become stressful

For an infant orangutan, the absence of its mother is not a small behavioural disruption.

The mother normally provides protection, warmth, transportation, feeding and behavioural learning. Physical contact is a fundamental part of an infant's early development.

That makes the behaviour now being observed at Nandankanan particularly significant.

The babies have been seen clinging to one another, vocalising, self-hugging and retreating together.

Their instinct appears to be to seek security from whatever source is available.

And that is where the zoo's unusual auditory intervention comes in.

Rather than continuously filling the quarantine enclosure with music, veterinarians and primatologists will be using short, controlled sessions.

Nandankannan Tunes in Whispers of Rainforest, Missing Mother's Heartbeat

As per experts, the music is typically played for around 3 to 4 hours a day, divided into blocks of approximately 30 to 45 minutes.

The timing is deliberate.

Sessions can be used around periods that may increase anxiety – after feeding, during veterinary procedures and around sunset, when infant primates naturally become more restless and seek their mothers before sleeping.

Then comes silence.

The music is switched off completely between sessions.

The reasoning is simple: what begins as soothing stimulation can eventually become another source of sensory stress if it is played continuously.

The infants therefore get periods in which they can hear the ordinary sounds of their surroundings without an artificial auditory layer.

The music is designed to sound less like music, and more like safety.

What the zoo broadly describes as classical music is being shaped around a particular acoustic idea.

The intention is to avoid anything sudden, loud or startling.

The selected soundscape relies on slow, steady rhythms and soft instrumental tones.

Music around 50–60 beats per minute is used as a calming reference because it resembles the slow rhythm associated with a resting heartbeat of their missing mother.

The emphasis is on instruments such as harp, cello and flute, together with gentle piano.

For an animal whose natural environment is a rainforest, abrupt booming sounds can potentially resemble something very different from comfort – a falling branch, sudden disturbance or approaching threat.

The aim, therefore, is to create an auditory environment that does not demand attention.

It simply surrounds the babies.

Alongside the instrumental music, nature-infused sounds such as rainfall, rustling leaves and distant streams can form part of the broader sensory environment.

It is an attempt to replace some of the artificial noises of a zoo setting – human voices, doors, machinery or vehicle sounds – with a softer auditory background.

In effect, the keepers are trying to build an "auditory blanket of safety."

Why music may matter to a traumatised great ape: The Science

The logic behind the intervention goes deeper than simply "calming music".

Stress activates the body's emergency response.

In a frightened infant, the amygdala can trigger the hypothalamic-pituitary-adrenal (HPA) axis, resulting in the release of stress hormones including cortisol.

When that response remains elevated, the animal can stay locked in a state of heightened alertness.

The proposed purpose of slow, predictable auditory stimulation is to help shift the nervous system away from that constant state of alarm.

As the stress response comes down, physiological indicators such as heart rate and other signs of agitation can also become easier to regulate.

For highly intelligent great apes, predictable sensory stimulation may therefore serve as one component of a broader behavioural and veterinary strategy.

But the music is only one piece of the puzzle.

The real therapy is multi-sensory

The quarantine programme being followed at Nandankanan goes well beyond sound.

Specialists, including members of the Wildlife Institute of India, have been involved in a broader enrichment strategy.

The principle is important: an infant orangutan does not experience security through sound alone.

It experiences the world through touch, movement, warmth, food and social contact.

So the intervention attempts to address each of these needs.

Teddy bears become surrogate comfort objects

Large plush teddy bears have been provided to the infants.

The reason is strikingly simple.

The babies have lost the physical contact that would ordinarily come from their mothers.

The soft toys give them something to hold, hug and cling to.

They can provide a physical object against which the infants can curl themselves when they are seeking comfort.

It cannot replace a mother.

But in a stressful quarantine environment, it can provide tactile stimulation and a familiar physical anchor.

Swings and slings recreate the movement of the forest

Orangutans are arboreal animals.

Movement through a forest canopy is part of their natural behavioural world.

That is why the quarantine environment has also been equipped with hanging fabric slings, swings, hammocks and ropes.

The structures allow the infants to grip, climb, swing and hang.

The movement is important not only as enrichment but also because it gives them opportunities to express behaviours associated with their natural motor development.

A stationary quarantine enclosure can never reproduce a rainforest.

But it can be made less alien.

Morning sunlight becomes part of treatment

Every morning, the infants are taken from the quarantine cells into a secured area for sunbathing.

Natural light serves another function.

It helps establish the body's daily rhythm and gives the animals exposure to sunlight in a controlled environment.

For animals already facing the disruption of relocation, quarantine and maternal loss, maintaining a predictable daily routine becomes another part of stabilisation.

The day therefore begins not with confinement alone, but with light, movement and controlled exposure to the outside environment.
Feeding every two hours

The infants are also being managed much like nursery patients.

Their diet includes human infant milk formula, boiled mashed apples and bananas, with feeding taking place every two hours.

The feeding routine does more than provide nutrition.

For an infant under extreme stress, predictable feeding can also provide structure.

Food arrives at regular intervals.

Caregivers arrive at regular intervals.

The environment follows a routine.

That predictability can become important when virtually everything else in the animals' lives has changed.
The Key Takeaway

And perhaps the central idea behind the entire intervention is: the zoo is not trying to make these infants forget the rainforest. It is trying to make the unfamiliar world feel safe enough for them to survive it.

Until the medical crisis passes.

Until the investigation establishes where they came from.

Until their exact subspecies is identified through genetic sampling.

And, ultimately, until authorities determine whether their future lies in long-term placement or possible repatriation to Indonesia or Malaysia, depending on what the international investigation establishes.
Also Read: Special Report|Five Days on Smuggler Route, Heavily Sedated: The Alarming Body Signals Triggering Medical Crisis for Nandankanan’s Baby Orangutans