Our Accidental

Success Story

The dynamics of a multi-male Sumatran

orangutan group

Kim Emerson

Saint Louis Zoo

Zoo and SSP goal

• One of our goals has

been for our adult

female to conceive

and rear another

offspring.

• Attempts made since

2010 with no success

Group Composition

• Merah – adult female – 44 years – breeding

female

• Rubih – sub-adult female – Merah’s daughter – 9

years

Male #1: Robert B • Robert B arrived in 2011 based on

recommendations by the SSP.

• Previous institution had recorded

copulation with their female

• Introductions uneventful

• Robert showed no sexual interest

in Merah

• Two years later and still no

interest

Moving Forward

• Robert B great social

addition

• Merah and Rubih

enjoyed spending time

with him

• Lack of copluation

• Conflicted on how to

move forward

• Due to Merah’s age and

valuable genetics

something had to be

done.

How?

• Due to several factors, Robert could not

immediately be placed at another institution.

• Multiple questions arose:

• Give up on the breeding for Merah?

• Bring in another male and house two

males separately?

• If we brought in another male more

questions arose:

• Housing capabilities?

• Male suppression?

• Aggression?

• Tolerance?

Male #2: Cinta

• We inquired with the SSP

and there was a younger

male that needed to be

placed.

• Cinta – un-flanged male – 9

years

Plan #1 • Introduce Merah,

Rubih and Cinta

together

• Robert would

remain out of the

group during

introductions

• SSP possibly find a

new home for

Robert in 2-3 years

Introductions

• Introductions proven to be quite difficult

• Merah constantly aggressed Cinta

• Ended introductions after aggression did

not dissipate

• Re-grouped and came up with alternate

introduction plans

• Consulted with SSP

Plan #2

• SSP recommendation

• Rubih and Cinta introduced without Merah

• Merah happy with this arrangement

• Rubih and Cinta stayed away from each other

• No interactions seen

• Ended this after a few days when Rubih began

exhibiting severe stress behaviors

Rubih’s injury

• Self-mutilating behavior

• Rubbing front teeth/gum

line against steel cage mesh

• Large hole exposing jawbone

• Occurred during one overnight

• Two anesthesia’s resulting in front tooth

extraction

• Loss of trust with Rubih

Time Out

• Decided to time out the

introductions

• Boys separated

• Gain more trust with

Cinta

• Merah and Rubih together

• Allow Rubih time to heal

• Gain Rubih’s trust back

Moving Forward (Again)

• Gained trust back with Rubih

• Decided to try Merah, Rubih

and Cinta again

• Still didn’t work

• Constant aggression

• Attempted for another

several days with the same

result

Mixed Emotions

• Frustration – no progress in any direction

• Confusion – why was Merah acting this way

• Disappointment – no copluation = no baby

• Sadness – Robert temporarily living alone

• Due to off exhibit housing constraints we

had to move Cinta into a holding cage with

mesh access to Robert.

• Keepers standing by to observe behavior

and potential aggression

Surprise!

• But we didn’t see ANY

aggression.

• Quite the opposite.

• It was the most

positive interaction we

had seen between

Cinta and another

orangutan since his

arrival in Saint Louis.

Instant Friends

• Robert did not seem to mind the new guy.

• Cinta immediately drawn to Robert.

• Ran over to sit near him.

• Held his hand.

• Robert did not move away.

• Food sharing between the mesh.

• Nesting near each other overnight.

Plan #3???

• Keepers began

brainstorming ideas to

have Robert help us get

Cinta into the group.

• Merah, Rubih and

Robert have an excellent

relationship.

• Robert= glue?

• Male to male

introductions?

Plan #3 = Two Males

• We decided to move forward by introducing

the two males.

• Gave them as much room as possible for the

introductions which included off exhibit and

the indoor dayroom.

Male Intros • Completely uneventful

• Cinta glued to Robert’s side

• Robert did not mind

• Nesting, feeding, sitting near

each other most of the day

• Separated at night with mesh

access to continue facilitating

positive interactions

Two Dyads • Continued like this for over a month

• Allowed males time to bond

• Alternated groups on and off exhibit

Re-Introduced

• Time to move forward

• Introduced 2 males to 2

females

• Merah initially aggressed

Cinta

• Robert watching

• Occasionally intervening

• Rubih sticking close to

Merah or stayed away from

everyone

• Cinta stayed with Robert and Merah and Rubih

stayed with each other

• Merah aggressed upon initial release into exhibit

• Time spent aggressing decreased over time

• Rubih more curious about Cinta and vice versa

Cinta + Rubih

• Increased proximity

• Increased curiosity

• Pestering

• Testing boundaries

• Eventually led to no boundaries

• Play!

Cinta + Rubih ≠ Merah

• Decreased aggression

• But still no interest from

Merah

• Cinta curious but

nervous

• Interactions daily with

most orangutans

• The exception =

Merah and Cinta

Interesting

• Increased

grooming among

all orangutans

• Cinta groomed

Robert daily

• Merah’s grooming

of Rubih also

increased

• Rubih groomed

Robert

occasionally

Happy?

• Content with this situation

• Social companionship for all

Living together, now what?

• Increase neutral interactions between Merah

and Cinta

• Merah still spent more time with Robert when

ovulation was predicted

• Perhaps due to Cinta’s age/size she did not

consider him for breeding.

• Especially with an adult male like Robert

around

But…

• Merah and Cinta began sitting in close

proximity when others were also present

• No aggression during these encounters

• Contact made!

• Hand touching

• Eating in proximity

• 4 orangutans nesting near each other

Spring/Summer 2013

• Back into outdoor

habitat

• Merah protective of

outdoor habitat

• Aggression returned

but short lived

Late summer 2013

• Age still a factor for Merah

• Still want breeding

• New plan hatched

• Continued social

companionship for

Robert

• Continue breeding

attempts with

Cinta/Merah

• Keep Merah/Rubih/Cinta together 24/7

• Given access to holding and exhibit

• Separate Robert out for 8 days

• During Merah’s predicted ovulation range

• One month completed

• First few days everyone seemed confused and

concerned about Robert’s whereabouts

• Adjusted well after that

Right Direction

• Increased sexual

interest

• Zero previous

interest

• Happy with this

progress

• Will continue with the

temporary separation

for the time being

Final Thoughts

• Orangutan group = not the norm

• Goals achieved

• Social companionship for all orangutans

• No aggression from Merah

• Goals in progress

• Sexual interest between Cinta and Merah

• Increase Cinta’s confidence