The Diverse Orangutan

Serge Wich

Ketambe

Ketambe

Logging (1999-2002)

Forests cover reduction on Sumatra

This is 11 years ago!

(UNEP 2007)

Forest cover reduction on Borneo

Reduction in orangutan distribution

(UNEP 2007)

One orangutan species: two subspecies?

Morphology & genetics

• Morphology (Groves 2001, Taylor 2006)

• Mitochrondial DNA (Warren et al. 2001)

• Pongo abelii (Sumatran species)

• Pongo pygmaeus (Bornean species)

- P. p. pygmaeus

- P. p. wurmbii

- P. p. morio

Two species (one on Sumatra and one on

Borneo; three subspecies on Borneo)

Where do the two species live and how

many are there?

Nest transects

How to determine where to look for orangutans?

Survey work

Areas surveyed or with reliable reports

(Wich et al. 2003, Wich et al. in prep)

Sumatra Pongo abelii: 6,700 (Critically endangered)

Borneo

P. pygmaeus pygmaeus

3,700

P. p. morio

16,000

P. p. wurmbii

35,000

P. pygmaeus: 55,000 (endangered)

0

50000

100000

150000

200000

250000

1900

2003

What has been the decline for orangutans?

Orangutans on Borneo

Orangutans on Sumatra

Borneo Sumatra

Pongo abelii

P. pygmaeus

pygmaeus

P. p. morio

P. p. wurmbii

Based on genetic and morphological differences

(Warren et al. 2001, Groves 2001)

Orangutan density on Sumatra and Borneo

(Marshall et al. in prep)

red = Sumatra

blue = Borneo

Soil Fertility (i.e. productivity) Sumatra > Borneo?

Measuring fruit availability

Fruit availability: Borneo & Sumatra

(Fredriksson et al. 2006)

0

5

10

15

20

25

30

Jan-

98

May

-98

Sep

-98

Jan-

99

May

-99

Sep

-99

Jan-

00

May

-00

Sep

-00

Jan-

01

May

-01

Sep

-01

Months

% t

rees f

ruit

ing

Sumatra

Borneo

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

Ad

ult

ora

ng

uta

n p

art

y

siz

e

(sub)species

P. p. morio

P. p. wurmbii

P. abelii

Female sociality

(Delgado and van Schaik 2000) (no data for: Pongo pygmaeus pygmaeus

N = 2 sites for each spp

Larger parties on Sumatra than Borneo

Male-female consortships: longer on Sumatra

Orangutan diet

Sample of the orangutan diet

Nuts Leaves Skin around seed

Figs Flowers Bark

Sample of the orangutan diet

Ants from nest Marrow from a twig

Fruit is high in caloric value

Item Kcal/gram

Non-fig fruit 335

Leaves & figs 176

Bark 177

(Knott 1998)

Bark eating

Bark eating: scrape of the inner layers

% bark in diet for Borneo and Sumatra

0

10

20

30

40

50

60%

in

die

t

mean

min

max

(Wich et al. 2006)

N=2 sites each spp

Fruit availability: Borneo & Sumatra

(Knott 1998, Wich et al. 2006, Fredriksson et al. 2006)

0

5

10

15

20

25

30

Jan-

98

May

-98

Sep

-98

Jan-

99

May

-99

Sep

-99

Jan-

00

May

-00

Sep

-00

Jan-

01

May

-01

Sep

-01

Months

% t

rees f

ruit

ing

Sumatra

Borneo

Inner bark

Item Kcal/100gram

Non-fig fruit 335

Leaves and figs 176

Bark 177 (Knott 1998)

2.5 hours feeding

High

Fruit availability

Low

Orangutan Reproduction: Gunung

Palung (Borneo)

(Knott 1998, 2001)

Energy balance +, Estrogen↑, Matings↑, Conceptions↑

Energy balance - , Estrogen↓, Matings↓, Conceptions↓

(Knott 1998, 2001)

Energy balance measured with ketones (metabolite of burning body fat)

How to measure energy budget: Urine strips

Sumatran orangutan urine collection

No ketones found in urine of Ketambe orangutans

(N=234 samples, 3 flanged,

3 unflanged, and 7 females)

Thus energy balance

not negative for long periods

(Wich et al. 2006)

Sampled evenly over high and low

fruit productivity periods

High

Fruit availability

Low

Orangutan Reproduction: Ketambe

(Sumatra)

(Wich et al. 2006)

Energy balance +, Estrogen↑, Matings↑, Conceptions↑

Energy balance - , Estrogen↓, Matings↓, Conceptions↓

Effects on morphology as a result of bark feeding?

Orangutans on Borneo have more robust jaws

Cheekbone

Sumatra Borneo (Taylor 2006)

Are there developmental differences?

Interval between births

5

6

7

8

9

10Y

ears

mean

min

max

(Wich et al. 2004)

Weaning age

(van Noordwijk et al. in review)

Sumatra: 6-7.5 years

Borneo: 5-6 years

Borneo Sumatra

But why do we find these differences?

• High extrinsic mortality - predation

- disease

- starvation

Leads to faster life history to be able to

reproduce before dying

(Williams 1957, Charnov 1991, 1993, Stearns 2000)

Bark feeding and mortality risk

Fruit availability (Sumatra > Borneo) variation

is related to island differences in:

• Density (Sumatra > Borneo)

• Sociality (Sumatra > Borneo)

• Diet (less bark feeding in Sumatra than Borneo)

• Reproduction (Sumatra always, Borneo not in scarce periods)

• Interbirth intervals (Sumatra > Borneo)

• Development (Sumatra > Borneo)

• Jaw morphology (Sumatra less robust than Borneo)

• Density & Sociality

• Diet

• Reproduction

• Interbirth intervals

• Development

• Jaw and brain morphology

• Behavioral repertoires

Genes Ecology Social Learning

1) between species (mother-infant call)

Orangutan diversity:

Orangutan diversity:

2) between subspecies (nest smacks)

Orangutan diversity:

3) within (sub) species (Neesia tool use)

Orangutan diversity:

4) between individuals of

the same population

Thus conservation needs to focus on more than the

species and subspecies to preserve this diversity

P. p. morio

Borneo

P. p. wurmbii

Borneo

P. abelii

Sumatra

Conservation should aim to conserve

orangutans at the population level at least

Sumatra: signs of hope?

Batang Toru

Orangutan diversity in zoos?

Thanks to:

Suci Utami, Tatang Mitra Setia, Herman Rijksen, Chris Schürmann,

Carel van Schaik, Jan van Hooff, Tine Geurts, Ralph Buij, Andy Marshall,

Mark Leighton, Ian Singleton, Gabriella Fredriksson, Andrea Taylor,

Cheryl Knott, Anne Russon, Erik Meijaard, Rona Dennis, Rob Shumaker,

Tim Laman, Perry van Duijnhoven Ellen Meulman, NHK, TVNZ, all

students and field assistants and many others.

&

NWO, WOTRO, Leakey Foundation, Dobberke Foundation, Lucy

Burgers Foundation, Van Tienhoven Foundation, Pan Eco, SOCP, LMU,

Fauna and Flora International

Thank you for your attention!

P. van Duijnhoven