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