ELECTRONIC SUPPLEMENTARY MATERIAL
PRIMATES
Seed predation by bonobos (Pan paniscus) at Kokolopori,
Democratic Republic of the Congo
Georgiev, A.V., Emery Thompson, M., Lokasola, A.L. & Wrangham, R.W.
METHODS: SUPPLEMENTARY INFORMATION
Data Collection
Party composition & feeding locations
For assessing party membership, we defined all individuals travelling within 50 m of each
other or arriving at the same feeding location within 15 min of each other as members of the
same party. We defined feeding locations in the following manner. An arboreal feeding
location was a single tree; two or more trees with adjacent crowns allowing continuous
feeding; or a grove of trees each of which was within 50 m of each other and in which
bonobos were feeding concurrently. A terrestrial feeding location was the area under a tree
crown; under adjacent crowns; or under the crowns of trees within the same grove (for items
such as seeds that fell from trees); or as a patch of herbs separated by less than 50 meters
from neighbouring patches.
Urine Sampling and Analysis
We collected urine samples at dawn when bonobos urinated from their nests. We sampled
from midstream using a 1-2 m long stick with an attached disposable plastic bag at the end
whenever possible, and when not, we pipetted urine off vegetation if it was certain that only
one individual urinated in that place. Collecting chimpanzee urine from the forest foliage in
1
this manner does not affect results of hormonal analyses (Muller and Wrangham 2004). We
stored urine samples on filter paper within 24 hrs of collection (usually within 12 hrs),
following the protocol described by Knott (1997). We kept urine samples in airtight
containers with silica gel for up to 3 months in the field, and then in a freezer (-20°C) at the
Primate Reproductive Ecology Laboratory at Harvard University. A.V.G. and M.E.T. carried
out the subsequent hormonal analysis at the same facility, with each set of samples assayed
approximately 6 months after collection. We assayed urinary C-peptide with commerciallyavailable radioimmunoassay kits (DSL Labs, Webster, TX) following previously-described
protocols (Sherry and Ellison 2007; Emery Thompson and Knott 2008; Emery Thompson et
al. 2009). Intra-assay coefficients of variation (CV) for replicated filter paper samples were
11.8% and 6.9% for low and high samples, respectively, and inter-assay CVs were 4.1% and
11.1%. C. Munro at the University of California, Davis provided enzyme-immunoassay
reagents for cortisol assays. Cortisol protocols followed Muller et al. (2007) and Kahlenberg
et al. (2008). Intra-assay CVs were 5.4 and 9.5% for low and high samples, respectively, and
inter-assay CVs were 13.3% and 9.6%. Assay sensitivities were approximately 10 pg/ml for
C-peptide and 300 pg/ml for cortisol. We standardized all hormonal values for concentration
by using creatinine measurements. While cortisol shows circadian variation in secretion
(Muller and Lipson 2003; Anestis and Bribiescas 2004), there was no need to time-adjust the
cortisol values because all urine samples for this study were first-morning voids collected
within a narrow time-window (5:00 – 6:20 am).
SUPPLEMENTARY REFERENCES
Anestis SF, Bribiescas R (2004) Rapid changes in chimpanzee (Pan troglodytes) urinary
cortisol excretion. Horm Behav 45:209-213
2
Emery Thompson M, Knott CD (2008) Urinary C-peptide of insulin as a non-invasive marker
of energy balance in wild orangutans. Horm Behav 53:526-535
Emery Thompson M, Muller MN, Wrangham RW, Lwanga JS, Potts KB (2009) Urinary Cpeptide tracks seasonal and individual variation in energy balance in wild
chimpanzees. Horm Behav 55:299-305
Kahlenberg SM, Thompson ME, Muller MN, Wrangham RW (2008) Immigration costs for
female chimpanzees and male protection as an immigrant counterstrategy to
intrasexual aggression. Anim Behav 76:1497-1509
Knott CD (1997) Field collection and preservation of urine in orangutans and chimpanzees.
Trop Biodiv 4:95-102
Muller M, Lipson S (2003) Diurnal patterns of urinary steroid excretion in wild chimpanzees.
Am J Primatol 60:161-166
Muller M, Wrangham RW (2004) Dominance, cortisol and stress in wild chimpanzees (Pan
troglodytes schweinfurthii). Behav Ecol Sociobiol 55:332-340
Muller M, Kahlenberg S, Emery Thompson M, Wrangham R (2007) Male coercion and the
costs of promiscuous mating for female chimpanzees. P Roy Soc B –Biol Sci
274:1009-1014
Sherry DS, Ellison PE (2007) Potential applications of urinary C-peptide of insulin for
comparative energetics research. Am J Phys Anthropol 133:771-778
3