Brief communication: Weights of wild orang utans

Markham, R. J. Frederick; Groves, Colin P.

doi:10.1002/ajpa.1330810102

Cited by 55 publications

(37 citation statements)

References 8 publications

(19 reference statements)

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“…The growth curve for captive orangutans (Fig. 2) supports the conclusions of Markham and Groves (1990) that adult orang-utans weigh about 86 kg and that Schultz (1938) documented immature individuals only. Moreover, 2 captive Bornean individuals that died of ill health at 67 kg and 76 kg were found to be emaciated and, hence, close to or at their minimum viable body weight (Swenson, pers.…”

Section: Discussionsupporting

confidence: 71%

“…Attaining a size of 80 kg or above may either be a prerequisite for establishing a territory or consequent to it. Hence, the body weight for adult, male orang-utans for a majority of their breeding life may well be about 85 kg or larger as indicated by Markham and Groves (1990) from a consideration of 5 individuals only. It follows that the testicle weight:body weight ratio characteristic of orang-utans with a fully mature stature is probably about 0.035, but varies widely.…”

Section: Discussionmentioning

confidence: 98%

“…Not only is the size of the testicles for Pongo poorly known, but body weight for fully adult males is also reported for few individuals, both from captivity (Courtenay et al, 1988), where individuals are noted to become obese, and from the wild (Markham and Groves, 1990). Markham and Groves (1990), moreover, question the maturity of all specimens of Pongo examined by Schultz (1938).…”

mentioning

confidence: 93%

“…Markham and Groves (1990), moreover, question the maturity of all specimens of Pongo examined by Schultz (1938). Body weight for a representative sample of captive individuals through a wide range of ages is documented here to establish maturity in captive subjects, and the weight of fully adult subjects was compared to that of wild specimens (Markham and Groves, 1990).…”

mentioning

confidence: 99%

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Testicle size of orang‐utans in relation to body size

Dahl

Gould

Nadler

1993

American J Phys Anthropol

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Few data are available for assessing the relative testicle size of orang-utans, Pongo pygmaeus, so measures were obtained for 31 individuals of varying age. It was shown that the volume of the testicles, calculated from in situ measures of testicle length and breadth, closely approximates testicle weight when multiplied by the specific gravity of solid tissue. Growth curves for body weight and data published for wild specimens were evaluated to obtain the weight most characteristic of male Pongo, and the ratio of testicle weight to body weight was calculated. The mean ratio for individuals with fully adult stature is 0.034, similar to but smaller than that of humans at about 0.050, and larger than the ratios reported for 5 gorillas at 0.013. The testicles mature faster than the body, however, so the mean ratio for young adult orang-utans is about 0.056 and resembles the ratio for humans more closely than the full adults. The differences between the ratios for a monogamous gibbon species, orang-utans, and humans is accounted for when testicle size relative to the weight of the female is considered. This is consistent with a sperm dilution effect produced by variation in the size of the female reproductive tract. The small relative testicle size of the gorilla is anomalous and requires verification as does the application of female size to scale the testicles.

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Section: Discussionsupporting

confidence: 71%

Section: Discussionmentioning

confidence: 98%

mentioning

confidence: 93%

mentioning

confidence: 99%

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Testicle size of orang‐utans in relation to body size

Dahl

Gould

Nadler

1993

American J Phys Anthropol

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“…Wild orangutan body mass has been estimated at 38.7 kg for adult females and 86.3 kg for flanged males (Markham and Groves 1990). Wild unflanged male body mass has not been documented, but, based on our observations in the field, we estimate it to be closer to that of adult females than flanged males and probably ca.…”

Section: Estimating Energy Requirementsmentioning

confidence: 65%

Orangutan Energetics and the Influence of Fruit Availability in the Nonmasting Peat-swamp Forest of Sabangau, Indonesian Borneo

2010

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Data on energy intake and the effects of fluctuations in fruit availability on energy intake for African apes, and orangutans in mast-fruiting habitats, indicate that orangutans may face greater energetic challenges than do their African counterparts. Comparable data on orangutans in nonmasting forests, which experience lower fluctuations in fruit availability, have been lacking, however, complicating interpretations. We conducted a 46-mo study of orangutan energetics in the nonmasting Sabangau peat-swamp forest, Indonesian Borneo. Sabangau orangutans experienced periods of negative energy balance apparently even longer than in mastfruiting habitats, as indicated by comparisons of observed energy intake with theoretical requirements and analysis of urinary ketones. Daily energy intake was positively related to fruit availability in flanged males, but not in adult females or unflanged males. This may represent different foraging strategies between age-sex classes and suggests that fruit availability is not always an accurate indicator of ape energy intake/balance. Urinary ketone levels were not generally related to fruit availability, daily energy intake, day range, or party size. This is probably due to low energy intake, and consequently high ketone production, throughout much of the study period. Comparisons with published results on African apes support the hypothesis that orangutans are unique among hominoids in regularly experiencing prolonged periods of negative energy balance. This has important effects on orangutan behavior and socioecology, and has likely been a key factor driving the evolutionary divergence of orangutans and African apes.

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Intrasexual competition and body weight dimorphism in anthropoid primates

Plavcan

Schaik

1997

Am. J. Phys. Anthropol.

275

192

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Body weight dimorphism in anthropoid primates has been thought to be a consequence of sexual selection resulting from male-male competition for access to mates. However, while monogamous anthropoids show low degrees of weight dimorphism, as predicted by the sexual selection hypothesis, polygynous anthropoids show high variation in weight dimorphism that is not associated with measures of mating system or sex ratio. This observation has led many to debate the role of other factors such as dietary constraints, predation pressure, substrate constraints, allometric effects, and phylogeny in the evolution of anthropoid weight dimorphism. Here, we re-evaluate variation in adult body weight dimorphism in anthropoids, testing the sexual selection hypothesis using categorical estimates of the degree of male-male intrasexual competition ("competition levels"). We also test the hypotheses that interspecific variation in body weight dimorphism is associated with female body weight and categorical estimates of diet, substrate use, and phylogeny. Weight dimorphism is strongly associated with competition levels, corroborating the sexual selection hypothesis. Weight dimorphism is positively correlated with increasing female body weight, but evidence suggests that the correlation reflects an interaction between overall size and behavior. Arboreal species are, on average, less dimorphic than terrestrial species, while more frugivorous species tend to be more dimorphic than folivorous or insectivorous species. Several alternative hypotheses can explain these latter results. Weight dimorphism is correlated with taxonomy, but so too are competition levels. We suggest that most taxonomic correlations of weight dimorphism represent "phylogenetic niche conservatism"; however, colobines show consistently low degrees of weight dimorphism for reasons that are not clear.

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Brief communication: Weights of wild orang utans

Cited by 55 publications

References 8 publications

Testicle size of orang‐utans in relation to body size

Testicle size of orang‐utans in relation to body size

Orangutan Energetics and the Influence of Fruit Availability in the Nonmasting Peat-swamp Forest of Sabangau, Indonesian Borneo

Intrasexual competition and body weight dimorphism in anthropoid primates

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