Publications

hand preferences in captive gorillas, orang-utans and gibbons.	hand preference was assessed in 12 gorillas (gorilla gorilla gorilla), 13 orang-utans (pongo pygmaeus abelii), and 9 gibbons (hylobates lar) by using a floor retrieval task and a mesh retrieval task. hand preference was also assessed in 8 gorillas and 8 orang-utans by using a task involving the unfastening of a hasp. a bipedal requirement during testing (mesh retrieval task) facilitated detection of hand preferences. a significant left-hand preference was found for the gibbons with 6 of 6 gibbon ...	1990	31963993
do line-transect surveys systematically underestimate primate densities in logged forests?	the rate at which social groups of primates are encountered in disturbed rain forest may be biased relative to undisturbed rain forest. a recently reported case study revealed a 25% reduction in postlogging raw encounter rates even though the true density of primates remained at the prelogging level. if biased raw encounter rates are typical of disturbed forests, and if they translate into equally biased line-transect density estimates, results of many comparative surveys might prove misleading ...	1987	31973482
songs of hybrid gibbons (hylobates lar × h. muelleri).	two hybrid offspring, one male and one female, were produced by a hylobates muelleri female mated to a hylobates lar male at micke grove zoo, lodi, california. songs of the hybrids were studied at adulthood and compared to the parental-type songs. the hybrid female song is uniquely different from either parental type. the hybrid male song resembles the male song of h. lar, but contains an element that may be unique to h. muelleri. the study demonstrates the utility of sound-spectographic analysi ...	1985	31986810
differential detectability of primates between primary and selectively logged habitats and implications for population surveys.	much information has been published concerning the accurary of various techniques commonly used for censusing primates. the sources of bias may vary according to the technique used. accuracy may depend on population density as well as on differential visibility and hence detectability between areas. this paper provides evidence that primates may alter their behavior between areas of primary and selectively logged habitat, which in turn could affect census results. adoption of cryptic behavior, c ...	1985	31986823
one-armed brachiation in gibbons (hylobates lar).	the locomotor and postural behavior of hylobates lar was studied in a seminaturalistic environment at the new york zoological park. a particular locomotor pattern, one-armed brachiation, was observed and filmed. analysis indicated that the occurrence of one-armed brachiation as a preferred locomotor pattern was rare and was limited to the carrying of food. the limb and joint movements of one-armed brachiation closely resembled those of two-armed brachiation with differences occurring in the angu ...	1982	31991983
are social media reports useful for assessing small ape occurrence? a pilot study from peninsular malaysia.	citizen science-based research has been used effectively to estimate animal abundance and breeding patterns, to monitor animal movement, and for biodiversity conservation and education. here, we evaluate the feasibility of using social media observations to assess the distribution of small apes in peninsular malaysia. we searched for reports of small ape observations in peninsular malaysia on social media (e.g., blogs, facebook, instagram, twitter, youtube, inaturalist, etc.), and also used onli ...	2020	32083333
acute human orthopneumovirus infection in a captive white-handed gibbon.	we report herein a fatal case of acute human orthopneumovirus (formerly respiratory syncytial virus) infection in a captive white-handed gibbon (hylobates lar). other members of the housing group had mild respiratory signs. gross examination revealed bilateral pulmonary congestion and froth in the bronchi. microscopically, the lungs had lymphocytic, neutrophilic infiltration of the interstitium and alveolar walls. there was necrosis of terminal bronchiolar epithelium and terminal bronchioles, an ...	2020	32167415
clonal spread of yersinia enterocolitica 1b/o:8 in multiple zoo species.	yersinia enterocolitica (ye) bioserotype 1b/o:8 (ye 1b/o:8) was identified in routine culture of a variety of zoo species housed at omaha's henry doorly zoo and aquarium (ohdza) from april to july 2011. animal cases representing 12 species had ye detected from 34 cases during routine fecal monitoring and/or during postmortem examination: coquerel's sifakas (propithecus coquereli, two cases), black & white (bw) ruffed lemurs (varecia variegata variegata, six cases), red ruffed lemurs (varecia rub ...	2020	32212560
the forearm and hand musculature of semi-terrestrial rhesus macaques (macaca mulatta) and arboreal gibbons (fam. hylobatidae). part i. description and comparison of the muscle configuration.	primates live in very diverse environments and, as a consequence, show an equally diverse locomotor behaviour. during locomotion, the primate hand interacts with the superstrate and/or substrate and will therefore probably show adaptive signals linked with this locomotor behaviour. whereas the morphology of the forearm and hand bones have been studied extensively, the functional adaptations in the hand musculature have been documented only scarcely. to evaluate whether there are potential adapta ...	2020	32511764
mandibular shape variation in mainland and insular hylobatids.	although hylobatids are the most speciose of the living apes, their morphological interspecies and intraspecies variation remains poorly understood. here, we assess mandibular shape variation in two species of hylobates, white-handed (hylobates lar) and black-handed (hylobates agilis) gibbons. using 71 three-dimensional landmarks to quantify mandibular shape, interspecies and intraspecies variation and geographic patterns of mandibular shape are examined in a mixed sex sample of adult h. lar and ...	2020	32696564
white-handed gibbons discriminate context-specific song compositions.	white-handed gibbons produce loud and acoustically complex songs when interacting with their neighbours or when encountering predators. in both contexts, songs are assembled from a small number of units although their composition differs in context-specific ways. here, we investigated whether wild gibbons could infer the 'meaning' when hearing exemplars recorded in both contexts (i.e. 'duet songs' vs. 'predator songs'). we carried out a playback experiment by which we simulated the presence of a ...	2020	32832260
white-handed gibbons (hylobates lar) alter ranging patterns in response to habitat type.	small apes are often characterized as inhabiting small home ranges and being dependent on evergreen forest due to their dietary specialization on ripe fruits. yet few primate studies, particularly those with gibbons, have considered intraspecific variations in ranging behaviors in response to local ecological conditions. this study examines endangered white-handed gibbon (hylobates lar) ranging patterns in a heterogeneous landscape. we conducted 13 months of behavioral observations on four white ...	2020	32880766
the forearm and hand musculature of semi-terrestrial rhesus macaques (macaca mulatta) and arboreal gibbons (fam. hylobatidae). part ii. quantitative analysis.	nonhuman primates have a highly diverse locomotor repertoire defined by an equally diverse hand use. based on how primates use their hands during locomotion, we can distinguish between terrestrial and arboreal taxa. the 'arboreal' hand is likely adapted towards high wrist mobility and grasping, whereas the 'terrestrial' hand will show adaptations to loading. while the morphology of the forearm and hand bones have been studied extensively, functional adaptations in the forearm and hand musculatur ...	2020	33011967