| a behavioural case study of early social isolation of a subadult white-handed gibbon (hylobates lar). | our aim in this study was to analyse the effects of early social isolation on the behaviour of a white-handed gibbon (hylobates lar) and at the same time to improve his level of welfare. the subject was a 6-year-old male, isolated from conspecific as well as other non-human primates since he was 3 months old. we presented the gibbon with a series of species-specific vocalisations, and we then introduced a 23-year-old conspecific female into his cage. our subject did not respond to playbacks, whe ... | 2018 | 29874638 |
| short dispersal distance of males in a wild white-handed gibbon (hylobates lar) population. | it has long been recognized that in gibbons both sexes disperse from the natal group. however, the fate of dispersed individuals was rarely documented. here we provide the first detailed information on sex differences in dispersal patterns by analyzing the spatial genetic structure of a well-known white-handed gibbon (hylobates lar) population. | 2018 | 29737526 |
| an analysis of white-handed gibbon male song reveals speech-like phrases. | our goal was to document song phrases of the white-handed gibbon (hylobates lar), an asian ape that produces elaborate songs, often in well-coordinated male/female duets. we focused on the male coda, which is produced during vocal turn-taking with one's mate, and particularly its phrases containing rapid spectral and temporal variation, to investigate if modulation rates resemble those of lip-smacking in other nonhuman primates and human speech rhythm. | 2018 | 29508909 |
| assessment of environmental enrichment for different primate species under low budget: a case study. | the 2011 european union zoo inquiry presented evidence that most zoos fail to achieve adequate levels of nonhuman animal welfare. appropriate environmental enrichment (ee) can play a role in the promotion of welfare. however, financial and staff constraints frequently make it challenging to implement ee on a daily basis. the aim of this study was to test how individuals of three different nonhuman primate species at the maia zoo in portugal (white-handed gibbons, hylobates lar; mona monkeys, cer ... | 2018 | 29299937 |
| neonatal weight in gibbons (hylobates spp.). | neonatal and birth weights of gibbons have mostly been reported for single individuals, and larger samples (n = 2-8) have apparently been published for only two species of gibbons (hylobates lar and h. syndactylus). in addition, a critical examination of the few published neonatal weights of gibbons shows that several of them should not be used. neonatal weights are here defined as weights taken on infants up to seven days old, whereas birth weights include only those taken on the day of birth. ... | 1995 | 31936947 |
| ontogeny and the evolution of adult body size dimorphism in apes. | this analysis investigates the ontogeny of body size dimorphism in apes. the processes that lead to adult body size dimorphism are illustrated and described. potential covariation between ontogenetic processes and socioecological variables is evaluated. mixed-longitudinal growth data from 395 captive individuals (representing hylobates lar [gibbon], hylobates syndactylus [siamang], pongo pygmaeus [orangutan], gorilla gorilla [gorilla], pan paniscus [pygmy chimpanzee], and pan troglodytes ["commo ... | 1995 | 31924084 |
| lethal territorial aggression in a white-handed gibbon. | during an intergroup conflict an adult male white-handed gibbon (hylobates lar) from one group was attacked and wounded by the adult male of a neighboring group. the wounded male's calling behavior, general activity level, feeding, and participation in territorial defense declined dramatically in the days following the injury as he instead spent long periods resting and tending the wound. the normal and healthy appearance of this male prior to injury, the circumstances of the fight that caused t ... | 1993 | 31936991 |
| reassessment of age of sexual maturity in gibbons (hylobates spp.). | from studies of both wild and captive animals, gibbons are thought to reach sexual maturity at about 6 to 8 years of age, and the siamang (hylobates syndactylus) at about 8 to 9 years. however, a review of the literature reveals that in most cases the exact age of the maturing animals was not known and had to be estimated. this study presents seven case reports on captive gibbons of known age. captive males of the white-cheeked crested gibbon (h. leucogenys leucogenys) and of the siamang (h. syn ... | 1991 | 31952414 |
| 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 |
| 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 |
| 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 |
| 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 |