No abstract

Selection and use patterns of sleeping sites in nonhuman primates are suggested to have multiple functions, such as predation avoidance, but they might be further affected by range defense as well as foraging constraints or other factors. Here, we investigate sleeping tree selection by the male and female members of one group of pileated gibbons (Hylobates pileatus) at Khao Ang Rue Nai Wildlife Sanctuary, Thailand. Data were collected on 113 nights, between September 2006 and January 2009, yielding data on 201 sleeping tree choices (107 by the female and 94 by the male) and on the characteristics of 71 individual sleeping trees. Each sleeping tree and all trees > or =40 cm diameter at breast height (DBH) in the home range were assessed (height, DBH, canopy structure, liana load) and mapped using a GPS. The gibbons preferentially selected tall (mean=38.5 m), emergent trees without lianas. The majority of the sleeping trees (53.5%) were used only once and consecutive reuse was rare (9.5%). Sleeping trees were closer to the last feeding tree of the evening than to the first feeding tree in the morning, and sleeping trees were located in the overlap areas with neighbors less often than expected based on time spent in these areas. These results suggest avoidance of predators as the main factor influencing sleeping tree selection in pileated gibbons. However, other non-mutually exclusive factors may be involved as well.

Several factors are likely to control sleeping site selection and presleep behavior in nonhuman primates, including predation risk and location of food resources. We examined the effects of these factors on the sleeping behavior of northern pigtailed macaques (Macaca leonina). While following a troop living in the surroundings of the Visitor Center of Khao Yai National Park (Thailand), we recorded the physical characteristics and location of each sleeping site, tree, the individuals' place in the tree, posture, and behavior. We collected data for 154 nights between April 2009 and November 2010. The monkeys preferred tall sleeping trees (20.9 ± SD 4.9 m) and high sleeping places (15.8 ± SD 4.3 m), which may be an antipredator strategy. The choice of sleeping trees close to the last (146.7 ± SD 167.9 m) or to the first (150.4 ± SD 113.0 m) feeding tree of the day may save energy and decrease predation risk when monkeys are searching for food. Similarly, the choice of sleeping sites close to human settlements eases the access to human food during periods of fruit scarcity. Finally, the temporal pattern of use of sleeping sites, with a preference for four of the sleeping sites but few reuses during consecutive nights, may be a trade-off between the need to have several sleeping sites (decreasing detection by predators and travel costs to feeding sites), and the need to sleep in well-known sites (guaranteeing a faster escape in case of predator attack).

A three-year (2001-2003) study was carried out on the home range characteristics of seven wild white-handed gibbon (Hylobates lar) groups focusing on the spatio-temporal distribution of food resources at Khao Yai National Park in northeastern Thailand. These results were combined with 23 years (1980-2003) of reproductive performance data on seven females from the same focal groups. Reproductive performance was equal among females with regard to birth, weaning and maturation ratios, and independent of variation in food availability. Offspring mortality, however, was significantly positively correlated with home-range size. In addition, there was an increase in offspring mortality just after weaning, suggesting that the increase in the daily distance traveled by juveniles contributed to this mortality. Conceptions clustered during the first half of the year when food production was at its peak, which presumably allowed females to accumulate sufficient body reserves to resume ovarian cycling. Our results place Khao Yai gibbons closer to Cercopithecidae than great apes in terms of the temporal pattern of reproductive events, though gestation, lactation, inter-birth interval, and offspring maturation are considerably longer in gibbons, placing them closer to the other apes. Our findings underline the unique phylogenetic position of these small-bodied apes in terms of reproductive patterns in primates.

No abstract

Tigers Panthera tigris are highly threatened and continue to decline across their entire range. Actions to restore and conserve populations need to be based on science but, in South-east Asia, information on ecology and behaviour of tigers is lacking. This study reports the relationship between the home range size of female tigers and prey abundance, using data from radio-collared tigers in Huai Kha Khaeng Wildlife Sanctuary, Thailand, and published data from other studies. A total of 11 tigers, four males and seven females, were fitted with global positioning system collars, to estimate home ranges using 95 and 100% minimum convex polygons (MCP). Prey abundance was estimated by faecal accumulation rates. The mean home range size of male tigers was 267 and 294 km 2 based on 95 and 100% MCPs, respectively; the mean female home range size was 70 and 84 km 2 , respectively. Territories of male and female tigers had little overlap, which indicated both sexes were territorial. Mean densities of the prey species sambar Rusa unicolor, barking deer Muntiacus muntjac and large bovids were 7.5, 3.5 and 3.0 km −2 , respectively. When female home range size and prey abundance were compared at six locations in Thailand, and at other sites in India, Nepal, Bangladesh and Russia, a significant negative correlation was found between prey abundance and home range size. Monitoring this relationship can provide managers with metrics for setting conservation goals.

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a b s t r a c tBiodiversity declines in Southeast Asia have led to predictions that many vertebrate species will become extinct within 50 years. Examples of quantified deterioration in species status remain scarce, however. The Southeast Asian geographical range of the Endangered Green peafowl is still contracting due to hunting pressure and habitat disturbance. In Vietnam, the main population lies in the southcentral region with a relatively high density reported in 1998. The aim of this study was to assess the species' current status in Yok Don and Cat Tien National Parks, which are thought to contain the most important Vietnamese populations. We used line and point transects to investigate the density and analyze habitat selection and effects of human activity. The Yok Don population has decreased sharply during the past 15 years, while in Cat Tien, the estimated density was higher. Animals were most numerous close to water sources and lowest where cattle numbers were highest and ground vegetation cover absent. Here we document a significant negative population change in a previously widespread vertebrate species. Although comparisons of population data over long periods are rare, we demonstrate that taking advantage of opportunities to resurvey species can quantify population declines.