Ranging behavior of eastern hoolock gibbon (Hoolock leuconedys) in a northern montane forest in Gaoligongshan, Yunnan, China

Exposure to violence, adverse life events and the mental health of adolescent girls in Nairobi slums

INTRODUCTION

Mental health problems rank among the leading causes of disability among young people globally. Young people growing up in urban slums are exposed to adverse childhood experiences, violence, and other adversities. There is limited research on how exposure to violence and adverse life events influence adolescents' mental health in urban poor settings. This study examines the associations between exposure to violence, adverse life events and self-reported depression in the slums of Nairobi.

METHODS

This study draws on data collected from 2106 adolescent girls aged 12-19 years who were interviewed in the third wave of the Adolescent Girls Initiative Kenya (AGI-K). Mental health was measured using the Patient Health Questionnaire (PHQ 9). Frequency distributions, bivariate chi-squared analysis and multi-variate regression models were computed to identify factors that are independently associated with depression.

RESULTS

About 13.3% of girls had symptoms of depression based on PHQ 9, 22% reported physical or sexual violence in the past year and about 47% of girls reported exposure to adverse life events in the family in the past year. After adjusting for the effects of socio-demographic factors, exposure to physical violence (AOR = 2.926, 95% CI 2.175-3.936), sexual violence (AOR = 2.519, 95% CI 1.637-3.875), perception of neighborhood safety (AOR = 1.533, 95% CI 1.159-2.028) and experience of adverse life events (AOR = 1.326, 95% CI 1.002-1.753) were significantly associated with self-reported depression. The presence of social support moderated the relationship between violence and mental health by reducing the strength of the association between violence and mental health in this setting.

CONCLUSION

Given the magnitude of violence victimisation, adverse life events and depressive symptoms, there is a need to design interventions that reduce exposure to violence and provide psychosocial support to adolescents exposed to adverse events in urban slums in Nairobi.

Where to sleep next? Evidence for spatial memory associated with sleeping sites in Skywalker gibbons (Hoolock tianxing)

Finding suitable sleeping sites is highly advantageous but challenging for wild animals. While suitable sleeping sites provide protection against predators and enhance sleep quality, these sites are heterogeneously distributed in space. Thus, animals may generate memories associated with suitable sleeping sites to be able to approach them efficiently when needed. Here, we examined traveling trajectories (i.e., direction, linearity, and speed of traveling) in relation to sleeping sites to assess whether Skywalker gibbons (Hoolock tianxing) use spatial memory to locate sleeping trees. Our results show that about 30% of the sleeping trees were efficiently revisited by gibbons and the recursive use of trees was higher than a randomly simulated visiting pattern. When gibbons left the last feeding tree for the day, they traveled in a linear fashion to sleeping sites out-of-sight (> 40 m away), and linearity of travel to sleeping trees out-of-sight was higher than 0.800 for all individuals. The speed of the traveling trajectories to sleeping sites out-of-sight increased not only as sunset approached, but also when daily rainfall increased. These results suggest that gibbons likely optimized their trajectories to reach sleeping sites under increasing conditions of predatory risk (i.e., nocturnal predators) and uncomfortable weather. Our study provides novel evidence on the use of spatial memory to locate sleeping sites through analyses of movement patterns, which adds to an already extensive body of literature linking cognitive processes and sleeping patterns in human and non-human animals.

Chimpanzee ranging responses to fruit availability in a high-elevation environment

Most primates experience seasonal fluctuations in the availability of food resources and face the challenge of balancing energy expenditure with energy gain during periods of resource scarcity. This is likely to be particularly challenging in rugged, montane environments, where available energy is relatively low and travel costs are high. Chimpanzees (Pan troglodytes) show extensive behavioral diversity across study sites. Yet, as most research has focused on low- and mid-elevation sites, little is known on how chimpanzees respond to periods of low fruit availability in harsh montane environments. We use focal follow and phenology data to investigate how fruit availability influences daily path length and monthly home range in chimpanzees living in Nyungwe National Park, a montane forest in Rwanda. Nyungwe chimpanzees decreased their daily travel distances during periods of fruit scarcity. However, this decrease in travel effort did not correspond with a decrease in foraging area. Instead, monthly homes ranges shifted location across the study period. Nyungwe chimpanzees occupy a relatively wide altitudinal range and the shifts in monthly home range location may reflect differences in the altitudinal distribution of food resources. Chimpanzee monthly diet was often dominated by one or two species and each of these species were confined to different elevation zones. One important species, Podocarpus latifolius, grew only at high elevations (2,600-2,950 m) and chimpanzees ranged at the altitudinal peak of their range for 2 consecutive months while feeding on this species. Thus, while high elevations are often thought to be harsh environments for primates, they can be an important part of a species' home range when they provide a refugium for densely distributed, important food species.

Home range variation of two different-sized groups of golden snub-nosed monkeys (Rhinopithecus roxellana) in Shennongjia, China: implications for feeding competition

Knowledge on the home range size of a species or population is important for understanding its behavioral and social ecology and improving the effectiveness of conservation strategies. We studied the home range size of two different-sized groups of golden snub-nosed monkeys (Rhinopithecus roxellana) in Shennongjia, China. The larger group (236 individuals) had a home range of 22.5 km2 from September 2007 to July 2008, whereas the smaller group (62 individuals) occupied a home range of 12.4 km2 from November 2008 to July 2009. Both groups exhibited considerable seasonal variation in their home range size, which was likely due to seasonal changes in food availability and distribution. The home range in any given season (winter, spring, summer, or winter+spring+summer) of the larger group was larger than that of the smaller group. As the two groups were studied in the same area, with the confounding effects of food availability thus minimized, the positive relationship between home range size and group size suggested that scramble feeding competition increased within the larger group.

Ecology and social system of northern gibbons living in cold seasonal forests

Gibbons in China represent the northernmost margin of present day gibbon species distribution (around N25°). Compared to tropical habitats, northern gibbon habitats are characterized by low temperatures and remarkable seasonal variation in fruit abundance. How gibbons adapt to their cold and seasonal habitats and what ecological factors affect their sociality are key questions for understanding their ecology and social system evolution, the elucidation of which will contribute to the conservation of these special populations/species. According to preliminary short-term studies, northern gibbons consume more leaves and use larger home ranges than tropical gibbons. Interestingly, some Nomascus groups consist of more than one adult female. However, these preliminary results are not well understood or incorporated into current socio-ecological theories regarding gibbon species. To better understand northern gibbons, our team has systematically studied three habituated groups of Nomascus concolor, three groups of N. nasutus, and two habituated groups of Hoolock tianxing since 2002. In this paper, we stress the challenges facing gibbons living in northern habitats and summarize their behavioral adaptations to their harsh environments. We also describe the northern gibbon social system and discuss the potential relationships between their ecology and sociality. Finally, we highlight future research questions related to northern gibbons in China.

Effects of group density, hunting, and temperature on the singing patterns of eastern hoolock gibbons (Hoolock leuconedys) in Gaoligongshan, Southwest China

Many non-human primates produce species-specific loud calls to communicate within and between groups over long distances. Understanding these calling patterns can provide insights into how individuals modify their behavior in response to environmental variables as well as help to design efficient bioacoustic survey techniques. Eastern hoolock gibbons in Gaoligongshan inhabit the coldest habitat of all gibbon populations, but both conservation and research efforts on this population have been minimal. We studied singing patterns of two habituated and two unhabituated groups at two sites in Gaoligongshan between July 2010 and June 2015. We systematically collected data of their calls, and its relationship to temperature, group density, and hunting pressure over at least 1 year for each group. Our goal was to elucidate how these factors affect singing patterns of eastern hoolock gibbons. We found that adult pairs coordinated their singing to produce duet bouts that lasted for an average of 25.5 min. The singing rate (number of bouts/number on monitoring days*100%: 7.5-31.4%) was notably lower than other gibbon populations, presumably due to low group density (about 0.5 groups/km(2) ) and prevalence of hunting at the study site. Cold temperature also affected gibbons' singing behavior. Our study groups called, on average, 2.5 hr after sunrise, probably foraging first in the early morning after long nights in this cold habitat delayed singing. Furthermore, mean temperatures in the morning (8:00-12:00 am) were higher on singing days than on non-singing days, and one group called less frequently when monthly mean temperature was below 10°C. Our findings indicate that both hunting pressure from humans and low temperatures suppress calling behavior in hoolock gibbons. Such information is critical in evaluating the use of duetting as a monitoring technique for this endangered gibbon species. Am. J. Primatol. 78:861-871, 2016. © 2016 Wiley Periodicals, Inc.

Effects of tsaoko (Fructus tsaoko) cultivating on tree diversity and canopy structure in the habitats of eastern hoolock gibbon (Hoolock leuconedys)

In this study, the quadrat method was used to study the effects of tsaoko (Fructus tsaoko) plantation on tree diversity and canopy structure of two natural habitats of eastern hoolock gibbon (Hoolock leuconedys): Nankang (characterized by extensive tsaoko plantation) and Banchang (relatively well reserved and without tsaoko plantation). Totally, 102 tree species from 25 families and 16 woody liana species from 10 families were recorded in Nankang, whereas 108 tree species from 30 families and 17 woody liana species from 12 families were recorded in Banchang. Although the tree species between two habitats is different, both habitats are characterized by enriched food resources for eastern hoolock gibbons, sharing similar dominant plant families. Due to tsaoko plantation, tree density proportion and diversity of forest layerⅠ (>20 m) in Nankang were both significantly decreased, but the tree density of layerⅡ (10-20 m) increased. Likewise, in conjunction with these behavioral observations, we also address potential impacts of tsaoko plantation on the behavior of eastern hoolock gibbon.