Wenxuan Xu

Grouping pattern of the goitered gazelle, Gazella subgutturosa (Cetartiodactyla: Bovidae) in Kazakhstan

Abstract The group size and composition of goitered gazelles were investigated over several years in Kazakhstan. Most gazelles formed groups of one to three individuals all year round. This small herd size recorded in our study area was probably a consequence of the feeding ecology of the goitered gazelle, which is a very selective ruminant of small body size. With respect to group composition, female and male groups were the most often noted (52.0% and 37.9%), while mixed herds and groups of yearlings were considerably rarer (4.6% and 5.5%). Moreover, mixed groups were the largest groups (mean±SE: 5.29±0.25 individuals per group), followed by female groups (2.40±0.03), male groups (2.14±0.05), and yearling herds (1.49±0.05). In addition, the grouping pattern varied seasonally and corresponded very closely to the yearly breeding cycle of the goitered gazelle. Nevertheless, it remains consistent with what is known of the grouping pattern of other gazelles.

Seasonal diet of Khulan (Equidae) in Northern Xinjiang, China

Abstract The natural diet of khulan (Equus hemionus Pallas, 1775) was observed over the period of a year in northern Xinjiang, China, using faecal analysis. The winter food habits of the khulan and domestic sheep were also compared. The faecal analysis method demonstrated that khulan ate 46 species of plants during the year. Diets varied seasonally, with the widest food breadth in winter (0.43) and the least in summer (0.10). Chenopodiaceae and Poaceae were major foods of khulan, and during spring, forbs were quite important as well. In contrast, Stipa glareosa was preferred during spring and summer, but consumed less during autumn and winter. Shrubs dominated the khulans natural diet during autumn and winter. The dietary overlap between khulan and domestic sheep was 48.3% during winter. As a grazer living in arid environments, khulan ate more shrubs than other equids living in grassland, and their winter diet was an adaptation to avoid competition from domestic sheep. The number of sheep in the reserve should be reduced to lessen the pressure of competition.

Diurnal time budget of goitred gazelles (Gazella subgutturosa Güldenstaedt, 1780) in Xinjiang, China

Abstract It is considered that four factors influence ungulate activity budget: (a) seasonal biomass and quality, (b) temperature, (c) yearly life cycle, and (d) livestock movements and human activity. In order to test them, the diurnal time budget of goitred gazelles was studied using the focal sampling method in Xinjiang Province (China) during a two-year period (2007–2009). According to our results, in all seasons goitred gazelles spent more than half (up to 68.9%) of their daytime feeding on pastures, and more than one-third resting in spring, autumn, and especially summer (up to 42.1%); in winter their resting time decreased to 29.0% for males and 19.0% for females. Though other activities were very important in the gazelles’ lives, the diurnal time budget for these activities was low (<8.0%). Goitred gazelles showed a trimodal feeding activity in most seasons, and a bimodal in summer (females). Females in summer and males during rutting season devoted more significant time to other activities (suckling, moving, courting and agonistic behaviour). However, the portion of time was still notably lower than for feeding and resting.

Seasonal and sexual variation in vigilance behavior of goitered gazelle (Gazella subgutturosa) in western China

Animals receive benefits from social behavior. As part of a group, individuals spend less time having to be vigilant. This phenomenon, called the “group size effect,” is considered the most dominant factor in an animal’s demonstrated level of vigilance. However, in addition to group size, many other social and environmental factors also influence the degree of vigilance, including the season of the year and the sex of the individual. In our study, we examined the vigilant behavior of goitered gazelles in the Xinjiang Province in western China to test whether and how seasons, the yearly breeding cycle, and group size affect vigilance. According to our results, we found that seasonal factors were not a substantial influence on a gazelle’s level of vigilance, while group size had a tangible effect. In comparison, the yearly breeding cycle (a natural phenomenon) was the most powerful factor: it significantly changed the degree of vigilance in females during birthing and males during rut. Anthropogenic factors (unnatural phenomena) were also potential causes of increased vigilance in both sexes during winter.

Human Activity Dampens the Benefits of Group Size on Vigilance in Khulan (Equus hemionus) in Western China.

Animals receive anti-predator benefits from social behavior. As part of a group, individuals spend less time being vigilant, and vigilance decreases with increasing group size. This phenomenon, called “the many-eyes effect”, together with the “encounter dilution effect”, is considered among the most important factors determining individual vigilance behavior. However, in addition to group size, other social and environmental factors also influence the degree of vigilance, including disturbance from human activities. In our study, we examined vigilance behavior of Khulans (Equus hemionus) in the Xinjiang Province in western China to test whether and how human disturbance and group size affect vigilance. According to our results, Khulan showed a negative correlation between group size and the percentage time spent vigilant, although this negative correlation depended on the groups’ disturbance level. Khulan in the more disturbed area had a dampened benefit from increases in group size, compared to those in the undisturbed core areas. Provision of continuous areas of high-quality habitat for Khulans will allow them to form larger undisturbed aggregations and to gain foraging benefits through reduced individual vigilance, as well as anti-predator benefits through increased probability of predator detection.

The energy-maintenance strategy of goitered gazelles Gazella subgutturosa during rut

In many polygynous ruminant species, males decrease their food intake considerably during the rut. To explain this phenomenon of rut-reduced hypophagia, two main hypotheses, the Foraging-Constraint Hypothesis and Energy-Saving Hypothesis, have been proposed. In our research, we assessed the behavioral strategy of goitered gazelles (Gazella subgutturosa) through the rutting period. According to our findings, male goitered gazelles spent less time feeding during the rut compared to pre- and post-rut feeding times, but then maximized their energy intake during the rutting season when they were not engaged in rut-related behaviors. Females, in contrast, did not change their time budgets across the different stages of the rut. Therefore, rut-induced hypophagia is mainly arising from the constraints of rut-related behaviors for male goitered gazelles, so that the Foraging-Constraint Hypothesis better explains their strategy during rut.

Diet characteristics of wild sheep ( Ovis ammon darwini ) in the Mengluoke Mountains, Xinjiang, China

In most arid and semi-arid regions of the world, domestic livestock and native wildlife share pastures, and their competition for forage and habitat is thought to be a serious conservation issue. Moreover, unmanaged grazing by livestock can cause the population decline in wild ungulates. The diet of an animal species is a determining aspect of its ecological niche, and investigating its diet has been one of the initial steps in basic ecology study of a new species. To get an approximate understanding of the interspecific food relationships of argali (Ovis ammon darwini) between sexes, and sympatric domestic sheep and goats, we compared the diet compositions and diet-overlaps among these herbivores, i.e., male argali, female argali, domestic sheep, and domestic goats in the Mengluoke Mountains of Xinjiang, China by using micro-histological fecal analysis. Female argali, male argali, domestic sheep and domestic goat primarily consumed forbs (43.31%±4.86%), grass (36.02%±9.32%), forbs (41.01%±9.18%), and forbs (36.22%±10.61%), respectively in warm season. All these animals consumed mostly shrubs (female argali: 36.47%±7.56%; male argali: 47.28%±10.75%; domestic sheep: 40.46%±9.56%; and domestic goats: 42.88%±9.34%, respectively) in cold season. The diet-overlaps were relatively high among all species in cold season with values ranging from 0.88 to 0.94. Furthermore, Schoener’s index measured between each possible pair of 4 herbivores increased from the warm season to the cold season. The results illustrate that the high degree of diet-overlap of argali and domestic livestock (sheep and goat) may pose a threat to the survival of the argali in cold season. From the viewpoint of rangeland management and conservation of the endangered argali, the numbers of domestic sheep and goats should be limited in cold season to reduce food competition.

Sexual segregation in the Darwin's wild sheep, Ovis ammon darwini, (Bovidae, Artiodactyla), in the Mengluoke Mountains of Xinjiang, China

Abstract. Sexual segregation has been found among many vertebrate species. Argali, like other sexually dimorphic Capridae, form sexually segregated groups outside the breeding season. The degree of sexual segregation and its seasonal changes have never been examined and quantified in Asiatic species of wild sheep. In this paper we are considering seasonal fluctuation in the degree of sexual segregation and check the activity budget hypothesis to explain this phenomenon in the Darwins wild sheep (Ovis ammon darwini), a subspecies of argali sheep (Ovis ammon). The activity budget hypothesis states that sexually size-dimorphic males and females segregate into different groups due to incompatibilities in activity budgets and movement rates. We collected data on activity budgets in the argali sheep from 2015 to 2016, in the Mengluoke Mountains of Xinjiang Province, and used Conradts segregation coefficient (SC) to measure the degree of sexual segregation outside and during the rutting seasons. Our results showed that the SC value was highest outside the rutting season (0.98), when argalis were almost completely segregated. During the rutting period, the segregation coefficient dropped more than twofold (0.43) compared to the non-rutting season. In addition, our data supported the activity budget hypothesis: female and male argali had different behavioural activity patterns during the non-rutting season. Female argali spent more time feeding, followed by resting, standing, moving, and other behaviours, while males spent most of their time resting, followed by feeding, standing, other behaviours, and moving. Female argali spent significantly more time feeding than males, while males spent significantly more time resting and in other behaviours than females. Activity synchronization indices for both female groups and male groups were significantly higher than in mixed-sex groups. Sexual segregation is the best behavioural strategy for sexually dimorphic ungulates and the activity budget hypothesis explained this phenomenon well in Darwins wild sheep.

Impact of great gerbils (Rhombomys opimus) on desert plant communities

Great gerbil (Rhombomys opimus) colonies, with bare soil and herbaceous plants, are conspicuous to the background environment throughout their range area. In order to quantify the engineer role of great gerbils, we investigated the plant communities of 20 active colonies in the Junggar Basin, Xinjiang, China. In areas without disturbance, desert plant communities were dominated by the shrubs with low level species richness. In burrow areas and surrounding intermediate areas, which were disturbed by great gerbils, the shrubs were suppressed with the decrease of vegetation cover and aboveground biomass. As a result, “niche gaps” were created in disturbed areas and worked as a refuge for herbaceous annuals and perennials. So the existence of great gerbils increased the overall species richness of the desert. Furthermore, herbaceous annuals and perennials are the major food source for great gerbils in spring, indicating that great gerbils have a mutually beneficial relationship with herbaceous plants.