Effect of Large Wild Herbivore Populations on the Forage-Livestock Balance in the Source Region of the Yellow River

Using the Yellow-River-Source National Park (YRSNP) as a study site, an unmanned aerial vehicle (UAV) remote sensing and line transect method was used to investigate the number of wild herbivorous animals and livestock, including the kiang (Equus kiang) and Tibetan gazelle (Procapra picticaudata). A downscaling algorithm was used to generate the forage yield data in YRSNP based on a 30-m spatial resolution. On this basis, we estimated the forage–livestock balance, which included both wild animals and livestock, and analyzed the effects of functional zone planning in national parks on the forage–livestock balance in YRSNP. The results showed that the estimates of large herbivore population numbers in YRSNP based on population density in the aerial sample strips, which were compared and validated with official statistics and warm season survey results, indicated that the numbers of kiangs and Tibetan gazelles in the 2017 cold season were 12,900 and 12,100, respectively. The numbers of domestic yaks, Tibetan sheep, and horses were 53,400, 76,800, and 800, respectively, and the total number of sheep units was 353,200. The ratio of large wild herbivores and livestock sheep units was 1:5. Large wild herbivores have different preferences for functional zones, preferring ecological restoration areas consisting mainly of sparse grassland. The grazing pressure indices of the core reserve areas and ecological restoration areas were 0.168 and 0.276, respectively, indicating that these two regions still have high grazing potential. However, the grazing pressure index of the traditional utilization areas was 1.754, indicating that these grasslands are severely overloaded. After the planning and implementation of functional zones, the grazing pressure index of YRSNP was 1.967. Under this measure, the number of livestock was not reduced and the grazing pressure nearly doubled, indicating that forage–livestock conflict has become more severe in YRSNP.

We used unmanned aerial vehicles (UAVs) to carry out a relatively complete population census of large wild herbivores in Maduo County on the Tibetan Plateau in the spring of 2017. The effective area covered by aerial surveys was 326.6 km2, and 23,784 images were acquired. Interpretation tag libraries for UAV images were created for wild animals, including Kiang (Equus kiang), Tibetan gazelle (Procapra picticaudata), and blue sheep (Pseudois nayaur), as well as livestock, including yaks and Tibetan sheep. Large wild herbivores in the survey transect were identified through manual imagery interpretation. Densities ranged from 1.15/km2 for Kiang, 0.61/km2 for Tibetan gazelle, 0.62/km2 for blue sheep, 4.12/km2 for domestic yak, and 7.34/km2 for domestic sheep. A method based on meadows in the cold and warm seasons was used for estimating the densities and numbers of large wild herbivores and livestock, and was verified against records of livestock numbers. Population estimates for Kiang, Tibetan gazelle, blue sheep, domestic yak, and domestic sheep were 17,109, 15,961, 9324, 70,846, and 102,194, respectively. Based on published consumption estimates, the results suggest that domestic stock consume 4.5 times the amount of vegetation of large wild herbivores. Compared with traditional ground survey methods, performance of UAV remote sensing surveys of large wild herbivore populations was fast, economical and reliable, providing an effective future method for surveying wild animals.

Ungulates are essential for maintaining the health of grassland ecosystems on the Tibetan plateau. Increased livestock grazing has caused competition for food resources, threatening ungulates’ survival. The survival risk of food resources for ungulates can be quantified by the grazing pressure index, which requires accurate grassland carrying capacity. Previous research on the grazing pressure index has rarely taken into account the influence of wild ungulates, mainly due to the lack of precise spatial data on their quantity. In this study, we conducted field investigations to construct high-resolution spatial distributions for the four endemic ungulates on the Tibetan plateau. By factoring in the grazing consumption of these ungulates, we recalculated the grassland carrying capacity to obtain the grazing pressure index, which allowed us to assess the survival risks for each species. The results show: (1) Quantity estimates for Tibetan antelope (Pantholops hodgsonii), Tibetan wild donkey (Equus kiang), Tibetan gazelle (Procapra picticaudata), and wild yak (Bos mutus) of the Tibetan plateau are 24.57 × 104, 17.93 × 104, 7.16 × 104, and 1.88 × 104, respectively; they mainly distributed in the northern and western regions of the Tibetan plateau. (2) The grassland carrying capacity of the Tibetan plateau is 69.98 million sheep units, with ungulate grazing accounting for 5% of forage utilization. Alpine meadow and alpine steppe exhibit the highest grassland carrying capacity. (3) The grazing pressure index on the Tibetan plateau grasslands is 2.23, indicating a heightened grazing pressure in the southern and eastern regions. (4) The habitat survival risk analysis indicates that the high survival risk (the grazing pressure index exceeds 1.2) areas for the four ungulate species account for the following proportions of their total habitat areas: Tibetan wild donkeys (49.76%), Tibetan gazelles (47.00%), Tibetan antelopes (40.76%), and wild yaks (34.83%). These high-risk areas are primarily located within alpine meadow and temperate desert steppe. This study provides a quantitative assessment of survival risks for these four ungulate species on the Tibetan plateau grasslands and serves as a valuable reference for ungulate conservation and grassland ecosystem management.

Grazing pressure index considering both wildlife and livestock in Three-River Headwaters, Qinghai-Tibetan Plateau

Reference values were established for some serum hematological and biochemical constituents in Przewaiski’s and Tibetan gazelles in China. The contents of mineral elements in the blood, hair, liver, lung and muscle of Przewaiski’s and Tibetan gazelles were also measured. All values are reported for the first time for Przewaiski’s and Tibetan gazelles. Most hematological and serum biochemical values were similar to those of Tibet sheep, yaks, and camels, but the mean serum albumin concentration and the albumin/globulin ratio in Przewaiski’s and Tibetan gazelles were significantly higher than those in other ruminants and the mean thyroxine (T 4 ) concentration was half that in Tibet sheep. Liver contains the highest concentrations of copper (Cu), zinc (Zn), manganese (Mn) and iron (Fe). Hair contains higher amount of Sulphur (S). The concentrations of cobalt (Co), molybdenum (Mo), S and Mn from Przewaiski’s and Tibetan gazelles in the blood, hair, liver, lung and muscle were within the reference range for other ruminants. The concentration of selenium (Se) from Przewaiski’s gazelles in the blood and liver was significantly lower than that in Tibetan gazelles. Key words : Przewaiski’s gazelle, Tibetan gazelle, minerals, hematological values, biochemical constituents.

The extent to which a species responds to environmental changes is mediated not only by extrinsic processes such as time and space, but also by species-specific ecology. The Qinghai-Tibetan Plateau uplifted approximately 3000 m and experienced at least four major glaciations during the Pleistocene epoch in the Quaternary Period. Consequently, the area experienced concurrent changes in geomorphological structure and climate. Two species, the Tibetan antelope (Pantholops hodgsonii, chiru) and Tibetan gazelle (Procapra picticaudata), both are endemic on the Qinghai-Tibetan Plateau, where their habitats overlap, but have different migratory behaviors: the chiru is inclined to have female-biased dispersal with a breeding migration during the calving season; in contrast, Tibetan gazelles are year-round residents and never migrate distantly. By using coalescence methods we compared mitochondrial control region DNA sequences and variation at nine microsatellite loci in these two species. Coalescent simulations indicate that the chiru and Tibetan gazelle do not share concordant patterns in their genealogies. The non-migratory Tibetan gazelle, that is more vulnerable to the impact of drastic geographic changes such as the elevation of the plateau, glaciations and so on, appears to have a strong population genetic structure with complicated demographic history. Specifically, the Tibetan gazelle population appears to have experienced isolation and divergence with population fluctuations since the Middle Pleistocene (0.781 Ma). However, it showed continued decline since the Upper Pleistocene (0.126 Ma), which may be attributed to the irreversible impact of increased human activities on the plateau. In contrast, the migratory chiru appears to have simply experienced population expansion. With substantial gene flow among regional populations, this species shows no historical population isolation and divergence. Thus, this study adds to many empirical studies that show historical and contemporary extrinsic and intrinsic processes shape the recent evolutionary history and population genetic structure of species.

Tibetan Gazelle (Procapra picticaudata) are native wildlife to the Qinghai-Tibet Plateau, China. During the past five years, Tibetan Gazelle have been affected by rickets and osteomalacia, characterized by emaciation, growth retardation, lameness, enlargement of the costochondral junctions and abnormal curvature in long bones. The aim of the study was to determine possible relationships between the illness and mineral deficiency. The present result showed that phosphorus contents in soil and forage from affected pastures were significantly lower than those from healthy areas (P<0.01) and the ratio of calcium to phosphorus (Ca:P) in affected herbages was 13.16:1. Phosphorus contents of blood and hair from the affected animals were also significantly lower than those from healthy animals (P<0.01). Serum alkaline phosphatase values from affected Tibetan gazelles were significantly higher than those from healthy ones (P<0.01). Serum inorganic phosphorus contents of affected Tibetan gazelles were about half of those in healthy animals. Oral supplementation of disodium hydrogen phosphate in affected Tibetan gazelles successfully treated the illness. This study demonstrated that the ailment of the Tibetan gazelle was mainly caused by the phosphorus deficiency in forage.

Vigilance is an important antipredation technique that can be affected by many factors, such as body size and group size. Small animals are more vulnerable than large ones, so the former are expected to behave more vigilantly than the latter. This effect of body size on vigilance may occur inter- or intraspecifically. We studied the vigilance behavior of two sympatric wild ungulates, Tibetan antelopes (Pantholops hodgsonii) and Tibetan gazelles (Procapra picticaudata). Tibetan antelopes, with a body size of 33 kg are much larger than Tibetan gazelles, with a body size of approximately 14 kg. Tibetan antelopes are sexually and body-size dimorphic; that is, males are much heavier than females. Alternately, Tibetan gazelles are sexually dimorphic but the sexes do not differ in weight. Tibetan gazelles scanned their environment more frequently than Tibetan antelopes did. Small female Tibetan antelopes scanned their environment more frequently than males did, whereas male Tibetan gazelles scanned their environment more frequently than females did. Group size did not affect the vigilance of Tibetan gazelle, but its negative effect on the vigilance of male Tibetan antelopes was marginally significant. In female Tibetan antelopes, vigilance in large groups was high probably because of scramble competition and social monitoring. Our results suggested that body mass and group size play an important role in shaping the vigilance of these two rare Tibetan ungulates.

The carrying pressure of livestock is higher than that of large wild herbivores in Yellow River source area, China

Wild large herbivores are declining worldwide. Despite extensive use of exclosure experiments to investigate herbivore impacts, there is little consensus on the effects of wild large herbivores on ecosystem function.Of the ecosystem functions likely impacted, we reviewed the five most‐studied in exclosure experiments: ecosystem resilience/resistance to disturbance, nutrient cycling, carbon cycling, plant regeneration, and primary productivity.Experimental data on large wild herbivores' effects on ecosystem functions were predominately derived from temperate grasslands (50% grasslands, 75% temperate zones). Additionally, data were from experiments that may not be of adequate size (median size 400 m2despite excluding all experiments below 25 m2) or duration (median duration 6 years) to capture ecosystem‐scale responses to these low‐density and wide‐ranging taxa.Wild herbivore removal frequently impacted ecosystem functions; for example, net carbon uptake increased by three times in some instances. However, the magnitude and direction of effects, even within a single function, were highly variable.A focus on carbon cycling highlighted challenges in interpreting effects on a single function. While the effect of large herbivore exclusion on carbon cycling was slightly positive when its components (e.g. pools vs. fluxes of carbon) were aggregated, effects on individual components were variable and sometimes opposed.Given modern declines in large wild herbivores, it is critical to understand their effects on ecosystem function. However, this synthesis highlights strong variability in direction, magnitude, and modifiers of these effects. Some variation is likely due to disparity in what components are used to describe a given function. For example, for the carbon cycle we identified eight distinctly meaningful components, which are not easily combined yet are potentially misrepresentative of the larger cycle when considered alone. However, much of the observed difference in responses likely reflects real ecological variability across complex systems.To move towards a general predictive framework we must identify where variation in effect is due to methodological differences and where due to ecosystem context. Two critical steps forward are (a) additional quantitative synthetic analyses of large herbivores' effects on individual functions, and (b) improved, increased systematic exclosure research focusing on effects of large herbivores' exclusion on functions.A freePlain Language Summarycan be found within the Supporting Information of this article.

Grooming is an important behavioral defense against tick infestation for ungulates. The ‘programmed grooming model' explains the endogenous regulation of tick‐defense grooming and predicts different inter‐ and intra‐specific grooming patterns owing to the body size principle. Here, we studied the summer grooming behaviors of two sympatric Tibetan ungulates, to explore whether or not body size principle works inter‐ and intra‐specifically. The ungulates were sexually and body‐size dimorphic Tibetan antelopes (Pantholops hodgsonii) with body weight of c. 33 kg and sexually dimorphic but body‐size monomorphic Tibetan gazelle (Procapra picticaudata) with body weight of c. 14 kg. Group size was also included in our negative binominal regression model to determine whether or not the ungulates groomed more or less with the increasing group size. Results showed that large Tibetan antelopes groomed much less than small Tibetan gazelles inter‐specifically. Intra‐specifically, sex–age significantly affects the grooming rate of Tibetan antelopes. The largest adult males groomed the least, whereas the smallest fawns groomed the most. However, this sex–age effect is not found in Tibetan gazelle: males and females groomed similarly. These findings indicate that body size principle is fully supported inter‐ and intra‐specifically. Positive group size effect on grooming is observed in Tibetan gazelle, suggesting that released vigilance time from group size effect is probably transferred to grooming. From a conservation point of view, we suggest further studies on the testosterone effect on grooming patterns during the rut as well as on tick biology on the plateau.

There is an urgent need of understanding the distribution and abundance of the key species, Tibetan wild ass ( Equus kiang ), Tibetan gazelle ( Procapra picticaudata ) and Tibetan antelope ( Pantholops hodgsonii ) in the Three-River-Source National Park, especially after the first national park in China established there. We carried out field surveys in summers from 2014 to 2017 following the distance sampling protocol in the park, covering an area of 538000 km2. The total length of the survey routes is 14597.8 km. We recorded 3711 individuals of Tibetan wild ass, 1187 individuals of Tibetan gazelles, and 423 individuals of Tibetan antelopes. In order to accurately estimate the species abundance, we used species distribution models to quantify the relationship between species accurrences and 22 environmental variables, and predicted the population density in the whole study area. We compared the model prediction and field survey results, and made adjustment accordingly. The estimated abundance of Tibetan wild ass, Tibetan gazelle and Tibetan antelope in the study area is 44240, 13162, and 2390, respectively. To evaluate the potential bias of the estimation, we took into account of survey uncertainties, model uncertainties, and adjustment uncertainties using the detaction function based on distance sampling, R 2 of species distribution models, and spatial heterogeneity of model-observation matchness. Our new method for estimating species abundance is suitable for species whose distribution is well correlated with environmental varibles, and the results of distance sampling are available.

ABSTRACTUnderstanding the mechanisms of competition and coexistence among sympatric species is crucial for deepening our understanding of interspecific interactions and informing the conservation of rare and endangered wildlife. In this study, we utilized DNA macro‐barcoding technology to analyze the seasonal dietary habits of Kiang (Equus kiang) and Tibetan Gazelle (Procapra picticaudata) in Shiqu County, Sichuan Province, aiming to investigate their resource partitioning strategies and potential competition for limited forage resources. The results showed that Kiang mainly consumed Cyperaceae and Polygonaceae in both seasons, while Tibetan Gazelle fed on Polygonaceae and Rosaceae in the warm season and shifted to Ephedraceae in the cold season. Both species exhibited significant seasonal differences in dietary composition, with Tibetan Gazelle showing greater individual variation and seasonal shifts. In addition, their dietary niche was broader in the warm season, and overlap remained high, with indices of 0.89 and 0.87 in the warm and cold seasons, respectively. The results indicate that although Kiang and Tibetan Gazelle exhibit partial dietary overlap, they mitigate interspecific competition and achieve sympatric coexistence through differential use of dominant forage species, adjustments in dietary proportions, and individual dietary flexibility; notably, Tibetan gazelles exhibit stronger ecological adaptability. This study highlights a competition–coexistence dynamic along the trophic niche axis in typical plateau ungulates, providing insights for effective conservation strategies and biodiversity conservation in plateau regions.

Climate change impacts on high altitude wildlife distribution: Predicting range shifts for four ungulates in Changthang, eastern Ladakh

Ecological adaptation mechanisms of plateau ungulates to seasonal nomadic pastoralism on the eastern Qinghai-Tibetan plateau