4. Discussion

In our study, two previously overlooked yet critical threats to cat survival were identified in the Gyatong Grassland: killing by free-ranging dogs and genetic contamination from domestic cats, which supplements our previous understanding of the major threats of pika poisoning programmes and illegal hunting (Sanderson et al. , 2010).

4.1 Killing by free-ranging dogs

We understand that solely based on the results from interviews and camera trap monitoring, we cannot prove that free-ranging dogs killed both cats – after all, the scene of killing was neither recorded nor seen by anyone. However, combined with other evidence from previous research as well as our observations of dogs’ predation on other sympatric wildlife in the region, we do believe that free-ranging dogs have been the killers.
Liu’s study (2020) in the Sanjiangyuan Region revealed that stray dogs showed fairly large home ranges (10 km2 on average), large body weight (over 20 kg), and a high hunting success rate brought by group-hunting strategies, which indicated that they might be in a dominant position in their relationships with sympatric meso-carnivores. Meanwhile, stray dogs are notoriously known to harass sympatric wildlife and finally resulting in an reduction of survival rate via direct killing or increased stress level, altered activity pattern and habitat use (Lenth, Knight, & Brennan, 2008; Gingold et al. , 2009; Younget al. , 2011; Hughes & Macdonald 2013). For example, in New Zealand just one stray dog killed about 500 kiwis (Apteryx australis ) in six weeks, accounting for more than half of local kiwi population (Taborsky, 1988). This is particularly worrying in the context of the recent surge in stray dog population in the Tibetan region. The collapse of the Tibetan mastiff market along with the implementation of nomadic settlement projects has resulted in a dramatic decrease in the economic and productive value of domestic dogs, leading to widespread dog abandonment in the region (Jenny, 2012). Official statistics from 2016 show that there were more than fifty thousand dogs in Golog Prefecture alone, Qinghai province, of which fourteen thousand were stray dogs (Yin et al. , 2017). The spots of these dogs’ predation on wildlife have been frequently made (Fig. 4a, b; Yanget al. , 2019). Besides the fairly high population density (4.6 individual / km2 near villages), the growth rate of them (10.3% on average) also indicates that this issue requires more attention and efforts (Liu, 2020).
In the case of Gyatong, our interviews revealed a fact that the current rearing methods of locals blurred the boundary between domestic dogs and stray dogs. At night or during the absence of owners, these domestic dogs would be unchained and allowed to hunt for themselves (Messerschmidt, 1983; Cui, 2006). As a natural result, such potential overlap in both time and space between free-ranging dogs and nocturnal Chinese mountain cats (Liao, 1988) has facilitated interactions detrimental to the cat. Moreover, cats are not the only victims in the region, with other meso-carnivores (e.g., Asian badgers Meles leucurus , Tibetan foxes) all threatened by these dogs. In June 2019, during the absence of the owner of a house 150 m away from the den of the Chinese mountain cat family, his two dogs were found to kill at least two Tibetan foxes, one steppe polecat (Mustela eversmanii ), four Asian badgers, and one Himalayan marmot (Marmota himalayana ) (Fig. 4b, Fig. 6; all these carcasses were found near the house and probably there were more undiscovered). Badgers and marmots were all consumed by dogs, but carnivores such as foxes and polecats were only killed and left intact, in accordance with previous diet analyses (Liu, 2020). Consequently, this leads to an increased exposure of the cats to free ranging dogs, because when dogs are attracted to the dens of badgers and marmots, the cats might be using them as hiding burrows (Sanderson et al. , 2010; Han et al. , 2020; Fig. 4c).

4.2 Genetic contamination by domestic cats

Compared with threats from free-ranging dogs, genetic contamination from domestic cats revealed by our genetic analysis is a much more imperceptible threat, but with a long-lasting impact on the survival of the cat as a unique lineage.
Despite the maintenance of typical morphological (Fig. 1a) and ecological features, our two Chinese mountain cat specimens carried both mitochondrial and nuclear genotype of domestic cats. This is the first time that wild individuals of the Chinese mountain cat were proven to contain the DNA of their domestic relatives. On the flip side, genetic introgression from the Chinese mountain cat to sympatric domestic cats has been proven with genetic evidence and supported by local observations. Yu et al. (2021) found that domestic cats sampled from the core range of the Chinese mountain cat’s distribution (i.e., eastern Qinghai and northwestern Sichuan) carried 5-10% genetic admixture from Chinese mountain cats, which dated back to around 7.4 generations ago (approximately 20 years). Comparatively, our case samples from two hybrid cubs showed approximately 30% genetic source from Chinese mountain cat, suggesting a more recent admixture event or higher local introgression background. The hybrids also displayed intermediate morphological characters, e.g., light brown fur, little ear tufts, light brown pupils (Fig. 5b). Our finding supported that long-term bidirectional gene introgression between Chinese mountain cats and local domestic cats existed in the Gyatong Grassland and adjacent regions.
Moreover, local herdsmen claimed that the cats were rather common around their village about ten years ago, the time when many domestic cats were kept as pets. During mating seasons in spring, they could hear the cat screaming for the whole night, and a few locals have even seen male Chinese mountain cats wandering into their village to fight male domestic cats and mate with females (the opposite was not learned during this survey). Such potential asymmetric hybridization is probably related to the larger body size of the Chinese mountain cats compared to domestic cats, which gives them a mating advantage in accessing females (Similar phenomena of male Chinese mountain cats mating with the smaller female Asiatic wildcats F. s. ornate have also been reported; Yuet al. , 2021). Furthermore, from camera trap monitoring, we know that the male kitten has survived. On March 2019, he was found urine marking a boulder located below the third den of the breeding family, right after a white domestic cat did so, which suggested the opportunity for their mating competition.
The bidirectional gene flow between the Chinese mountain cat and local domestic cats in the Sanjiangyuan Region, if confirmed by future genetic analysis on larger scale, could be quite detrimental to the vulnerable Chinese mountain cat species, jeopardizing its distinctiveness, genetic integrity, and even its survival in the alpine environment. Extensive studies have demonstrated a similar genetic contamination crisis faced by the European wildcat (F. s. silvestris ), which commonly interbreeds with the ubiquitous feral cats, raising widespread conservation attention (Allendorf et al. , 2001; Oliveira et al. , 2008). For Chinese mountain cats, more research efforts are in urgent need to investigate the extent of the problem.

4.3 Tricky balance among humans, dogs, cats and beyond

Both cats were genetically contaminated by domestic cats and very likely, killed by free-ranging dogs, which are almost inevitable results from their proximity to human settlements (Webb et al. , 2016). Among all the three dens of the family, the last one was located less than 100 meters away from a herdsman’s house who owns one cat and three dogs. Such proximity facilitates frequent contact of the Chinese mountain cats with free-ranging dogs and domestic cats. Apparently, there requires no further words to explain the legitimacy of all of their existences. However, this fact indeed constitutes the very bedrock when we are trying to find a way out of this dilemma.
The complexity of the issue is rooted in both the material as well as the spiritual life of the Tibetans. On the one hand, domestic dogs and associate rearing methods are of utter importance to the safety of property and life of local herdsmen. Currently, in the Sanjiangyuan Region and most areas on the Tibetan Plateau, wolves and bears are two carnivores that have caused most human-wildlife conflicts (Dai et al. , 2020). As the major ‘weapon’ against them, unchained dogs, particularly Tibetan mastiffs, are of unparalleled importance to local herdsmen (Messerschmidt, 1983). On the other hand, the locals seem to acquiesce in the killing behaviors of their dogs. Our interview suggested that many of the locals were unaware of the dog’s negative impact on wildlife. Despite so, from the fact that most local herdsmen would set their dogs free when they are leaving, it is clear that they are allowing dogs to prey on wildlife. In this case, the real causes of such avoidable incidents were selectively attributed to the poor and inevitable fates of the victim animals, instead of the indifference (or ‘bad karma’ if more precisely) of the dog owners (note that by no means we are criticizing Tibetan Buddhism here because it was the exact reason that has kept the Tibetan Plateau one of the most pristine habitats to wildlife in the world, as shown in Ma & Chen, 2005; Shen et al. , 2012; Li et al. , 2014).
Therefore, it was not realistic to simply ask nomads to chain their domestic dogs all the time. Leaving dogs to neighbors seems worth trying if the causal connections could be established between ‘setting dog free’ and ‘deaths of innocent wild animals’, yet which might be most effectively done by someone with same religion. Comparatively, for stray dogs, potential management measures seem less tricky and more feasible. According to the interview conducted in Gyatong, most local herdsmen did not mind the treatments of stray dogs (e.g., neutering, killing) as long as they are not treated on-site (“you can put them in a truck and take them away, but do not tell me what you will do to them”). The only difficult part of this solution is that surrounding Tibetan monasteries must be well informed and educated, since during our survey they were found feeding and harboring stray dogs to a great extent (for example, a Nunnery in the study area have been keeping over one hundred stray dogs and none of them was chained).
Consequently, it now seems to us the most feasible solutions to mitigate the situation in Gyatong are, (1) carefully monitoring and regularly catching stray dogs in the region, (2) persuading dog owners send their dogs to a host family instead of setting them free when they are away, (3) establishing the causal link between ‘dead wild animals’ and ‘dogs owners’ misdeeds’ in the mindsets of the locals. For dog-release at night, it seems to us there is no feasible alternative for now, unless the current conflicts between humans, bears and wolves are alleviated. However, as stated above, suggestions as such might also be applicable to the region alone, considering the very high yet often overlooked cultural biodiversity within the Tibetan Plateau (e.g., studies conducted in the Golog Prefecture suggested that the locals show no tolerance to any dog-hurting behavior; Liu, 2020).
To summarize, through the examination and analysis on two carcasses from a consistently monitored Chinese mountain cat family and two hybrids, as well as the survey on free-ranging dogs in this area, we suggest that two so-far overlooked threats to the cat are elicited from domestic dogs and cats, their foes and their kins, in addition to the previously-identified threats of pika poisoning programs and illegal hunting. With the synthesis on available knowledge and observations, the complexity of the issue was illustrated and accordingly, potential solutions were proposed. With the species up-listed to the National First-Class Protected Wild Animal, more attention should be paid to the Chinese mountain cat. Along with it, we hope more research and conservation resources and efforts will be directed to this endemic carnivore.