Are stray Tibetan mastiffs a potential threat to snow leopards on the Tibetan Plateau?
(Poster)
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Around 2012, due to the rise then collapse of the Tibetan mastiff (Canis lupus familiaris) market, many dog breeders around Sanjiangyuan Nature Reserve abandoned their mastiffs. Since mastiffs have a range of biological traits and broad morphological adaptability, they occur at densities higher than any other similar sized native carnivores. In recent years, local people have observed incidents of mastiffs in packs attacking snow leopards (Panthera uncia) and other wildlife. As a result, stray mastiffs, acting as an introduced species, may become a novel threat to snow leopards, which are a flagship species of the fragile highland ecosystem.
Our research aims to understand the ecological role played by stray Tibetan mastiffs in the local ecosystem, and if mastiffs could act as potential predators, prey, and competitors for snow leopards.
We assessed stray mastiff population dynamics by photo recaptures and line transects around 57 sites across 3 years. We put GPS collars on 16 stray mastiffs to estimate their home range, distribution patterns, and movement model. We collected 386 snow leopards and 157 mastiffs scat samples to acquire diet and intestinal microbial community. We set 55 camera traps to analyze activity patterns and habitat selection of them. We then looked at how stray Tibetan mastiffs were interacting with snow leopards through spatial, temporal, and resource separation within Sanjiangyuan Nature Reserve.
Pregnancy rate of female mastiffs was as high as 40.4±5.0%, with the death rate of pups estimated at 64.1±7.3% in the first year, the population growth rate was 5.1±3%. The density of stray Tibetan mastiffs ranged from 0.34-10.6 Indi/km2, averaged at 1.6±0.3 Indi/km2. 95% kernel estimation of home range ranged from 0.15-28.23 km2, average 10.14±3.50 km2. High birth rate and density, large home range, combined average weight exceeds 20 kg and group hunting behavior, the stray Tibetan mastiffs may be in a dominant position in the interference competition.
The dietary overlap between Tibetan mastiffs and snow leopards was 0.43, ANOSIM (OTU level) of intestinal microbial community was 0.33. This suggests that there are similarities in dietary structure among both species. Around 52962 km2 is occupied by Tibetan mastiffs, and 19756km2 was in snow leopard habitat (16.9%). Combining the overlap of activity patterns was 0.53, we cannot neglect the exploitative competition between the two species.
All the evidence demonstrates stray Tibetan mastiffs could potentially become an emerging threat to snow leopards. Our research can contribute valuable knowledge on a key threat to snow leopards and develop locally relevant solutions that is scientifically based, locally accepted and participatory. We have been working with the local government and communities on the early tests of public education, sterilization and adoption of stray mastiffs. As a result, we hope to see a better future for the long-term conservation of Sanjiangyuan Region.