| Helan Mountain has a more pronounced "ecological island" effect due to its distinct habitat and geographic position,and there is no significant wild animal population migration.Due to the "intermediate predator effect," the red fox(Vulpes vulpes),whose ecological niche is stable and population is growing annually,has emerged as the most prevalent and numerous main intermediate predator in the Helan Mountains area.Feral dogs(Canis familaris),which have a large population and are becoming more active,have moved into the Helan Mountains over the past ten years as a result of the relocation of residents and mines.After a long period of survival in the mountains,they have adapted to the local environment,formed a sizable population,and changed into a new intermediate predator in the Helan Mountains.We used the sample line method,infrared camera method,nuclear density estimation method,and fecal DNA macro barcoding technique to examine the activity rhythm and feeding habits of red fox and feral dogs in the Helan Mountains from 2021 to 2022 in order to examine the ecological impact of feral dogs,which are also Canidae,as an invasive species on the red fox.A total of 39 transects were surveyed,including 16 in Inner Mongolia and 23 in Ningxia’s Helan Mountain National Natural Reserve,whose combined lengths reach 233.582 km and153.305 km,respectively.The infrared camera captured 12 660 images of wildlife throughout its 19 710 effective working days,including 203 red foxes and 149 feral dogs.The two species were compared,and the main findings were as follows:1.A total of 320 effective independent events were recorded in red foxes,including 169 in the warm season(April 11-October 10)and 151 in the cold season(October 11-April 10).Among them,there were 62 warm season daytime(07:00-18:59)and 107 warm season night(19:00-06:59),with a nocturnal index of β = 0.63;67 during the day in the cold season and 84 night in the cold season,with a nocturnal index of β = 0.56,indicating that the red fox belongs to a nocturnal animal.A total of 206 effective independent incidents of feral dogs were recorded,including 89 in the warm season and 117 in the cold season.Among them,there were45 days in the warm season and 44 nights in the warm season,with a nocturnal index of β =0.49;68 during the day in the cold season and 49 nights in the cold season,with a nocturnal index of β = 0.41,indicating that feral dogs belong to diurnal animals.2.According to the findings of the kernel density estimation method,the red fox reached its greatest daily activity at 22:00 in the cold season after having a considerable activity peak at2:00 in the warm season.In the warm season,feral dogs experience a significant activity peak at 19:00 and reach their highest daily activity at 11:00,while in the cold season,they experience a significant activity peak at 17:00 and reach their peak daily activity at 8:00.The activity rhythm overlap coefficient results showed that the activity overlap coefficient of red fox and feral dog in the warm season was ? = 0.29(95% CI: 0.23-0.44),which was mild overlap,and the activity overlap coefficient of red fox and feral dog in the cold season was ? =0.44(95% CI: 0.37-0.59),which was mild to moderate overlap.3.The species fed by red foxes in the Helan Mountains area include 138 generas in 53 orders,88 families,Ziziphus of Rhamnaceae,Vitis of Vitaceae,Juniperus of Cupressaceae,Rosa of Rosaceae and Artemisia of Asteraceae are the main plant-eating foods,accounting for70.51%.Phasianus of Phasianidae and Pseudois of Bovidae are the main animal foods,accounting for 83.54%.The feral dogs in the Helan Mountain area feed on 90 generas in 42 orders,53 families,Artemisia of Asteraceae,Prunus of Rosaceae and Oryza of Poaceae as the plants that feed more,accounting for 40.89%.Gallus of Phasianidae,Pseudois of Bovidae and Anas of Anatidae are the main animal species that feral dogs feed,accounting for 85.43%.4.There were no significant differences in the diversity of plant-eating food composition in red foxes and feral dogs,Chao1 and Shannon indices,and the breadth of plant-eating food niche was lower in red fox(2.8000 ± 1.6260)than that of feral dogs(2.9697 ± 1.1733)but there was no significant difference,and the value of Schoener food overlap index was 0.664.There was no significant difference in the diversity Chao1 index of animal food composition between red foxes and feral dogs,there was a significant difference in the Shannon index(p =0.006),the red fox(1.9755 ± 0.7763)was lower in the animal food niche width than that of feral dogs(2.2885 ± 0.9140)but there was no significant difference,and the value of Schoener food overlap index was 0.748. |
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