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How do you save a species when you don’t know what it eats?
With so many of the small wild cats, there was virtually nothing known of their natural history until recently. Questions like what kind of habitat do they need, what threats do they they face and even what was in their diet needed to be answered before any conservation programs could be planned.
One small cat that we knew very little about was the Pallas’s Cat Octocolobus manul from the grassland steppes of Asia. Researchers from the University of Bristol in the UK are slowly beginning to unravel their mysteries.
Dietary specialization is one of the factors contributing to the vulnerability of a species. Generalist feeders like the bobcat are adaptable, and change their diet to reflect whatever prey species are most abundant at any given time. Specialist feeders like the Iberian lynx, who are dependent upon one prey species, suffer serious consequences when their prey base disappears.
The objectives of the Pallas’s cat study were to investigate the dietary composition and prey selection of the cats, who were suspected to be generalist feeders. Researchers set out to quantify seasonal variation in the diet and prey consumption, and sought to understand the effect of disturbances to the cats’ prey base.
The diet of the Pallas’s cat was assessed by scat analyses, and prey surveys were used to estimate availability. Analysis of 146 scats identified 249 prey items.
Pallas’s cats in the study area ate a broad range of small mammals (85%), insects, birds, reptiles and carrion, but Daurian pikas were the most frequently consumed prey. Pikas are 2-4 times larger than other small mammals found in their diet, and were selected regardless of the high availability of other prey species. This behaviour indicates a specialist feeding habit.
Only 2 small mammal species, Siberian jerboas and Russian dwarf hampsters, were not eaten; both are nocturnal. Observed activity peaks of Pallas’s cats suggest they are crepuscular (hunting dawn and dusk) or active throughout the day.
Seasonal differences in their diet included a winter increase in insect consumption and a decrease in pika consumption. Because insects were either dead or dormant in subzero conditions, their increased use was not due to chance encounters. Pallas’s cats were actively seeking insects and able to locate caches of frozen grasshoppers or the hibernation sites of beetles.
The reduced consumption of pika during the winter could be explained by a decrease in their availability. Although differences in pika numbers were not detected between seasons, inclement weather and use of underground food stores decreased the amount of time they spent on the surface.
Despite a 7 fold increase in rodent density during the summer, Pallas’s cats continued to select pikas, and did not prey on more abundant species.
Although accurate information is difficult to obtain, small mammal poisoning campaigns continue on the steppes of central Asia. Pikas and rodents have been targeted as pests by poisoning campaigns in China, Mongolia and Russia because they are believed to compete with livestock for forage, and are supposed to serve as vectors for the plague. In China, some pika populations were reduced to less than 5% of their precontrol numbers.
Declines in local Pallas’s cat populations will likely go unrecorded because they already live at low population densities and are difficult to survey. Further work is needed to quantify the impact of small mammal control programs on Pallas’s cats and other carnivores in the area.
Citation: Journal of Mammology 91(4): 811-817, 2010
Dietary composition, plasticity and prey selection of Pallas’s cats. Steven Ross, Bariushaa Munkhtsog and Stephen Harris
School of Biological Sciences, University of Bristol, United Kingdom. Institute of Biological Sciences, Mongolian Academy of Sciences, Mongolia