An account of badger diet in an arid steppe region of Mongolia

1. What they did

Badgers range widely across Europe and Asia, but most studies of their diet come from European areas with mild climates, high rainfall and farmland. Few have looked at the colder, drier and less disturbed lands of northern Asia. This short communication describes what Asian badgers eat in the Ikh Nart Nature Reserve, an arid steppe and semi-desert reserve in central Mongolia with no agriculture, where badgers hibernate from about November to April.

• Collecting scats. From 15 May to 15 September in 2006 and 2007, the authors collected fresh scats (under a week old) as they came across them. Scats were identified by comparison with reference scats from badgers live-trapped for another radio-telemetry study. To reduce the risk of misidentification, they also collected scats at badger latrines and near the den entrances of five known badgers.
• Analysing them. They soaked the dried scats in water and strained them through nylon mesh, identified the larger remains to species where possible using reference collections, and measured their volume with graduated cylinders. They checked the fine sediment under a microscope for earthworm bristles (chaetae) and gizzard rings.
• Measuring diet. For each food item they calculated the percentage of scats in which it occurred and its percentage of total scat volume.

2. What they found

• They analysed 116 scats, containing insects, mammals, birds, reptiles, plant material and human garbage (food wrappers, plastic and fabric).
• Insects were by far the main food: in 96.6% of scats and 79.3% of the volume. The authors identified 28 insect species. Grasshoppers (Acrididae) were in 72.4% of scats and made up 56% of the volume; beetles were in 64.7% of scats, and cockroaches in 45.7%.
• Everything else each occurred in under 34% of scats, and together made up only about 21% of the volume:
• Plant material: 33.6% of scats but only 3.6% of volume, including leaves, stalks, and fruits and seeds of Gobi apricot and Nitraria sibirica shrubs. Most seeds were whole and intact.
• Mammals: 22.4% of scats, 8.6% of volume, mainly rodents, with a few remains of pika, hedgehog and livestock.
• Reptiles: 19.0% of scats, 4.6% of volume, all toad-headed agama lizards, the most common lizard in the reserve.
• Birds: 6.0% of scats, mostly bones and small feathers, and egg fragments in one scat.
• Garbage: 5.2% of scats, 3.3% of volume.
• No earthworms: no earthworm chaetae or gizzard rings were found in any scat.

3. What they concluded

• Badgers in Ikh Nart ate mainly insects and occasionally other foods, but not earthworms. Insects, especially grasshoppers, were very abundant in summer and autumn, which may explain how often they appeared. This matches other studies from arid parts of the former Soviet Union.
• Earthworms are a key food for badgers in parts of the UK, continental Europe and Japan, where badgers have even been called earthworm specialists. The authors suspect earthworms are rare or absent in Ikh Nart because of the cold climate, sandy and gravelly soils, and little leaf litter, and conclude that earthworms are not an important food for badgers in Mongolia’s arid regions.
• Rodents and lizards were eaten in line with their low or moderate abundance. Birds were rarely eaten despite at least 110 species in the reserve, perhaps because birds are harder to catch during the cold night hours when badgers are most active.
• Fruits ripen in late autumn or early winter, when badgers are mostly inactive, which may explain why they were rare in scats. Because most seeds passed through whole, badgers may help disperse some plants.
• Garbage was rare; the only sources are herders’ ger (yurt) sites, usually guarded by large dogs, which probably keep badgers away.
• Overall, the diet suggests badgers forage opportunistically, eating what is abundant and available. Studies comparing food abundance with diet are needed to examine their food preferences and foraging strategy.

4. How tracking was or was not used

The study rests on finding and identifying badger scats in the field. Scats were identified by comparing them with reference scats from live-trapped badgers, and some were collected at badger latrines and near the den entrances of known badgers to reduce misidentification. Only fresh scats (under a week old) were collected, which required judging scat age. No trailing or other tracks were reported.

5. Tracker or observer certification

Not reported. The paper does not say who found and identified the scats or how their identifications were checked, beyond the use of reference scats and known latrines and dens. T. Munkhzul and N. Javzmaa are thanked for help identifying food remains.