# Food composition and food niche overlap of three kinds of canidae

> By following tracks in snow and sand to dens and latrines, researchers in China’s Inner Mongolia gathered over 300 scats from wolves, red foxes and raccoon dogs. Wolves were living largely on sheep, goats and cattle, red foxes on rodents, and raccoon dogs on birds and insects. Different diets, and raccoon dogs sleeping through the lean winter, may be how the three canids share a harsh grassland.

Summary by Kersey Lawrence, Original Wisdom. Updated 9 November 2026. Page: https://www.originalwisdom.com/tracking-literature/2009-zhang-liu-food-composition-food-niche/

## Citation and access

- **Authors:** Hong-Hai Zhang, Xin-Ping Liu, Hua-Shan Dou, Cheng-De Zhang and Ying Ren
- **Year published:** 2009
- **Journal or source:** Acta Ecologica Sinica
- **Full citation:** Zhang, H.-H., Liu, X.-P., Dou, H.-S., Zhang, C.-D. and Ren, Y. 2009. Food composition and food niche overlap of three kinds of canidae. Acta Ecologica Sinica 29(6): 347–350.
- **DOI:** 10.1016/j.chnaes.2009.09.015
- **Access status:** Publisher link only
- **Where to find it:** https://doi.org/10.1016/j.chnaes.2009.09.015

## Tags

- **Species:** Mammals > Grey wolf; Mammals > Raccoon dog; Mammals > Red fox
- **Region:** Asia > China
- **Tracking:** Scat; Snow tracks; Tracking; Tracks; Tracks and signs identification; Trailing
- **Behaviour and ecology:** Behaviour; Carnivore coexistence; Feeding; Interspecific competition; Intraguild interactions; Predation
- **Methods and technology:** Descriptive statistics
- **Data type:** New field data
- **Observer qualification:** Not reported
- **Discipline:** Behaviour and ecology; Wildlife tracking
- **Year published:** 2009

## Detailed keywords

- **Species:** Studied: wolf (Canis lupus), red fox (Vulpes vulpes) and raccoon dog (written in the paper as Nyctereutes ussurienusis Matschie). Food remains found in scats: horses, cattle, sheep and goats, hares, birds, small rodents, insects, plants, fishes, shrimps, mollusks and garbage (birds and small rodents were not identified to species). Avian eggshell remains were found near raccoon dog dens but not in their scats. Not found in wolf scats: wild ungulates such as Mongolian gazelle. The authors note that wolves sometimes preyed on red foxes.
- **Location and habitat:** Dalai Lake Natural Reserve (740,000 hm²), northeast Inner Mongolia, west of Hulunbuir, China (47°45′50″N to 49°20′20″N, 116°50′10″E to 118°10′10″E). Grassland with temperate continental climate, little rain and much wind; low mountains and hills, river plains and lowland near rivers and lakes; typical grassland, sand, saline meadow, swamp and meadow vegetation. Heavily grazed by livestock.
- **Topics:** diet analysis, scat analysis, food niche breadth, food niche overlap, competition and coexistence among canids, livestock predation, overgrazing, winter dormancy of raccoon dogs, comparison of frequency of occurrence and dry weight methods, hair and feather identification under the microscope.
- **Statistics or models:** frequency of occurrence and relative dry weight of remains; Spearman rank correlation (comparing the two methods); Shannon–Wiener index for food niche breadth; a food niche overlap index the paper calls the Pianka index (the formula printed, half the sum of absolute differences subtracted from one, is the one usually known as Schoener’s index); SPSS 13.0. Inconsistencies: (1) the food niche breadth values (wolf 1.0752, red fox 0.0744, raccoon dog 0.9103) cannot be reproduced from the frequencies in Tables 1 to 3 with the printed formula, and the red fox value looks far too low; the ranking (wolf widest, red fox narrowest) does match. (2) The overlap values can mostly be reproduced from the tables (wolf and raccoon dog 0.4049, red fox and raccoon dog 0.3777), but wolf and red fox comes out about 0.418 rather than the reported 0.4277. (3) The results text says raccoon dogs fed chiefly on birds and rodents with insects secondary, but by frequency insects (26.39%) came before rodents (22.69%); by dry weight rodents came second. (4) The methods sentence on telling raccoon dog scats apart names raccoon dogs twice, so it is unclear which species used fixed latrines. (5) The discussion says wolf and red fox feeding frequencies were “significantly different”, but no test of this is reported.
- **Data type:** New field data: scats collected August to October 2007 and March to July 2008 (59 wolf, 124 red fox and 134 raccoon dog samples).

## Synopsis

### 1. What they did

Wolves, red foxes and raccoon dogs share the grassland of eastern Inner Mongolia, China, and their dens and ranges overlap to some degree. The authors wanted to know what each species eats and how much their diets overlap, as basic information for protecting and managing them.

- Collecting scats. From August to October 2007 and March to July 2008, they followed tracks in snow and sand to find scats beside dens and along trails of footprints in Dalai Lake Natural Reserve. They told the three species apart by scat size (wolf scats are wider and longer) and by where the scats were left (raccoon dogs use fixed latrine sites). In all they collected 59 wolf, 124 red fox and 134 raccoon dog scats.

- Analysing the scats. Scats were oven-dried, then picked apart with tweezers and needles. Hair, feathers, bones, teeth, claws, insect pieces and seeds were separated and weighed. Hair and feathers were examined under a magnifying glass and microscope and compared with reference samples and a hair identification manual. Birds and small rodents were not identified to species.

- Measuring diet. For each species they calculated how often each food type turned up (frequency of occurrence) and its share of the dry weight of remains. They compared the two methods, and calculated how broad each diet was (food niche breadth) and how much each pair of diets overlapped (food niche overlap).

### 2. What they found

Wolves

- Livestock made up the bulk of the diet: sheep and goats (36.36% of occurrences, nearly half the dry weight), cattle (10.39%) and horses (3.90%), together 50.65%.

- Small rodents (23.38%), birds, hares, plants, insects and garbage made up the rest.

- No remains of wild hoofed animals such as Mongolian gazelle were found.

Red foxes

- Small rodents dominated (76.31% of occurrences, 84% of dry weight).

- They also ate plants, birds, fishes, sheep and goats, hares, insects, shrimps, cattle and garbage, each in small amounts. The authors think the livestock remains came from scavenging dead animals.

Raccoon dogs

- Birds were the most frequent food (39.81%), followed by insects (26.39%) and small rodents (22.69%).

- They also ate plants, fishes, shrimps and mollusks. Eggshell remains near their dens suggest they eat bird eggs too, though none were found in scats.

Diet breadth and overlap

- Wolves had the broadest diet, raccoon dogs the next broadest, and red foxes the narrowest.

- The diets of wolves and red foxes overlapped most (0.4277), then wolves and raccoon dogs (0.4049), then red foxes and raccoon dogs (0.3777).

Comparing methods

- The two methods ranked foods similarly for wolves and raccoon dogs, but not for red foxes, probably because foxes ate so many rodents that the other foods were eaten only now and then.

- Frequency of occurrence can overestimate small foods such as insects; dry weight is affected by how well each food is digested.

### 3. What they concluded

- The three canids share many food resources, so some competition occurs, but their diets also differ enough to reduce it.

- Wolves prefer large and medium-sized animals while red foxes mostly eat small ones, even though both eat small rodents.

- Red foxes concentrate on rodents while raccoon dogs rely more on birds, insects and plants, which matches findings from Europe.

- Raccoon dogs are dormant in winter when food is scarce, which avoids conflict with red foxes. This may explain how all three species coexist in a rather unproductive grassland.

- The authors suggest wolves eat livestock because wild hoofed animals such as Mongolian gazelle are endangered, because livestock numbers are high and overgrazing has squeezed the wolves’ living space, and because of how livestock are managed.

### 4. How tracking was or was not used

The researchers used “snowfield tracking and sandy land tracking” to collect scats: they followed tracks in snow and sand and gathered scats beside dens and along lines of footprints. They identified which species left each scat from its size and from where it was found (raccoon dogs use fixed latrines; scats were also found beside dens and with fresh signs). No further detail is given on how the trails were followed or how many scats might have been misidentified.

### 5. Tracker or observer certification

Not reported. Nothing is said about who followed the tracks or identified the scats in the field, although every result depends on scats being assigned to the right species. In the laboratory, the one person who identified the food remains was blind tested twice (on 60 and 50 samples), with 99.17% and 99.13% accuracy.

### 6. Other technologies, skills or innovations

- Hair scale impressions viewed under a 200 times microscope, and feathers measured under a 10 times magnifying glass, compared with local reference hair and a hair identification manual.

- Blind testing of the person identifying the food remains.

### 7. Implications for conservation (from the paper)

- Diet studies give basic information for evaluating habitat, estimating carrying capacity and managing carnivores.

- Wolves here depend heavily on livestock, which the authors link to the loss of wild hoofed animals such as the endangered Mongolian gazelle, to overgrazing and to the way livestock are managed.

### 8. Implications for tracking (Original Wisdom's observations)

_These are Original Wisdom's observations, not the authors'._

- The diet results for all three canids rest on telling their scats apart, yet the field identification, unlike the laboratory identification of food remains, was not tested. Following tracks to the scat, as was done here in snow and sand, is one way to link a scat to its maker; reporting how often this was possible would make such studies easier to judge.

## Cite this summary

Lawrence, K. 2026. Summary of: Food composition and food niche overlap of three kinds of canidae (Zhang and Liu et al., 2009). Original Wisdom, Tracking Literature. https://www.originalwisdom.com/tracking-literature/2009-zhang-liu-food-composition-food-niche/