# Variation of Insect Assemblages in Fox and Marten Faeces Collected in Southern Poland

> What can a beetle leg in a scat tell a tracker? Picking through fox and marten scats from two Polish national parks, researchers identified 30 kinds of insects and other small creatures. Martens left signs of raiding insect nests and hunting small beetles in meadows, while foxes ate bigger forest beetles and carrion insects that point to scavenging.

Summary by Kersey Lawrence, Original Wisdom. Updated 9 November 2026. Page: https://www.originalwisdom.com/tracking-literature/2008-skalski-wierzbowska-variation-insect-assemblages-fox/

## Citation and access

- **Authors:** Tomasz Skalski and Izabela Wierzbowska
- **Year published:** 2008
- **Journal or source:** Annales Zoologici Fennici
- **Full citation:** Skalski, T. and Wierzbowska, I. 2008. Variation of insect assemblages in fox and marten faeces collected in southern Poland. Annales Zoologici Fennici 45(4): 308–316.
- **DOI:** 10.5735/086.045.0411
- **Access status:** Hosted (freely available elsewhere)
- **PDF:** https://www.originalwisdom.com/wp-content/uploads/2026/11/2008_Skalski_and_Wierzbowska_variation-of-insect-assemblages-in-fox-and-marten-faeces.pdf

## Tags

- **Species:** Mammals > Pine marten; Mammals > Red fox; Mammals > Stone marten
- **Region:** Europe > Poland
- **Tracking:** Scat; Sign surveys; Tracking; Tracks and signs identification
- **Behaviour and ecology:** Behaviour; Carnivore coexistence; Feeding; Habitat selection; Scavenging
- **Methods and technology:** Bootstrapping
- **Data type:** New field data
- **Observer qualification:** Not reported
- **Discipline:** Behaviour and ecology; Wildlife tracking
- **Year published:** 2008

## Detailed keywords

- **Species:** Studied: red fox (Vulpes vulpes), pine marten (Martes martes) and stone or beech marten (Martes foina). The two martens could not be told apart by their scats, so their scats were pooled as “marten spp.” Food remains found in the scats (30 taxa, mainly beetles and wasps): ground beetles including Abax parallelepipedus, Amara sp., Carabus auronitens, C. cancelatus, C. coriaceus, C. glabratus, C. linnei, C. violaceus, Cychrus caraboides, C. attenuatus, Poecilus versicolor, Pseudoophonus rufipes, Pterostichus burmeisteri, P. melanarius and P. niger; dung beetles Aphodius sphacelatus and Geotrupes stercorosus; carrion beetles Silpha atrata and Necrophorus sp.; Byrrhus sp., Melasoma sp., Otiorhynchus ovatus, Otiorhynchus sp. and Selatosomus aeneus; European earwig (Forficula auricularia, written “auriculata” in the paper); bumblebee (Bombus sp.); European hornet (Vespa crabro); grasshoppers or crickets (Orthoptera); a spider (Araneus sp.) and a millipede (Julus sp.). Table 1 spells some names differently: “Cychrus craboides”, “Pterostichus brumeisteri” and “Forficula auriculata”; the usual spellings are used here.
- **Location and habitat:** Southern Poland. Ojców National Park (ONP; 50°12′N, 19°46′E): a small deciduous forest complex of about 1528 ha of patchy woods surrounded by semi-natural and human-made habitats. Gorce National Park (GNP; 49°32′N, 20°06′E): a large beech and spruce forest complex (6585 ha) with small patches of semi-natural meadows. Scats were collected along forestry roads.
- **Topics:** scat (faecal) analysis; diet of sympatric carnivores; insects and other invertebrates as a supplementary food; insects as bioindicators of where a predator fed; meadow versus forest foraging; nest-building insects; carrion insects as a sign of scavenging; prey size selection; niche breadth and niche separation; coexistence of fox and martens.
- **Statistics or models:** Bootstrap estimator of species richness and a rarefaction curve (EstimateS 8.0); body mass of beetles estimated from body length (formula from Jarosik 1989); canonical correspondence analysis (CCA) and redundancy analysis (RDA) in CANOCO 4.5 with Monte Carlo permutation tests; log(n + 1) transformation; Shannon-Wiener niche breadth index compared with a t-test; regression of carabid abundance in scats against their relative abundance in the forest community (exponential curve for martens, straight line for foxes); F tests on beetle size classes. Inconsistencies and gaps: (1) the abstract says thirty insect species, but the Results say 30 arthropod species, and Table 1 includes a spider and a millipede; (2) the number of scats in each predator and park group is not given, and some frequencies and abundances in Table 1 do not fit one sample size (for example, in martens in GNP, frequencies of 0.17 with only one specimen, alongside a frequency of 0.08); (3) the CCA axes are reported as significant only at p < 0.1 (Table 2), and the fourth CCA eigenvalue (4.438) is larger than the first, which is unusual and may be a typing error; (4) the text places the hornet in the fox and meadow group, while in Figure 2 it sits on the marten side; (5) the Methods do not say how the forest ground beetle community used in Figure 5 was sampled, and Figure 5 shows Ojców National Park only.
- **Data type:** New field data: scats collected in 2003 and 2004, along transects walked twice a month. 200 scats were collected in Ojców and 150 in Gorce, and 45 were chosen at random for this analysis.

## Synopsis

### 1. What they did

Red foxes and martens often live side by side and eat much the same food. Insects turn up often in their scats, but most diet studies lump them together as an “unrecognisable” fraction. Because many insects live only in particular habitats (meadow or forest, for example), the authors asked whether the insects in a carnivore’s scats could show not only what they eat but also where they feed, and how fox and martens differ.

- Collecting scats. In 2003 and 2004 they walked transects along forestry roads in two national parks in southern Poland, twice a month, and collected only fresh scats of red foxes and martens: 200 in Ojców National Park and 150 in Gorce National Park. Pine and stone martens are both common there, and their scats cannot be told apart by how they look, so all marten scats were recorded as “marten”.

- Choosing the sample. To avoid a few individual animals dominating the results, they picked 45 scats at random for analysis.

- Sorting the remains. Scats were frozen, washed through a fine sieve (0.5–1 mm mesh) and sorted into food categories. Insect and other arthropod remains were identified to species using reference collections from each park, and individuals were counted from parts such as heads, the shield behind the head (pronotum), and legs.

- Analysing them. They estimated how many species they might expect to find, grouped the insects by their ecology (meadow, forest, nest-building, carrion feeding and so on), and used ordination methods to see what best explained the differences between scats. They also compared diet breadth, beetle sizes, and how closely the beetles in scats matched the beetles living in the forest.

### 2. What they found

Insects in the scats

- They identified 30 species of arthropods, mainly beetles and wasps. The species curve was close to levelling off, suggesting most of the species expected in the area had been found.

- Ground beetles of the genera Carabus and Pterostichus were the most often found.

- Earwigs, a nest-building insect, turned up in a quarter of the marten scats from Ojców (39 earwigs in all), and always in large numbers.

What separates fox from marten

- Which predator left the scat (fox or marten) explained most of the variation in the insects found, more than which park it came from.

- Foxes ate more forest insects, larger insects, and carrion feeders such as the carrion beetle Silpha atrata, which the authors take as a sign that foxes eat decaying meat more often.

- Martens ate more meadow insects and nest-building insects, such as earwigs, bumblebees and large grasshoppers or crickets, and smaller insects overall.

- Insects were more abundant and varied in the scats from Ojców.

Diet breadth and choice

- Foxes had a broader insect diet than martens.

- The ground beetles in marten scats closely matched how common each beetle was in the forest. The beetles in fox scats did not. The authors read this as martens eating beetles as they come across them, while foxes pick certain species, not necessarily the most common ones.

- Comparing three beetle size classes (5–15, 15–25 and 25–35 mm), foxes ate significantly more large ground beetles and martens significantly more small ones.

### 3. What they concluded

- Identifying insects to species in scats is a useful tool for learning about a carnivore’s diet and the habitats where they feed.

- Even a small part of the diet, which some authors consider unimportant, can reveal differences between predators that share an area.

- Fox and martens show clear differences in the insects they eat: martens probably search for insect nests, a rich food source, while foxes choose larger beetles.

- The carrion insects in fox scats point to scavenging, although the authors note there is no method to separate scavenging from hunting, even from stomach contents.

- Few insect species were eaten equally by both predators, which supports the idea that the two differ in their feeding niches.

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

The study rests on finding and identifying scats. Fresh scats were collected along transects on forestry roads, and each was assigned to red fox or marten. The paper does not say how fox and marten scats were told apart, but notes that pine and stone marten scats cannot be separated by visible features, so they were pooled. No trailing or other tracks and signs were used.

### 5. Tracker or observer certification

Not reported. The paper does not say who identified the scats or how. Barbara Bober-Sowa is thanked for collecting some of the material. Because every result depends on which predator left each scat, the reliability of scat identification matters to the findings.

### 6. Other technologies, skills or innovations

- Identifying insects to species from fragments in scats, using reference insect collections from each park.

- Estimating beetle body mass from body length.

- Using the ecology of the insects eaten (meadow, forest, nest-building, carrion feeding) as clues to where and how the predator fed.

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

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

- A scat holds more than the predator’s meal: the insects inside can hint at the habitat where an animal fed and whether they visited carrion or insect nests.

- The paper shows a common limit of scat studies: pine and stone marten scats could not be told apart, and how fox and marten scats were separated is not described. Confirming scat identity (for example by DNA, or by tracks at the scat) would strengthen this kind of study.

## Cite this summary

Lawrence, K. 2026. Summary of: Variation of Insect Assemblages in Fox and Marten Faeces Collected in Southern Poland (Skalski and Wierzbowska, 2008). Original Wisdom, Tracking Literature. https://www.originalwisdom.com/tracking-literature/2008-skalski-wierzbowska-variation-insect-assemblages-fox/