# Histological, chemical and behavioural evidence of pedal communication in brown bears

> Brown bears may leave messages with every step. Researchers found scent glands between the toes and on the soles of bear paws, scent chemicals found only in adult males, and a camera recorded bears twisting their feet into a trail of worn footprints by a rubbing tree, mostly males in the mating season. The tracks themselves seem to be a way for solitary bears to talk to each other.

Summary by Kersey Lawrence, Original Wisdom. Updated 9 November 2026. Page: https://www.originalwisdom.com/tracking-literature/2017-sergiel-naves-histological-chemical-behavioural-evidence/

## Citation and access

- **Authors:** Agnieszka Sergiel, Javier Naves, Piotr Kujawski, Robert Maślak, Ewa Serwa, Damián Ramos, Alberto Fernández-Gil, Eloy Revilla, Tomasz Zwijacz-Kozica, Filip Zięba, Johanna Painer and Nuria Selva
- **Year published:** 2017
- **Journal or source:** Scientific Reports
- **Full citation:** Sergiel, A., Naves, J., Kujawski, P., Maślak, R., Serwa, E., Ramos, D., Fernández-Gil, A., Revilla, E., Zwijacz-Kozica, T., Zięba, F., Painer, J. and Selva, N. 2017. Histological, chemical and behavioural evidence of pedal communication in brown bears. Scientific Reports 7: 1052.
- **DOI:** 10.1038/s41598-017-01136-1
- **Access status:** Open access (CC BY 4.0)
- **PDF:** https://www.originalwisdom.com/wp-content/uploads/2026/11/2017_Sergiel_and_Naves_etal_histological-chemical-and-behavioural-evidence-of-pedal-communication-in-brown-bears.pdf

## Tags

- **Species:** Mammals > Brown bear
- **Region:** Europe > Poland; Europe > Spain
- **Tracking:** Paths; Tracking; Tracks; Tracks and signs identification
- **Behaviour and ecology:** Behaviour; Communication
- **Methods and technology:** Camera traps; Descriptive statistics
- **Data type:** New field data
- **Observer qualification:** Not reported
- **Discipline:** Behaviour and ecology
- **Year published:** 2017

## Detailed keywords

- **Species:** Studied: brown bear (Ursus arctos). Two dead bears examined for skin glands (a captive adult male euthanized for advanced degenerative joint disease, and a wild yearling male killed by another bear); six wild bears swabbed for scent (two adult males, one yearling male, three adult females); at least 15 individually recognizable wild bears on camera. Other species discussed from the literature only: polar bear (Ursus maritimus), American black bear (Ursus americanus), giant panda (Ailuropoda melanoleuca), aardwolf (Proteles cristatus), brown hyaena (Hyaena brunnea), spotted hyaena (Crocuta crocuta), Eurasian badger (Meles meles), ring-tailed lemur (Lemur catta), domestic cat, domestic dog, raccoon (Procyon lotor), wolf (Canis lupus), Chinese alligator (Alligator sinensis), termites and ants.
- **Location and habitat:** Scent samples: northern Carpathians, southern Poland. Behaviour: one long-used marking site under a rubbing tree in deciduous oak forest (Quercus species), Cantabrian Mountains, northwestern Spain. The paper does not say where the two bears used for skin samples came from.
- **Topics:** chemical (scent) communication; pedal (foot) scent marking; scent glands in the paws (apocrine and eccrine sweat glands, sebaceous glands); interdigital, metacarpal and metatarsal skin and footpads; sex differences in scent (sex coding); a marking gait of stepping and twisting the feet into old depressions; marked trails used for years by several bears; sniffing of pedal marks; links with tree rubbing; mating season; possible role of urine; possible visual and tactile signals from ground marks; age and gland development (puberty).
- **Statistics or models:** Descriptive statistics only (counts and percentages). Histology: counts of gland segments, glands per hair follicle, and the share of follicles with apocrine glands (in the Supplementary information). Chemistry: gas chromatography with mass spectrometry (GC-MS), compounds tentatively identified against the National Institute of Standards and Technology (NIST 11) library with the Automated Mass Spectrometry Deconvolution and Identification System (AMDIS). Inconsistencies: (1) the Results cite Fig. 1E for the yearling male, but the figure caption labels E as the adult male’s metatarsal skin (F is the yearling’s); (2) the text says eccrine glands were seen in the footpads of both bears, but the caption marks them only in the yearling’s footpad; (3) the Figure 2 caption gives a retention time of 38.4 minutes where Table 1 gives 38.54; (4) the Methods call the analysis “GC/MC”, elsewhere GC-MS.
- **Data type:** New field data. Video camera trap at one marking site, January 2012 to February 2015 (752 camera trap days); scent swabs from captured bears, 2014 to 2016; skin biopsies from two dead bears (dates not given).

## Synopsis

### 1. What they did

Bears live alone, roam large home ranges and do not defend territories, so they need good ways to leave messages for other bears. Most research has looked at tree rubbing. A study of polar bears found sweat glands in their paws, which suggested bears could leave scent simply by walking. The authors looked for the same thing in brown bears from three angles:

- Skin glands. They took skin samples from the paws (between the toes, the soles behind the pads, and the footpads) of two dead male bears, a captive adult and a wild yearling, and compared them under the microscope with skin from the lip and shoulder.

- Scent chemistry. They rubbed cotton swabs on the paws of six wild bears captured in the northern Carpathians of southern Poland (two adult males, one yearling male and three adult females; 24 swabs in all) and analysed the chemicals with gas chromatography and mass spectrometry.

- Behaviour. In the Cantabrian Mountains of northwestern Spain, a video camera trap hung above a rubbing tree at a spot where bears were known to mark with their feet. It ran from January 2012 to February 2015. They counted “pedal marking” when a bear placed their feet exactly in the existing ground marks (visible as depressions) while twisting each foot vigorously, and “sniffing of pedal marks” when a bear lowered their head and sniffed the tracks.

### 2. What they found

Glands in the paws

- No glands could be seen with the naked eye.

- Under the microscope, the skin between the toes and on the soles of the adult male had prominent apocrine sweat glands and sebaceous (oil) glands next to hair follicles, more prominent than in the lip and shoulder skin.

- The yearling had the same glands, but they were less developed.

- Both bears had a small number of eccrine sweat glands deep in the footpads.

Scent chemistry

- The swabs held 26 compounds. Twenty were found in every sample. Six were found in all samples from the adult males and in none from the adult females or the yearling male.

- Several were skin-borne carboxylic acids, which are common in mammal body odours. Cyclohexanone, suggested to be a typical scent-marking compound of large mammals, was in all bears.

- The male-only compounds included octanoic (caprylic) acid, thunbergene (a cembrenoid, which can come from animals or plants), two compounds of probable plant origin and two that could not be identified.

- The yearling male’s scent matched the adult females’ profile.

- No urine compounds (such as urea) were found.

Behaviour at the marking site

- Bears were active at the site on 18% of 752 camera trap days and appeared on 232 videos, in every month except January. At least 15 bears could be told apart by the shapes and colours of hair marks on their head and neck.

- Pedal marking appeared in 81 videos (35%). Adult males did 96% of it; sub-adults of unknown sex the other 4%.

- Bears marked with a special gait, stepping carefully and twisting their feet into the depressions left by earlier marking, so that the site carried a worn trail of footprints.

- Pedal marking was seen from March to November and peaked in the mating season (April to June, 54% of marking videos).

- Bears sniffed the pedal marks in 38 videos (16%), from March to December. Adult males did most of the sniffing (58%), but other bears, adult females included, sniffed them too.

### 3. What they concluded

- Brown bears have the glands needed to leave scent through their feet, and the scent of adults differs between the sexes, which suggests it could tell other bears whether the marker was male or female.

- The field data support this: males pedal-marked more often, especially in the mating season, at a site used for several years by a number of bears.

- The mix of oily sebaceous secretions and sweat could help the scent last in the environment.

- It is hard to say whether pedal scent comes only from the glands or also from urine, but no urine compounds were found.

- Because the marks are deep, worn depressions used for years, pedal marking may also send visual signals, not only scent.

- The yearling’s weaker glands and female-like scent suggest the glands become active with puberty.

- Brown bears are another solitary carnivore that communicates through their feet, and this may be an important way of passing on information.

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

The study did not use trailing or a tracks and signs survey. The pedal marks themselves are tracks: depressions worn into the ground by bears stepping into the same spots over years. The researchers recognized the marking site from these marks and other field signs seen during field work in the Cantabrian Mountains, and then watched it with a camera. On the videos they recorded when bears stepped into the old marks and when bears sniffed the tracks.

### 5. Tracker or observer certification

Not reported. The paper does not say who found the marking site or how the field signs were identified.

### 6. Other technologies, skills or innovations

- A video camera trap (Bushnell Trophy Camera) mounted above a rubbing tree, looking straight down, recording one-minute clips.

- Individual bears recognized from hair marks on the head and neck; age and sex judged from genitals, body shape and size, and accompanying bears.

- Skin biopsies stained with hematoxylin and eosin and examined at 100 times magnification.

- A pilot test of swab types, solvents and extraction times to find the best way to collect paw scent (wooden-core cotton swabs, hexane, two hours).

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

The paper does not discuss conservation directly. The authors say the findings add to what is known about how bears communicate and may encourage research on foot scent in other wide-ranging species.

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

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

- A bear’s footprints may carry scent, not just shape: the paws have glands that could leave a scent mark with every step, and adult males and females smell different.

- Lines of deep depressions near a rubbing tree, worn in by bears stepping into the same spots year after year, are a sign of pedal marking rather than ordinary travel. The study’s marked trail was used for years by several bears.

- Seeing a bear twist their feet into old marks, or sniff them, shows that the tracks themselves can be messages read by other bears.

## Cite this summary

Lawrence, K. 2026. Summary of: Histological, chemical and behavioural evidence of pedal communication in brown bears (Sergiel and Naves et al., 2017). Original Wisdom, Tracking Literature. https://www.originalwisdom.com/tracking-literature/2017-sergiel-naves-histological-chemical-behavioural-evidence/