Knowing Me, Knowing You: Anal Gland Secretion of European Badgers (Meles meles) Codes for Individuality, Sex and Social Group Membership

European badgers, Meles meles, are group-living in the UK, and demarcate their ranges with shared latrines. As carnivores, badgers possess paired anal glands, but olfactory information on the content of badger anal gland secretion (AGS) is largely uninvestigated. Here, we examined the volatile organic compounds (VOCs) of AGS samples from 57 free-living badgers using solid-phase microextraction (SPME) and gas chromatography—mass spectrometry. AGS was rich in alkanes (C7–C15, 14.3% of identified compounds), aldehydes (C5–C14, 9.7%), phenols (C6–C15, 9.5%), alcohols (C5–C10, 7.3%), aromatic hydrocarbons (C6–C13, 6.8%), ketones (C6–C13, 6.3%) and carboxylic acids (C3–C12, 5.6%) and contained a variety of esters, sulfurous and nitrogenous compounds, and ethers. The number of VOCs per profile ranged from 20 to 111 (mean = 65.4; ± 22.7 SD), but no compound was unique for any of the biological categories. After normalization of the raw data using Probabilistic Quotient Normalization, we produced a resemblance matrix by calculating the Euclidian distances between all sample pairs. PERMANOVA revealed that AGS composition differs between social groups, and concentration and complexity in terms of number of measurable VOCs varies between seasons and years. AGS VOC profiles encode individual identity, sex and vary with female reproductive state, indicating an important function in intraspecific communication. Because AGS is excreted together with fecal deposits, we conclude that chemical complexity of AGS enables particularly latrine-using species, such as badgers, to advertise more complex individual-specific information than in feces alone.

Odour-based kin discrimination in the cooperatively breeding meerkat

Kin recognition is a useful ability for animals, facilitating cooperation among relatives and avoidance of excessive kin competition or inbreeding. In meerkats, Suricata suricatta, encounters between unfamiliar kin are relatively frequent, and kin recognition by phenotype matching is expected to avoid inbreeding with close relatives. Here, we investigate whether female meerkats are able to discriminate the scent of unfamiliar kin from unfamiliar non-kin. Dominant females were presented with anal gland secretion from unfamiliar individuals that varied in their relatedness. Our result indicates that females spent more time investigating the scent of related than unrelated unfamiliar individuals, suggesting that females may use a phenotype matching mechanism (or recognition alleles) to discriminate the odour of their kin from the odour of their non-kin. Our study provides a key starting point for further investigations into the use of kin recognition for inbreeding avoidance in the widely studied meerkat.

Subspecies discrimination in the Scandinavian beaver (Castor fiber): combining behavioral and chemical evidence

Geographic isolation is one of several models that has been proposed to explain the evolutionary course of speciation. In this study, we examined how geographical isolation may affect subspecies discrimination in the free-ranging Scandinavian beaver (Castor fiber fiber L., 1758) by simulating a territorial intrusion by using scent (castoreum and anal gland secretion) from a con-subspecific (N = 8 for castoreum and N = 7 for anal gland secretion) and a hetero-subspecific (Castor fiber albicus Matschie, 1907; N = 2 for both castoreum and anal gland secretion). Direct observations of 33 families during evenings showed that beavers (i) sniffed castoreum but not anal gland secretion from C. f. fiber significantly longer than from C. f. albicus and (ii) responded aggressively (i.e., stood on the mound on their hind feet, pawing and (or) overmarking) significantly longer to castoreum but not anal gland secretion from C. f. fiber than from C. f. albicus. When experimental scent mounds were allowed to remain overnight, the response was significantly stronger to castoreum but not to anal gland secretion from C. f. fiber than from C. f. albicus. Gas chromatographic comparisons of castoreum and anal gland secretion from the two subspecies supported our behavioral observations for castoreum but not for anal gland secretion. These findings suggest that geographical isolation has developed discriminatory abilities in C. f. fiber. We further suggest that the proximate factors involved are of environmental origin.

Eurasian beavers (Castor fiber) behavioral response to simulated territorial intruders

Eurasian beavers (Castor fiber) live in family groups that defend territories against other conspecifics. Part of this territorial defence involves constructing scent mounds near the stream bank within territories and marking them with castoreum, a urine-based fluid from the castor sacs, and (or) anal-gland secretion. The aim of this study was to test the hypothesis that Eurasian beavers show one or more forms of territorial behavior when an intruder, simulated in the form of experimental scent mounds (ESMs), has scent-marked inside the territory. We predicted that beavers would show a stronger response to ESMs with castoreum than to those without. Results showed that 85% of all beaver families (N = 20) made one or more behavioral responses to ESMs marked with castoreum from foreign adult males, whereas no ESMs presented without castoreum received a response. We therefore conclude that a main function of territorial marking by beavers is to advertise spatially related dominance status, thereby providing opportunities for intruders to assess the presence of the owner and reducing the cost and risks of agonistic conflict for both the owner and intruders. Additionally, it appears to be the scent emitted from an ESM and not the sight of it to which beavers respond.