Abstract: After 14C-labelled cortisol infusion in ponies and pigs, faecal samples were collected. Extraction of 0.5 g faeces with 5 ml 80–90 % methanol yielded the highest radioactivity in the supernatant. Most of the metabolites were ether soluble. After high performance liquid chromatography (HPLC), the presence of immunoreactive metabolites was demonstrated by measuring each HPLC fraction using enzyme immunoassays for cortisol, corticosterone and 11-oxoaetiocholanolone. Only the assay for 11-oxoaetiocholanolone revealed peaks with co-eluting radioactivity. For biological validation of the test system, adrenocorticotrophic hormone (ACTH) and dexamethasone were injected intravenously successively in both species (n = 6). Cortisol concentration in blood and the 11-oxoaetiocholanolone immunoreactive substances in faeces were determined. In horse faeces, basal values of 2.3–35.2 nmol/kg were measured. After ACTH administration, an increase (more than 200 % above basal values) of these metabolites was seen about 1 day after ACTH administration. After dexamethasone injection the levels decreased, reaching minimum concentrations 2 days after administration. In pigs, an increase in these metabolites was measured in only three animals after ACTH; dexamethasone did not cause a decrease. The stability of the samples after defecation was tested by storing samples from cows, horses and pigs at room temperature. It was shown that there was a significant increase in the concentration of measured cortisol metabolites in bovine, equine and porcine faeces after storage for 1 h, 4 h and 24 h, respectively. In frozen samples this effect was diminished after thawing samples at 40°C; thawing the samples at 95°C prevented an increase in immunoreactive substances.

Abstract: We tested the hypothesis that tapirs tolerate individuals from adjacent and overlapping home ranges if they are related. We obtained genetic data from fecal samples collected in the Balbina reservoir landscape, central Amazon. Samples were genotyped at 14 microsatellite loci, of which five produced high quality informative genotypes. Based on an analysis of 32 individuals, we inferred a single panmictic population with high levels of heterozygosity. Kinship analysis identified 10 pairs of full siblings or parent-offspring, 10 pairs of half siblings and 25 unrelated pairs. In 10 cases, the related individuals were situated on opposite margins of the reservoir, suggesting that tapirs are capable of crossing the main river, even after damming. The polygamous model was the most likely mating system for Tapirus terrestris. Moran's I index of allele sharing between pairs of individuals geographically close (<3 km) was similar to that observed between individual pairs at larger distances (>3 km). Confirming this result, the related individuals were not geographically closer than unrelated ones (W = 188.5; p = 0.339). Thus, we found no evidence of a preference for being close to relatives and observed a tendency for dispersal. The small importance of relatedness in determining spatial distribution of individuals is unusual in mammals, but not unheard of. Finally, non-invasive sampling allowed efficient access to the genetic data, despite the warm and humid climate of the Amazon, which accelerates DNA degradation.

Abstract: Deception, the use of false signals to modify the behaviour of the receiver, occurs in low frequencies even in stable signalling systems. For example, it can be advantageous for subordinate individuals to deceive in competitive situations. We investigated in a three-way choice task whether dogs are able to mislead a human competitor, i.e. if they are capable of tactical deception. During training, dogs experienced the role of their owner, as always being cooperative, and two unfamiliar humans, one acting ‘cooperatively’ by giving food and the other being ‘competitive’ and keeping the food for themselves. During the test, the dog had the options to lead one of these partners to one of the three potential food locations: one contained a favoured food item, the other a non-preferred food item and the third remained empty. After having led one of the partners, the dog always had the possibility of leading its cooperative owner to one of the food locations. Therefore, a dog would have a direct benefit from misleading the competitive partner since it would then get another chance to receive the preferred food from the owner. On the first test day, the dogs led the cooperative partner to the preferred food box more often than expected by chance and more often than the competitive partner. On the second day, they even led the competitive partner less often to the preferred food than expected by chance and more often to the empty box than the cooperative partner. These results show that dogs distinguished between the cooperative and the competitive partner, and indicate the flexibility of dogs to adjust their behaviour and that they are able to use tactical deception.

Abstract: Some domestic animals are thought to be skilled at social communication with humans due to the process of domestication. Horses, being in close relationship with humans, similar to dogs, might be skilled at communication with humans. Previous studies have indicated that they are sensitive to bodily signals and the attentional state of humans; however, there are few studies that investigate communication with humans and responses to the knowledge state of humans. Our first question was whether and how horses send signals to their potentially helpful but ignorant caretakers in a problem-solving situation where a food item was hidden in a bucket that was accessible only to the caretakers. We then examined whether horses alter their behaviours on the basis of the caretakers’ knowledge of where the food was hidden. We found that horses communicated to their caretakers using visual and tactile signals. The signalling behaviour of the horses significantly increased in conditions where the caretakers had not seen the hiding of the food. These results suggest that horses alter their communicative behaviour towards humans in accordance with humans’ knowledge state.

Abstract: Dogs learn a great deal from humans and other dogs. Previous studies of socially influenced learning between dogs have typically used a highly trained demonstrator dog who is unfamiliar to the observer. Because of this, it is unknown how dynamics between familiar dogs may influence their likelihood of learning from each other. In this study, we tested dogs living together in two-dog households on whether individual dogs’ rivalry scores were associated with performance on a local enhancement task. Specifically, we wanted to know whether dog rivalry impacted whether an observer dog would approach a plate from which a demonstrator dog had eaten all available food, or whether the observer dog would approach the adjacent plate that still contained food. Dog rivalry scores were calculated using the Canine Behavioral Assessment and Research Questionnaire and indicated each dog’s tendency to engage aggressively with the other household dog. Low-rivalry dogs were more likely to approach the empty plate than high-rivalry dogs when the observer dog was allowed to approach the plates immediately after the demonstrator had moved out of sight. This difference between low- and high-rivalry dogs disappeared, however, when observer dogs had to wait 5 s before approaching the plates. The same pattern was observed during a control condition when a human removed the food from a plate. Compared to low-rivalry dogs, high-rivalry dogs may pay less attention to other dogs due to a low tolerance for having other dogs in close proximity.