It is well-established that the odor of mammalian blood is attractive to top predators such as tigers and wolves and aversive to prey species such as mice and rats. Recent studies have shown that the mammalian blood odor component trans-4,5-epoxy-(E)-2-decenal (TED) elicits corresponding behavioral responses in these two groups of mammals. Here we assess whether a mesopredator, that is, a small-bodied carnivorous mammal that is both predator and prey, is attracted to or repelled by the odor of mammalian blood and TED. To this end, we assessed the behavior of a group of 15 captive meerkats (Suricata suricatta) when presented with wooden logs that were impregnated either with horse blood or with TED, and compared it to their behavior toward a fruity odor (iso-pentyl acetate) and a near-odorless solvent (diethyl phthalate). We found that the meerkats displayed significantly more interactions with the odorized wooden logs such as sniffing and pawing when these were impregnated with the two prey-associated odors compared to the two non-prey-associated odors. Most importantly, no significant difference was found in the number of interactions with the wooden logs impregnated with horse blood and TED, respectively. These results demonstrate that meerkats, despite being small-bodied mesopredators, are clearly attracted to the odor of mammalian blood. Further, the results suggest that a single blood odor component can be as efficient as the odor of real blood in eliciting behavioral responses in this herpestid mammal, similar to previous findings in feline and canine top predators.

Primates have been found to differ widely in their taste perception and studies suggest that a co-evolution between plant species bearing a certain taste substance and primate species feeding on these plants may contribute to such between-species differences. Considering that only platyrrhine primates, but not catarrhine or prosimian primates, share an evolutionary history with the neotropical plant Stevia rebaudiana, we assessed whether members of these three primate taxa differ in their ability to perceive and/or in their sensitivity to its two quantitatively predominant sweet-tasting substances. We found that not only neotropical black-handed spider monkeys, but also paleotropical black-and-white ruffed lemurs and Western chimpanzees are clearly able to perceive stevioside and rebaudioside A. Using a two-bottle preference test of short duration, we found that Ateles geoffroyi preferred concentrations as low as 0.05 mM stevioside and 0.01 mM rebaudioside A over tap water. Taste preference thresholds of Pan troglodytes were similar to those of the spider monkeys, with 0.05 mM for stevioside and 0.03 mM for rebaudioside A, whereas Varecia variegata was slightly less sensitive with a threshold value of 0.1 mM for both substances. Thus, all three primate species are, similar to human subjects, clearly more sensitive to both steviol glycosides compared to sucrose. Only the spider monkeys displayed concentration-response curves with both stevioside and rebaudioside A which can best be described as an inverted U-shaped function suggesting that Ateles geoffroyi, similar to human subjects, may perceive a bitter side taste at higher concentrations of these substances. Taken together, the results of the present study do not support the notion that a co-evolution between plant and primate species may account for between-species differences in taste perception of steviol glycosides.

Cross-fostering in canids, with captive-bred pups introduced into endangered wild populations, might aid conservation efforts by increasing genetic diversity and lowering the risk of inbreeding depression. The gray wolf (Canis lupus lupus) population in Scandinavia suffers from severe inbreeding due to a narrow genetic base and geographical isolation. This study aimed at evaluating the method to cross-foster wolf pups from zoo-born to zoo-born litters. The following was assessed: female initial acceptance of foster pups, growth rate in relation to age difference between foster pups and pups in recipient litters and survival over the first 33 weeks. The study included four litters added by two foster pups in each. The age differences between the foster pups and the recipient litters were 2-8 days. After augmentation, all four females accepted the foster pups, demonstrated by her moving the entire litter to a new den site. Growth rate was dependent on the age difference of the pups in the foster litters, with a considerably slower growth rate in the 8 days younger pups. However, these pups later appeared to be at no disadvantage. Foster pups had a higher survival rate than females pups, however, the causes of death were probably not kin or non-kin related. The results indicate that cross-fostering works in gray wolves and that this might be a plausible way to increase genetic variation in the wild population.

The Swedish wolf population (Canis lupus) descends from five individuals and is isolated and highly inbred with an average inbreeding coefficient of 0.27. In addition, inbreeding depression has led to reduced litter size and a high frequency of spinal disorders. To achieve the management goal of reducing the mean level of inbreeding, introductions into the wild population from a zoo conservation breeding program have been proposed by authorities. We used pedigree data of the wild and zoo populations to evaluate the extent to which the captive population can contribute genetic variation to the wild one. We measure genetic variation as founder alleles and founder genome equivalents. The two populations have three founders in common, but in spite of this common ancestry, our results show a potential to almost double genetic variation from 11.2 to 21.1 founder alleles. Similarly, the number of founder genome equivalents in the wild population can increase from the present 1.8 to 3.2, but this requires that almost 50 % of the wild gene pool consists of genes from the zoo population. Average kinship in the joint zoo and wild population is 0.15, which is above the management target of 0.1. Genetic contribution from the zoo has the potential to improve, but not solve, the genetically precarious situation of the wild population.

Book Abstract

Dolphin researchers have collected an impressive amount of data over the last twenty years, thanks to advances in technology for monitoring, recording, and analyzing dolphin behavior as well as increasing interest in exploring and modeling dolphins’ cognitive capacities. This volume offers a comprehensive reference to the latest research on dolphin communication and cognition, reporting on findings from both the laboratory and the field. The contributors review a wide range of topics, including vocalization, abstract reasoning abilities, imitation and learning, social cognition, echolocation, and ethical issues in working with cetaceans.The book begins by examining the dolphin brain and its evolution, the anatomy of its unique sound production and reception systems, and its sensory abilities. It next treats communication, reviewing the complexity of dolphins’ vocalization, and then describes research on cognition, from both experimental and developmental perspectives. Finally, the book considers the future of dolphin research, including a series of provocative questions that remain unanswered, posed by the volume’s expert contributors.

Only little is known about whether single volatile compounds are as efficient in eliciting behavioral responses in animals asthe whole complex mixture of a behaviorally relevant odor. Recent studies analysing the composition of volatiles inmammalian blood, an important prey-associated odor stimulus for predators, found the odorant trans-4,5-epoxy-(E)-2-decenal to evoke a typical ‘‘metallic, blood-like’’ odor quality in humans. We therefore assessed the behavior of captiveAsian wild dogs (Cuon alpinus), African wild dogs (Lycaon pictus), South American bush dogs (Speothos venaticus), andSiberian tigers (Panthera tigris altaica) when presented with wooden logs that were impregnated either with mammalianblood or with the blood odor component trans-4,5-epoxy-(E)-2-decenal, and compared it to their behavior towards a fruityodor (iso-pentyl acetate) and a near-odorless solvent (diethyl phthalate) as control. We found that all four species displayedsignificantly more interactions with the odorized wooden logs such as sniffing, licking, biting, pawing, and toying, whenthey were impregnated with the two prey-associated odors compared to the two non-prey-associated odors. Mostimportantly, no significant differences were found in the number of interactions with the wooden logs impregnated withmammalian blood and the blood odor component in any of the four species. Only one of the four species, the SouthAmerican bush dogs, displayed a significant decrease in the number of interactions with the odorized logs across the fivesessions performed per odor stimulus. Taken together, the results demonstrate that a single blood odor component can beas efficient in eliciting behavioral responses in large carnivores as the odor of real blood, suggesting that trans-4,5-epoxy-(E)-2-decenal may be perceived by predators as a ‘‘character impact compound’’ of mammalian blood odor. Further, the resultssuggest that odorized wooden logs are a suitable manner of environmental enrichment for captive carnivores.

Using a food-rewarded two-choice instrumental conditioning paradigm, we assessed the ability of Asian elephants, Elephasmaximus, to discriminate between 2 sets of structurally related odorants. We found that the animals successfully discriminatedbetween all 12 odor pairs involving members of homologous series of aliphatic 1-alcohols, n-aldehydes, 2-ketones,and n-carboxylic acids even when the stimuli differed from each other by only 1 carbon. With all 4 chemical classes, the elephantsdisplayed a positive correlation between discrimination performance and structural similarity of odorants in terms ofdifferences in carbon chain length. The animals also successfully discriminated between all 12 enantiomeric odor pairs tested.An analysis of odor structure–activity relationships suggests that a combination of molecular structural properties rather thana single molecular feature may be responsible for the discriminability of enantiomers. Compared with other species testedpreviously on the same sets of odor pairs (or on subsets thereof), the Asian elephants performed at least as well as miceand clearly better than human subjects, squirrel monkeys, pigtail macaques, South African fur seals, and honeybees. Furthercomparisons suggest that neither the relative nor the absolute size of the olfactory bulbs appear to be reliable predictors ofbetween-species differences in olfactory discrimination capabilities. In contrast, we found a positive correlation between thenumber of functional olfactory receptor genes and the proportion of discriminable enantiomeric odor pairs. Taken together,the results of the present study support the notion that the sense of smell may play an important role in regulating thebehavior of Asian elephants.

Using a food-rewarded two-choice instrumentalconditioning paradigm we assessed the ability of SouthAfrican fur seals, Arctocephalus pusillus, to discriminatebetween 12 enantiomeric odor pairs. The results demonstratethat the fur seals as a group were able to discriminatebetween the optical isomers of carvone, dihydrocarvone,dihydrocarveol, menthol, limonene oxide, a-pinene,fenchone (all p\0.01), and b-citronellol (p\0.05),whereas they failed to distinguish between the (?)- and(-)-forms of limonene, isopulegol, rose oxide, and camphor(all p[0.05). An analysis of odor structure–activityrelationships suggests that a combination of molecularstructural properties rather than a single molecular featuremay be responsible for the discriminability of enantiomericodor pairs. A comparison between the discrimination performanceof the fur seals and that of other species testedpreviously on the same set of enantiomers (or subsetsthereof) suggests that the olfactory discrimination capabilitiesof this marine mammal are surprisingly well developedand not generally inferior to that of terrestrial mammalssuch as human subjects and non-human primates. Further,comparisons suggest that neither the relative nor the absolutesize of the olfactory bulbs appear to be reliable predictorsof between-species differences in olfactorydiscrimination capabilities. Taken together, the results ofthe present study support the notion that the sense of smellmay play an important and hitherto underestimated role inregulating the behavior of fur seals.

The present study demonstrates that Asian elephants, Elephas maximus, can successfully be trained to cooperatein an olfactory discrimination test based on a food-rewarded two-alternative instrumental conditioningprocedure. The animals learned the basic principle of the test within only 60 trials and readily mastered intramodalstimulus transfer tasks. Further, they were capable of distinguishing between structurally related odorstimuli and remembered the reward value of previously learned odor stimuli after 2, 4, 8, and 16 weeks ofrecess without any signs of forgetting. The precision and consistency of the elephants' performance in testsof odor discrimination ability and long-term odor memory demonstrate the suitability of this method forassessing olfactory function in this proboscid species. An across-species comparison of several measuresof olfactory learning capabilities such as speed of initial task acquisition and ability to master intramodalstimulus transfer tasks shows that Asian elephants are at least as good in their performance as mice, rats,and dogs, and clearly superior to nonhuman primates and fur seals. The results support the notion thatAsian elephants may use olfactory cues for social communication and food selection and that the sense ofsmell may play an important role in the control of their behavior.

Recordings of the acoustic activity of free-swimming groups of echolocating dolphins increase the likelihood of collecting overlapping click trains, originating from multiple individuals, in the same set of data. In order to evaluate the click properties of each individual based on such recordings it is necessary to identify which clicks originate from which animal. This paper suggests a computationally efficient strategy to separate overlapping click trains originating from multiple free-swimming bottlenose dolphins, enabling echolocation analysis at an individual level on several animals. This technique is based on sequential matching of the frequency spectra of successive clicks. The clicks are grouped together as individual click trains if the correlation coefficients between clicks are higher than a pre-set threshold level. The robustness of the algorithm is tested by adding artificially generated white Gaussian noise and comparing the results with other comparable commonly used methods based on inter-click intervals, centroid frequencies, and amplitude levels. The described method is applicable to a variety of experimental and observational contexts, e. g., those regarding echolocation development of calves, the hypothesized acoustic "etiquette" among dolphins when investigating the same object, and the possible occurrence of eavesdropping in large dolphin pods.