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The role that visual discriminative ability plays among giant pandas in social communication and individual discrimination has received less attention than olfactory and auditory modalities. Here, we used an eye-tracker technology to investigate pupil fixation patterns for 8 captive male giant pandas Ailuropoda melanoleuca. We paired images (N =  26) of conspecifics against: 1) sympatric predators (gray wolves and tigers), and non-threatening sympatric species (golden pheasant, golden snub-nosed monkey, takin, and red panda), 2) conspecifics with atypical fur coloration (albino and brown), and 3) zookeepers/non-zookeepers wearing either work uniform or plain clothing. For each session, we tracked the panda's pupil movements and measured pupil first fixation point (FFP), fixation latency, total fixation count (TFC), and duration (TFD) of attention to each image. Overall, pandas exhibited similar attention (FFPs and TFCs) to images of predators and non-threatening sympatric species. Images of golden pheasant, snub-nosed monkey, and tiger received less attention (TFD) than images of conspecifics, whereas images of takin and red panda received more attention, suggesting a greater alertness to habitat or food competitors than to potential predators. Pandas' TFCs were greater for images of black-white conspecifics than for albino or brown phenotypes, implying that familiar color elicited more interest. Pandas reacted differently to images of men versus women. For images of women only, pandas gave more attention (TFC) to familiar combinations (uniformed zookeepers and plain-clothed non-zookeepers), consistent with the familiarity hypothesis. That pandas can use visual perception to discriminate intra-specifically and inter-specifically, including details of human appearance, has applications for panda conservation and captive husbandry. [ABSTRACT FROM AUTHOR]

Infant call structure should have evolved to elicit maximum maternal attention and investment. Neonates of giant pandas produce three types of vocalizations reported to be vitally important in the context of mother–infant communications. However, how cubs, 0–15 days old, communicate with their mothers to elicit maternal care remains unknown. We analyzed 12 different call parameters of 3475 squawks, 1355 squalls, and 491 croaks from 11 captive giant panda (Ailuropoda melanoleuca) neonates from age 0 to 15 days. In playback experiments, we also tested whether mothers could detect ultrasound. Our results show that neonates use broadband calls with ultrasonic frequencies up to 65 kHz to convey information about their physiological needs and to attract maternal care. In playback experiments, we tested if mothers reacted differently to broadband calls (BBC) than to artificially altered calls that included only frequencies <20 kHz (AUDC) or calls that included only frequencies >20 kHz (USC). Playback confirmed that, although adult females responded significantly less often to USC, BBC than to or AUDC, they could detect USC, BBC and generally made appropriate behavioral responses, indicating a potential benefit for neonates to utilize ultrasonic and broadband frequencies. Our findings provide a new insight into mother–infant communication in giant pandas and will be helpful for reducing the mortality of cubs, younger than 1 month old, in captivity. [ABSTRACT FROM AUTHOR]

Exposuretosexual stimuli can leadtoincreased aggressioninmale mammals, but it isunclear whether the aggression is related to the receptiveness of the females. Interactions with receptive females elicit testosterone (T) pulses that are important for sexual behaviors. We investigated the effects of male-female interactions on subsequent aggressive behaviors and T responses in the golden hamster (Mesocricetus auratus (Waterhouse, 1839)). Three groups (n = 18, 17, and 18) of males were exposed to receptive females, nonreceptive females, and blank (control), respectively. Then, we randomly chose eight animals from each group and measured their aggression toward an unfamiliar male conspecific; the remaining 29 males were used for a T assay (to avoid effects of aggression on T levels). The results show that interactions with females led to significantly higher male aggression and T levels than were found in control males. The increased aggression was not related to the receptiveness of the females, but receptive females elicited higher levels of T in males than nonreceptive females. Our findings suggest that the elevated aggression following the sexual encounter may serve to defend the female, by enhancing the ability of males to exclude other males from the vicinity of females, whereas the post-encounter T release may serve to assist mating behaviors and reproductive success. Key words: aggression, golden hamster, Mesocricetus auratus, receptiveness, sexual encounter, testosterone. L'exposition à des stimuli sexuels peut mener à une plus grande agressivité chez les mammifères mâles, mais la présence d'un lien entre cette agressivité et la réceptivité des femelles n'est pas bien établie. Les interactions avec des femelles réceptives provoquent une production ponctuelle de testostérone (T) qui est importante pour les comportements sexuels. Nous avons examiné les effets d'interactions mâle-femelle sur les comportements agressifs subséquents et les réactions de la T chez le hamster doré (Mesocricetus auratus (Waterhouse, 1839)). Trois groupes (n = 18, 17, and 18) de mâles ont été exposés à des femelles réceptives, à des femelles non réceptives et à des blancs (témoins). Nous avons ensuite sélectionné aléatoirement huit individus de chaque groupe et mesuré leur agressivité envers un mâle conspécifique non familier; les autres 29 mâles ont été utilisés pour l'analyse de la T (pour éviter des effets de l'agressivité sur les concentrations de T). Les résultats montrent que les mâles ayant interagi avec les femelles présentent une agressivité et des concentrations de T significativement plus importantes que les mâles témoins. Cette agressivité accrue n'est pas reliée à la réceptivité des femelles, bien que les femelles réceptives aient élicité de plus fortes concentrations de T chez les mâles que les femelles non réceptives. Nos constatations portent à croire que l'agressivité élevée suivant un rapport sexuel pourrait servir à défendre la femelle en accroissant la capacité du mâle d'exclure d'autres mâles des environs de cette dernière, alors que la libération de T après le rapport pourrait servir à soutenir des comportements d'accouplement et le succès de reproduction. [Traduit par la Rédaction] Mots-clés : agressivité, hamster doré, Mesocricetus auratus, réceptivité, rapport sexuel, testostérone., Introduction Sexual selection theory predicts that when females are alimited resource, males will increase aggression and challenge one another for access to females (Andersson 1994; Jirotkul 1999; Xu et al. [...]

Vocal individuality is a prerequisite for individual recognition, especially when visual and chemical cues are not available or effective. Vocalizations encoding information of individual identity have been reported in many social animals and should be particularly adaptive for species living in large and complexly organized societies. Here, we examined the individuality in coo calls of adult male golden snub-nosed monkeys (Rhinopithecus roxellana) living in a large and multilevel society. Coo calls are one of the most frequently occurring call types in R. roxellana and likely serve as the signals for contact maintenance or advertisement in various contexts including group movement, foraging, and resting. From April to October 2016, April to July 2017, and September to October 2017, we recorded a total of 721 coo calls from six adult males in a provisioned, free-ranging group and one adult male in captivity in Shennongjia National Park, China. We selected 162 high-quality recordings to extract 14 acoustic parameters based on the source-filter theory. Results showed that each of all parameters significantly differed among individuals, while pairwise comparisons failed to detect any parameter that was different between all pairs. Furthermore, a discriminant function analysis indicated that the correct assignment rate was 80.2% (cross-validation: 67.3%), greater than expected by chance (14.3%). In conclusion, we found evidence that coo calls of adult male R. roxellana allowed the reliable accuracy of individual discrimination complementarily enhanced by multiple acoustic parameters. The results of our study point to the selective pressures acting on individual discrimination via vocal signals in a highly gregarious forest-living primate. [ABSTRACT FROM AUTHOR]

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