The search for common characteristics between the musical abilities of humans and other animal species is still taking its first steps. One of the most promising aspects from a comparative point of view is the analysis of rhythmic components, which are crucial features of human communicative performance but also well-identifiable patterns in the vocal displays of other species. Therefore, the study of rhythm is becoming essential to understand the mechanisms of singing behavior and the evolution of human communication. Recent findings provided evidence that particular rhythmic structures occur in human music and some singing animal species, such as birds and rock hyraxes, but only 2 species of nonhuman primates have been investigated so far (Indri indri and Hylobates lar). Therefore, our study aims to consistently broaden the list of species studied regarding the presence of rhythmic categories. We investigated the temporal organization in the singing of 3 species of crested gibbons (Nomascus gabriellae, Nomascus leucogenys, and Nomascus siki) and found that the most prominent rhythmic category was isochrony. Moreover, we found slight variation in songs’ tempo among species, with N. gabriellae and N. siki singing with a temporal pattern involving a gradually increasing tempo (a musical accelerando), and N. leucogenys with a more regular pattern. Here, we show how the prominence of a peak at the isochrony establishes itself as a shared characteristic in the small apes considered so far.

The ability to vary the characteristics of one's voice is a critical feature of human communication. Understanding whether and how animals change their calls will provide insights into the evolution of language. We asked to what extent the vocalizations of penguins, a phylogenetically distant species from those capable of explicit vocal learning, are flexible and responsive to their social environment. Using a principal components (PCs) analysis, we reduced 14 vocal parameters of penguin's contact calls to four PCs, each comprising highly correlated parameters and which can be categorized as fundamental frequency, formant frequency, frequency modulation, and amplitude modulation rate and duration. We compared how these differed between individuals with varying degrees of social interactions: same-colony versus different-colony, same colony over 3 years and partners versus non-partners. Our analyses indicate that the more penguins experience each other's calls, the more similar their calls become over time, that vocal convergence requires a long time and relative stability in colony membership, and that partners' unique social bond may affect vocal convergence differently than non-partners. Our results suggest that this implicit form of vocal plasticity is perhaps more widespread across the animal kingdom than previously thought and may be a fundamental capacity of vertebrate vocalization.

Nowadays, most zoos have taken prominent and active positions in endangered species conservation and educating visitors about the value of biodiversity. However, to be effective and trusted in their mission, they must act ethically and have a good reputation. Yet, the drivers that can influence their reputation are still little investigated, and there are still few studies focused on assessing the reputation of these institutions. In the present work, we report the development of a tool, the Zoo Ethical Reputation Survey (ZERS), and its pilot application to assess the opinions of the visitors of two zoos, one in Italy and one in Germany, on drivers that may influence the ethical reputation of zoos. Preliminary results based on the answers of 274 respondents show that visitors’ opinions on zoos acting with ethical responsibility are correlated with emotional appeal and familiarity with these institutions. The application of ZERS can help zoos identify weaknesses in their reputation and develop new strategies to improve people’s attitudes towards them, bringing many benefits to the individual zoo and zoological institutions in general.

Environmental enrichment is a management tool used to promote positive animal welfare by stimulating species-specific behaviors and providing animals with opportunities to exert choice and control over the environment. Our study aimed to evaluate the combined effect of three enrichment types and environmental/individual factors (i.e., individual age and rank position) on the behavior of six adult Lemur catta hosted at Pistoia Zoo (Italy). We collected data from June to September 2013 using a within-subject experimental design consisting of five conditions: Baseline, Food-based enrichment, Physical enrichment, Auditory enrichment and No enrichment provided. We conducted six 30-minute observation sessions per sampling day (total = 107 h). We recorded the animals’ behavior via 2-minute focal animal sampling per individual per observation period and analyzed data with Generalized Linear Models. The study group only performed normal species-specific behaviors. Enrichments decreased stress-related behavioral patterns, whreas environmental and individual factors influenced the other recorded behaviors. Our study confirmed the usefulness of employing an integrated methodological approach to enrichment assessment for enhancing captive lemur care.

Zoos and aquaria have the ethical responsibility to provide animals under their care with conditions that promote good welfare. This study evaluated the combined influence of human presence and environmental factors on the behaviour of zoo-housed Asian small-clawed otters (Aonyx cinereus). Data collection was conducted on a pair hosted at Pistoia Zoo (Italy). Data were collected from July to September 2020 (over 14 days). We video-recorded the otters’ behaviours, using the continuous focal animal sampling, obtaining 42 h of observation per subject. The otters displayed a wide array of species-specific behaviours. Compared to previous captive studies, the subjects engaged less in locomotion, food-related and affiliative behaviours, and more in vigilance. Human–animal interactions were limited, and mostly elicited neutral or positive responses, except for begging behaviours performed towards caregivers. Time of day and animal identity were the main significant predictors for behaviours. No effects of visitor presence or background noise were detected. Nonetheless, increasing enrichment use could stimulate food-related behaviours, and reduce vigilance and begging. This study confirms the importance of applying an integrated approach to analyse the complexity of otters’ experiences, and provides insights to guide husbandry improvements.

Plains zebras are commonly hosted in zoos, but few welfare-related studies are available in the literature. This research aimed to assess the effect of enclosure design on two groups of captive zebras housed at the Giardino Zoologico di Pistoia - GZP (Italy) and Parco Faunistico Valcorba - PFV (Italy) through the analysis of behavior and enclosure use. The groups consisted of an adult pair and a male juvenile at GZP and six adult females at PFV. We collected data in 2019 over 19 sampling days using the continuous focal animal sampling technique. We performed 12 observation sessions per day, with each session lasting 30 min. We analyzed the subjects' behavioral time budget and enclosure use using Generalized Linear Mixed Models and the Electivity Index. The results showed that the time allocated to feeding behavior varied from 8-16% in the enclosure with gravel substrate (GZP) to 72-85% in the exhibit enriched with a pasture (PFV), with this last percentage resembling data reported for wild zebras. Results showed that institution was a significant predictor of feeding behavior, suggesting that the presence of a pasture can stimulate food-related behavioral patterns. Regarding enclosure use, the presence of hay and water troughs influenced the animals' space use. Our findings also suggest that evaluating both behavior and enclosure use can provide a more comprehensive overview of the welfare state of the animals. However, future studies are needed to better investigate the influence of social factors on the behavior and enclosure usage of captive Plains zebras.