Behavioural diversity as a potential welfare indicator for professionally managed chimpanzees (Pan troglodytes): Exploring variations in calculating diversity using species-specific behaviours

Behavioural diversity may serve as a positive indicator of animal welfare that can be applied in long-term monitoring schemes in managed settings (eg zoos, laboratories, farms). Behavioural diversity is often higher when animals live in stimulating environments and experience positive events. Unfortunately, welfare researchers have not adopted consistent, standardised approaches to measuring behavioural diversity. The goal of this exploratory study was to utilise data from 41 adult chimpanzees (Pan troglodytes) housed across 16 zoological institutions to examine various models of Shannon's Diversity Index. Specifically, we investigated the impact of: combining versus splitting behaviours, including only positive behaviours, including human interaction, and considering recipient behaviours. We evaluate how the inclusion or exclusion of different behaviours impacts the relationship of behavioural diversity with: (i) concentrations of faecal glucocorticoid metabolites (GCM), a common indicator of adrenal activity; (ii) concentrations of immunoglobulin-A (IgA), an indicator of immune function and potential indicator of positive welfare; and (iii) stereotypic behaviour, a validated indicator of poor welfare. Most indices had significant negative relationships with faecal GCM. Animals that express a variety of behaviours from their species-typical repertoire have lower average faecal GCM concentrations and are likely experiencing better welfare. We did not find significant relationships between the behavioural diversity indices and IgA concentrations. Two indices were inversely associated with stereotypic behaviour. Our findings provide additional support for using Shannon's Diversity Index to calculate behavioural diversity as a robust, valid measure of positive welfare. However, future publications must justify the process for including or excluding behaviours from calculations.

Three-dimensional modelling, disparity and ecology of the first Cambrian apex predators

Radiodonts evolved to become the largest nektonic predators in the Cambrian period, persisting into the Ordovician and perhaps up until the Devonian period. They used a pair of large frontal appendages together with a radial mouth apparatus to capture and manipulate their prey, and had evolved a range of species with distinct appendage morphologies by the Early Cambrian (approx. 521 Ma). However, since their discovery, there has been a lack of understanding about their basic functional anatomy, and thus their ecology. To explore radiodont modes of feeding, we have digitally modelled different appendage morphologies represented by Anomalocaris canadensis , Hurdia victoria , Peytoia nathorsti, Amplectobelua stephenensis and Cambroraster falcatus from the Burgess Shale. Our results corroborate ideas that there was probably a significant (functional and hence behavioural) diversity among different radiodont species with adaptations for feeding on differently sized prey (0.07 cm up to 10 cm). We argue here that Cambroraster falcatus appendages were suited for feeding on suspended particles rather than filtering sediment. Given the limited dexterity and lack of accessory feeding appendages as seen in modern arthropods, feeding must have been inefficient and ‘messy’, which may explain their subsequent replacement by crown-group arthropods, cephalopods and jawed vertebrates.

Behavioural Diversity Study in Bottlenose Dolphin (Tursiops truncatus) Groups and Its Implications for Welfare Assessments

In the recent past, animal welfare studies have tried to determine the best animal welfare measures and indicators. Expression of behavioural diversity is considered a potential positive welfare indicator, and to the authors’ knowledge, it has not been validated nor studied in cetaceans. For the first time, a behavioural diversity study on bottlenose dolphins (Tursiops truncatus) groups was conducted at six European facilities. The study was carried out by the animal care staff, biologists and veterinarians and included 54 dolphins housed in several group compositions at the different participating facilities. The goal of our study was to analyse behavioural diversity in bottlenose dolphins at the group level to investigate how particular factors might impact the diversity of behaviours within the group and to discuss its implications for dolphin welfare assessments. Eight factors (i.e., “observer location”, “number of individuals”, “age class”, “sex”, “social grouping”, “presence/absence of leading male”, “presence/absence of visitors” and “enrichment provision”) impacted the behavioural diversity of the observed groups, while no significant impact of the factors “time of day” and “activity before/after observation” could be found. Our study showed the feasibility of this kind of approach for cetaceans under professional care and the relevance to considering this parameter in dolphin welfare studies, despite certain limitations that warrant further research.

Author Correction: Environmental variability supports chimpanzee behavioural diversity

A Correction to this paper has been published: https://doi.org/10.1038/s41467-021-21010-z.

Environmental variability supports chimpanzee behavioural diversity

Large brains and behavioural innovation are positively correlated, species-specific traits, associated with the behavioural flexibility animals need for adapting to seasonal and unpredictable habitats. Similar ecological challenges would have been important drivers throughout human evolution. However, studies examining the influence of environmental variability on within-species behavioural diversity are lacking despite the critical assumption that population diversification precedes genetic divergence and speciation. Here, using a dataset of 144 wild chimpanzee (Pan troglodytes) communities, we show that chimpanzees exhibit greater behavioural diversity in environments with more variability — in both recent and historical timescales. Notably, distance from Pleistocene forest refugia is associated with the presence of a larger number of behavioural traits, including both tool and non-tool use behaviours. Since more than half of the behaviours investigated are also likely to be cultural, we suggest that environmental variability was a critical evolutionary force promoting the behavioural, as well as cultural diversification of great apes.

Behavioural diversity of bonobo prey preference as a potential cultural trait

The importance of cultural processes to behavioural diversity in our closest living relatives is central to revealing the evolutionary origins of human culture. However, the bonobo is often overlooked as a candidate model. Further, a prominent critique to many examples of proposed animal cultures is premature exclusion of environmental confounds known to shape behavioural phenotypes. We addressed these gaps by investigating variation in prey preference between neighbouring bonobo groups that associate and overlap space use. We find group preference for duiker or anomalure hunting otherwise unexplained by variation in spatial usage, seasonality, or hunting party size, composition, and cohesion. Our findings demonstrate that group-specific behaviours emerge independently of the local ecology, indicating that hunting techniques in bonobos may be culturally transmitted. The tolerant intergroup relations of bonobos offer an ideal context to explore drivers of behavioural phenotypes, the essential investigations for phylogenetic constructs of the evolutionary origins of culture.

Behavioural diversity of bonobo prey preference as a potential cultural trait

The importance of cultural processes to behavioural diversity, especially in our closest living relatives, is central for revealing the evolutionary origins of human culture. Whereas potential cultural traits are extensively investigated in chimpanzees, our other closest living relative, the bonobo, is often overlooked as a candidate model. Further, a prominent critique to many examples of proposed animal cultures is premature exclusions of environmental confounds known to shape behavioural phenotypes. We addressed these gaps by investigating variation in prey preference expression between neighbouring bonobo groups that associate and share largely overlapping home ranges. We find specific group preference for duiker or anomalure hunting that are otherwise unexplained by variation in spatial usage of hunt locations, seasonality or sizes of hunting parties. Our findings demonstrate that group-specific behaviours emerge independently of the local ecology, indicating that hunting techniques in bonobos may be culturally transmitted. We suggest that the tolerant intergroup relations of bonobos offer an ideal context to explore drivers of behavioural phenotypes, the essential investigations for phylogenetic constructs of the evolutionary origins of culture.