The formation of social groups is an adaptive behaviour that can provide protection from predators, improve foraging and facilitate social learning. However, the costs of proximity can include competition for resources, aggression and kleptoparasitism meaning that the decision whether to interact represents a trade-off. Here we show that zebrafish harbouring a mutation inendothelin receptor aa(ednraa) form less cohesive shoals than wild-types.ednraa^−/−mutants exhibit heightened aggression and decreased whole-body cortisol levels suggesting that they are dominant. These behavioural changes correlate with a reduction of parvocellular arginine vasopressin (AVP)-positive neurons in the preoptic area, an increase in the size of magnocellular AVP neurons and a higher concentration of 5-HT and dopamine in the brain. Manipulation of AVP or 5-HT signalling can rescue the shoaling phenotype ofednraa^−/−providing an insight into how the brain controls social interactions.

With dogs being the most commonly owned companion animal in the United Kingdom, knowledge about dog demographics is important in understanding the impact of dogs on society. Furthermore, understanding the demography of dog owners is also important to better target support to dogs and their owners to achieve optimal welfare in the canine population. Combining natural fluctuations in the population and unprecedented events such as the COVID-19 pandemic, the need for an up-to-date large-scale dataset is even more paramount. In order to address this, Dogs Trust launched the ‘National Dog Survey’ to provide a large population-level dataset that will help identify key areas of concern and needs of owners and their dogs. The online survey was completed by a total of 354,046 respondents owning dogs in the UK, providing data for 440,423 dogs. The results of this study highlight dog demographics, including acquisition and veterinary factors, as well as owner demographic and household information. Finally, general trends in ownership, and more specifically those following the COVID-19 pandemic, are described. This paper’s findings provide valuable insight into the current population of dogs and their owners in the UK, allowing for the most appropriate products, services, interventions and regulations to be developed, reducing the likelihood of negative welfare outcomes such as health and behaviour issues, relinquishment or euthanasia. Furthermore, with significant changes to the dog population following the COVID-19 pandemic highlighted, this dataset serves as an up-to-date baseline for future study comparisons to continue to monitor trends and patterns of the dog population and dog owners going forwards.

Group living is widespread among animal species, and comes with a number of costs and benefits associated with foraging, predator avoidance and reproduction. It is largely unknown, however, whether individuals sacrifice exposure to their own preferred or optimal environmental conditions so they can remain part of a social group. Here, we demonstrate that individual three-spine sticklebacks vary in the degree to which they forego exposure to their preferred ambient temperature so they can associate with a group of conspecifics. Individual fish varied widely in preferred temperature when tested in isolation. When the same individuals were presented with a choice of a warm or cold thermal regime in the presence of a social group in one of the environments, fish spent more time with the group if it was close to their own individually preferred temperature. When a group was in a relatively cool environment, focal individuals that were more social deviated most strongly from their preferred temperature to associate with the group. Standard and maximum metabolic rate were not related to temperature preference or thermal compromise. However, individuals with a higher standard metabolic rate were less social, and so energetic demand may indirectly influence the environmental costs experienced by group members. The reduced tendency to engage with a social group when there is a large difference between the group temperature and the individual's preferred temperature suggests a role for temperature in group formation and cohesion that is mediated by individual physiology and behaviour. Together, these data highlight exposure to non-preferred temperatures as a potential cost of group membership that probably has important but to date unrecognized implications for metabolic demand, energy allocation, locomotor performance and overall group functioning.

Limited socialisation can contribute to the development of undesirable dog behaviours. The COVID-19 lockdown potentially limited socialisation opportunities, which may negatively impact the future behaviour of puppies raised during lockdown. Data were gathered from longitudinal study participants in the United Kingdom/Republic of Ireland via multiple questionnaires between May 2016 and November 2022. The impact of age and lockdown phase (pre-, during, and post-) on the types of socialisation experiences of 8-to-19-week-old puppies and the recency of socialisation experiences of approximately 6-month-old puppies were examined. Puppies under 19-weeks had significantly more types of socialisation experiences (from a predefined list) as they aged, and pre-lockdown compared to post-lockdown, but not between other lockdown phases. Most 6-month-old puppies had met a new adult or dog outside the household, a familiar dog, and/or a child within the last 1–7 days, and this was similar between lockdown phases. During lockdown, 6-month-old puppies experienced longer periods between meeting a new adult in their home. Puppies were hypothesised to have had fewer experiences during lockdown, but this was not found. However, the quantity and quality of these experiences may have been affected. Future research within this longitudinal study will explore relationships between the timing and type of experiences had by puppies and their subsequent behaviour.

Dog behaviour that owners perceive as undesirable can compromise dog welfare, impact the owner and human–animal bond, and may result in relinquishment or euthanasia. This longitudinal study explored the type and percentage of owner-perceived undesirable behaviours in 6, 9, 12, 15 and 18-month-old dogs, and examined differences in the prevalence of four commonly reported behaviours across these timepoints. Owners reported their dog’s undesirable behaviours via free-text answers in self-administered surveys. Of the five timepoints studied, the highest percentage of dogs reported by their owners to display one or more undesirable behaviours was in the 12-month survey (42.1%, 513/1219). Barking, jumping up, pulling on the lead and recall issues were the most commonly reported behaviours across all timepoints. Binomial mixed-effects models revealed a significant difference in prevalence of barking, pulling on the lead and recall issues between the timepoints, but no significant difference in the occurrence of jumping up at people. With many dogs in this study being reported to display undesirable behaviour, it is crucial that stakeholders inform dog owners, especially first-time owners, about the behaviours they may experience from young dogs and where to seek appropriate training/behaviour advice to potentially reduce the risk of relinquishment related to behaviour.

Animals living in groups tend to express less variable behaviour than animals living alone. It is widely assumed that this difference reflects, at least in part, an adaptive response to contrasting selection pressures: group-living should favour the evolution of more uniform behaviour whereas lone-living should favour behaviour that is less predictable. Empirical evidence linking these contrasting selection pressures to intrinsic differences in behavioural variability is, however, largely lacking. The desert locust, Schistocerca gregaria, manifests in two very distinct eco-phenotypes, a lone-living cryptic “solitarious phase” and a swarming “gregarious phase” that aggregates into very large and dense groups. This “phase polyphenism” has evolved in response to contrasting selection pressures that change rapidly and unpredictably. Phase differences in mean behaviour are well-characterised, but no previous study has considered differences in variability. Here we used locust phase polyphenism to test the hypothesis that group living leads to the evolution of reduced intrinsic variability in behaviour. We measured two behaviours in both phenotypes: locomotor activity in the presence of conspecifics, and locomotor hesitation in approaching food when alone. We assayed each individual repeatedly and estimated variability relative to the mean in log-normal mixed-effects models that explicitly account for the means-variance dependency in the behavioural measures. Our results demonstrate that relative behavioural variability differs between the two phases in line with predictions from ecological theory: both within-individual and between-individual variability were lower in the group-living gregarious phenotype. This contrasts with previous studies on social niche construction in spiders and crickets, and highlights the importance of social ecology: in animals that form non-social collectives, such as locusts, reduced individual behavioural variability is key for coherent collective behaviour. The differences in variability persisted when gregarious locusts were tested in isolation and solitarious locusts were tested in groups, indicating that they arise not simply as flexible reactions to different social contexts, but are intrinsic to the individual animals of each phase. This “variance polyphenism” in locusts provides empirical evidence that evolutionary adaptation for group living has driven a reduction in within- and between-individual behavioural variability.