The Welfare of Domestic Goats (Capra hircus) in a Zoo-Based Animal-Visitor Interaction Program

We investigated whether the welfare of domestic goats in an animal-visitor interaction experience at a zoo was affected by the presence and behavior of visitors. We considered how the number of visitors in the goats’ habitat and visitor proximity to the goats impacted goat behavior. We also considered the goats’ behavior toward visitors, use of retreat space, and whether the visitors’ interaction style, specifically, how the visitors groomed the goats, was predictive of changes in the goats’ behavior. We conducted 29 hr of focal follows on 7 domestic goats (Capra hircus) at Lincoln Park Zoo, and analyzed data using mixed effects models. We found that goats preferred to be in the visitor yard as visitor numbers increased, and goat behaviors did not change as visitor numbers increased to the maximum allowed (16 people). There were no differences in rates of conspecific aggression or affiliation based on visitor presence or visitor interactions. However, there was a decrease in feeding and increase in self-maintenance behaviors specifically while visitors were in close proximity and interacting with goats. Furthermore, visitor-directed behavior, specifically head tossing, was more common when visitors groomed goats in an improper way. Overall, this study demonstrates that domestic goat welfare was relatively unaffected by the simple presence of visitors when maximum visitor limits were in place and retreat options were available, but that goats were sensitive to visitor interaction styles. These findings support the idea that domestic goats may be appropriate candidates for human-visitor interaction programs under specific conditions.

Conspecific aggression strategies are conditioned by environmental, social and intrinsic variables in breeding blue tits Cyanistes caeruleus

Territorial behaviour arises as a strategy of ensuring individuals’ access to a variety of potentially limiting resources. While aggressiveness is a well-studied widespread trait across taxa, the mechanisms that allow for a range of aggressive phenotypes to coexist in the wild remains unclear. In this study, we analyse environmental, social and intrinsic variables that can modulate the expression of different strategies of male–male aggressiveness. Furthermore, through network analysis we explore the role of this trait in the establishment of territories during the breeding season as the intensity of different aggressiveness strategies may limit or grant access to resources. Simulating territorial intrusions during the early incubation period, we assessed the aggressiveness of breeding male blue tits (Cyanistes caeruleus). We defined three types of conspecific aggressiveness (nonconfrontational intimidating, nonconfrontational cautious and confrontational) and analysed the effect of habitat structure, territory quality, presence of other breeding species and male condition on the type and intensity of the aggressive display. The results obtained suggest that yearling males rely on intimidating behaviour more than older males, that perform more cautious displays. Furthermore, smaller and heavier males opted for confrontational strategies. The density and nature of neighbours, as well as the territory quality and the habitat structure, also conditioned the intensity and type of display. Surprisingly, the network analysis revealed that the intensity of male–male aggressive displays did not condition the establishment of breeding territories. Our results suggest that aggressiveness is a context-specific trait shaped by a complex array of environmental and intrinsic parameters.

Venom and Social Behavior: The Potential of Using Spiders to Evaluate the Evolution of Sociality under High Risk

Risks of sociality, including competition and conspecific aggression, are particularly pronounced in venomous invertebrates such as arachnids. Spiders show a wide range of sociality, with differing levels of cannibalism and other types of social aggression. To have the greatest chance of surviving interactions with conspecifics, spiders must learn to assess and respond to risk. One of the major ways risk assessment is studied in spiders is via venom metering, in which spiders choose how much venom to use based on prey and predator characteristics. While venom metering in response to prey acquisition and predator defense is well-studied, less is known about its use in conspecific interactions. Here we argue that due to the wide range of both sociality and venom found in spiders, they are poised to be an excellent system for testing questions regarding whether and how venom use relates to the evolution of social behavior and, in return, whether social behavior influences venom use and evolution. We focus primarily on the widow spiders, Latrodectus, as a strong model for testing these hypotheses. Given that successful responses to risk are vital for maintaining sociality, comparative analysis of spider taxa in which venom metering and sociality vary can provide valuable insights into the evolution and maintenance of social behavior under risk.

Sniffing the Human Body-Volatile Hexadecanal Blocks Aggression in Men but Triggers Aggression in Women

Body-volatiles can effectively trigger or block conspecific aggression in terrestrial mammals. Here we tested whether hexadecanal (HEX), a human body-volatile implicated as a mammalian-wide social cue, impacts human aggression. Using validated behavioural paradigms, we observed a remarkable dissociation: sniffing HEX blocked aggression in men, but triggered aggression in women. Next, using functional brain imaging, we uncovered a pattern of brain activity mirroring behaviour: In both men and women, HEX increased activity in the left angular gyrus, an area implicated in perception of social cues. Hex then modulated functional connectivity between the angular gyrus and a brain network implicated in social appraisal (temporal pole) and aggressive execution (amygdala and orbitofrontal cortex) in a sex-dependent manner consistent with behaviour: increasing connectivity in men, but decreasing connectivity in women. These findings implicate sex-specific social chemosignaling at the mechanistic heart of human aggressive behaviour.

Acute aggressive behavior perturbates the oxidative status of a wild bird independently of testosterone and progesterone

Aerobically demanding activities like aggression can lead to an elevated oxidative metabolism affecting the concentration of pro-oxidant and antioxidant compounds and can result in an overall perturbation of the oxidative status. Aggression may also alter the oxidative status indirectly through an increase in testosterone and progesterone concentrations. Given that changes in the oxidative status could represent a physiological cost of aggression, we tested the hypothesis that acute conspecific aggression impairs the oxidative status and evaluated the role of testosterone and progesterone as potential mediators. To achieve this, we experimentally manipulated the aggressive behavior of wild female and male birds and measured the concentrations of pro-oxidants, enzymatic- and non-enzymatic antioxidants, testosterone and progesterone in blood. After 20 minutes of conspecific aggressive behavior, both sexes had lower concentrations of non-enzymatic antioxidants than control individuals. This effect was independent of testosterone and progesterone concentrations, and much stronger in females than in males. Further, only in females (but not in males) being more aggressive came at the expense of lower antioxidant concentration. We provide the first experimental evidence that acute aggressive behavior perturbates the oxidative state of a wild vertebrate independently of testosterone and progesterone, with potential ecological and evolutionary implications given the role of the redox system in shaping life-history traits.

Spatial ecology of male hippopotamus in a changing watershed

The obligate dependency of the common hippopotamus, Hippopotamus amphibius, on water makes them particularly vulnerable to hydrological disturbances. Despite the threats facing this at-risk species, there is a lack of information regarding H. amphibius spatial ecology. We used high-resolution tracking data of male H. amphibius to assess home range size, movement mode (e.g. residency and migratory movements), and resource selection patterns. We compared these results across seasons to understand how hydrological variability influences H. amphibius movement. Our study watershed has been severely impacted by anthropogenic water abstraction causing the river to stop flowing for prolonged periods. We observed H. amphibius movements to be highly constrained to the river course with grassy floodplains being their preferred habitat. Dominant and small sub-adult males displayed year-round residency in/near river pools and had smaller home ranges compared to large sub-adults. During the dry season, large sub-adult males made significant (~15 km) upstream movements. The larger home range size of large sub-adults can be attributed to the elevated levels of migratory and exploratory activities to limit conspecific aggression as the river dries. Our observations provide insight into how future changes in water flow may influence male H. amphibius movements and populations through density-dependent effects.

PAG neurons encode a simplified action-selective signal during aggression

SummaryWhile the ventromedial hypothalamus, ventrolateral area (VMHvl) is now well established as a critical locus for the generation of conspecific aggression, its role is complex, with populations of neurons responding during the motivational, sensory, and action phases of aggression, and also during social interactions with the opposite sex. It has been previously unclear how the brain uses this complex multidimensional signal and generates a discrete action: the attack. Here we find that the largest posterior target of the VMHvl, the lateral periaqueductal gray (lPAG) encodes a simplified attack-selective signal during aggression. Single units in the lPAG exhibit greater selectivity for the attack action during aggression than VMHvl neurons and a subpopulation of neurons in the PAG exhibit short-latency, time-locked spiking relative to the activity of jaw muscles for biting during attack. In addition, channelrhodopsin assisted circuit mapping reveals a preferential projection from VMHvl glutamatergic cells to lPAG glutamatergic cells. Using projection-specific fiber photometry, we find that this excitatory projection conveys male-biased signals from the VMHvl to downstream glutamatergic PAG neurons that integrate ongoing male-related activity over several seconds, which suggests that action-selectivity is generated by a combination of both pre and postsynaptic filtering mechanisms.

The gut microbiome correlates with conspecific aggression in a small population of rescued dogs(Canis familiaris)

Aggression is a serious behavioral disorder in domestic dogs that endangers both dogs and humans. The underlying causes of canine aggression are poorly resolved and require illumination to ensure effective therapy. Recent research links the compositional diversity of the gut microbiome to behavioral and psychological regulation in other mammals, such as mice and humans. Given these observations, we hypothesized that the composition of the canine gut microbiome could associate with aggression. We analyzed fecal microbiome samples collected from a small population of pit bull type dogs seized from a dogfighting organization. This population included 21 dogs that displayed conspecific aggressive behaviors and 10 that did not. Beta-diversity analyses support an association between gut microbiome structure and dog aggression. Additionally, we used a phylogenetic approach to resolve specific clades of gut bacteria that stratify aggressive and non-aggressive dogs, including clades withinLactobacillus,Dorea,Blautia,Turicibacter,andBacteroides. Several of these taxa have been implicated in modulating mammalian behavior as well as gastrointestinal disease states. Although sample size limits this study, our findings indicate that gut microorganisms are linked to dog aggression and point to an aggression-associated physiological state that interacts with the gut microbiome. These results also indicate that the gut microbiome may be useful for diagnosing aggressive behaviors prior to their manifestation and potentially discerning cryptic etiologies of aggression.

The gut microbiome correlates with conspecific aggression in a small population of rescued dogs (Canis familiaris)

Aggression is a serious behavioral disorder in domestic dogs that endangers both dogs and humans. The underlying causes of canine aggression are poorly resolved and require illumination to ensure effective therapy. Recent research links the compositional diversity of the gut microbiome to behavioral and psychological regulation in other mammals, such as mice and humans. Given these observations, we hypothesized that the composition of the canine gut microbiome could associate with aggression. We analyzed fecal microbiome samples collected from a small population of pit bull type dogs seized from a dogfighting organization. This population included twenty-one dogs that displayed conspecific aggressive behaviors and ten that did not. Beta-diversity analyses support an association between gut microbiome structure and dog aggression. Additionally, we used a phylogenetic approach to resolve specific clades of gut bacteria that stratify aggressive and non-aggressive dogs, including clades within Lactobacillus, Dorea, Blautia, Turicibacter, and Bacteroides. Several of these taxa have been implicated in modulating mammalian behavior as well as gastrointestinal disease states. Although sample size limits this study, our findings indicate that gut microorganisms are linked to dog aggression and point to an aggression-associated physiological state that interacts with the gut microbiome. These results also indicate that the gut microbiome may be useful for diagnosing aggressive behaviors prior to their manifestation and potentially discerning cryptic etiologies of aggression.