Marta B. Manser

Prey can adjust their behaviour to perceived predation risk, which may induce non-consumptive fitness effects. However, quantifying perceived risk in field studies remains challenging as anti-predator behaviours often integrate multiple processes such as encounter probability and detection capacity. Partitioning prey responses into sub-processes may therefore provide novel insights on predation risk perception. To this end, we decomposed meerkat ( Suricata suricatta ) alarm-calling behaviour into threat discrimination, and response escalation. Using 23 years of data from a wild population in the Kalahari, we evaluated the context-dependence of both components in relation to landscape features, and group composition. We defined threat discrimination as the probability to emit an alarm call at predators (eagles) relative to non-predators (vultures) and response escalation as the strength and intensity of the ensuing collective reaction. We found that discrimination varied with habitat and vegetation productivity. Furthermore, larger groups and the presence of pups increased meerkat threat discrimination, but only during the dry season. Response escalation varied with habitat and group size, but pup presence only increased reaction strength. The contrasting context-dependence among the two alarm-calling components support decomposing compound behaviours rather than quantifying perceived risk from a single behaviour. Thus, we recommend future studies to use this approach, when possible, to improve inference on prey perception and responses to risk.

“Eavesdropping” on heterospecific alarm calls is common, but we are only beginning to understand the cognitive mechanisms involved. A key question is whether eavesdropping results from innate perceptual sensitivities to acoustic features that are common to the calls of diverse species, or if it is a learned behavior. Here, we used playback experiments to investigate whether wild and captive meerkats (Suricata suricatta), and wild yellow mongooses (Cynictis penicillata) respond in a functionally appropriate way, ie successfully “eavesdrop”, to heterospecific alarm calls. We tested calls from both sympatric and allopatric species to reveal whether responses were a result of learned associations between call types and their referents, or of innate perceptual sensitivities to their acoustic features. By playing back calls which signal either “aerial” or “general” predation threats, we also explored whether subjects could differentiate between the underlying function of heterospecific alarm calls. Our results show that wild meerkats and wild yellow mongooses, but not captive meerkats, were more likely to respond to the alarm calls of sympatric species. Additionally, wild, but not captive, meerkats were also more likely to flee as a response to aerial as opposed to general alarm calls. This indicates that learning likely affects the response of mongooses to heterospecific alarm calls. However, other factors are also likely to have an impact on how individuals in different populations of the same species respond to heterospecific alarm calls, such as innate perceptual sensitivities, external threats, the need to respond, and the soundscape a species is exposed to.

Physical grooming is often used to maintain social bonds in animal groups, but opportunities to groom every group member may be limited. Vocal exchanges may provide an alternative way to sustain social ties without physical proximity. To explore the link between vocal exchanges and social relationships, we examined how dominance and dyadic bond strength influence the intensity of vocal interaction in meerkats (Suricata suricatta). Focusing on “sunning calls”, socially facilitated vocalizations produced when meerkats warm themselves in the sun, we conducted experiments in which we played sunning calls to individuals and recorded their responses. Overall, subordinate individuals increased their call rate in response to dominant calls, whereas dominant receivers showed little or no change. The effect of tie strength was weak overall but varied across dyad types, tending to be negative in dominant–subordinate pairs and slightly positive among subordinates. These results support the notion that sunning calls serve a social regulatory function, possibly acting as bonding or appeasing signals primarily directed toward dominants. The asymmetry between dominant and subordinate responses highlights the strategic nature of social relationships within a despotic society. Engaging in continuous reciprocal interactions may promote tolerance and reduce conflict; thus, investing in such interactions with influential dominants would align with the “vocal grooming” function of these exchanges. Future studies that causally link vocal interactions to long-term relationship outcomes will be key to understanding how such vocal exchanges complement physical affiliation across species.

Our understanding of habitat selection in wild vertebrates has been heavily influenced by observations of preferred foraging areas. However, foraging is only one of many ways animals interact with their environment, and preferences for habitat features that support resting, breeding, and safety, along with trade-offs between these needs, remain underexplored. These trade-offs are likely to be particularly acute in complex environments where these needs are met in different locations. Using a long-term dataset of movements and life history, we examine how preferences for foraging areas and burrow sites shape space use in Kalahari meerkats ( Suricata suricatta ). Meerkats cannot dig new sleeping and breeding burrows and must use those abandoned by other species, potentially generating trade-offs in daily space use if overnight refuges are far from optimal foraging areas. We find that space use is strongly anchored by burrow location, with burrows in calcareous pans and dry riverbed (“white sand”) habitat being preferred year-round and showing lower burrow switching rates. However, white sand areas were not preferred for foraging, and yielded lower weight gains, particularly during the dry season. As a result, meerkats faced a trade-off between optimal burrow locations and productive foraging grounds, as indicated by faster, longer, and more energetically costly travel when moving through or waking up in white sands. Our results suggest that changes in the distribution or abundance of key burrow-constructing species in desert environments may have cascading effects on the many secondary burrow-using species that depend on them for survival and reproduction. More broadly, our results highlight that limited refuge availability across the landscape can impose strong ecological constraints on animals and may restrict behavioural plasticity under environmental change, particularly if productive foraging areas shift.

Background: The study of olfaction as a sensory modality has been relatively neglected in comparison to other sensory cues, particularly in wildlife research. Furthermore, the genetic basis of olfaction remains poorly understood in non-model species. Recently, receptors belonging to trace amine-associated receptor (TAAR) family have been identified, and they exhibit considerable natural diversity and copy number variations across a range of species. As such, they represent a promising avenue for exploring olfactory processes, particularly in conjunction with more established olfactory receptors. In meerkats ( Suricata suricatta ), olfaction plays a significant role in foraging, social communication and predator defence. However, no prior research has investigated the genetics of meerkat olfaction. In this study, we leveraged the extensive longitudinal dataset from the Kalahari Meerkat Project, using samples from 398 individuals alive between 1996 and 2023, to develop a high-throughput sequencing approach for assessing TAAR diversity in wild meerkats. Results: A total of nine TAAR-loci were identified in meerkats, with both copy number variations and allelic polymorphisms observed for TAAR6 and TAAR8. Two distinct paralogues of TAAR6 and eleven distinct amino acid alleles across these paralogues were identified. Additionally, three paralogues of TAAR8, containing 14 distinct amino acid alleles, were discovered. Within each paralogue of both TAAR loci, a single allele is present in almost all individuals, while additional alleles show a markedly higher degree of variability in frequency. A similar pattern emerges in the relative abundance of TAAR alleles throughout the course of the study, which spanned more than 20 years. In line with the high prevalence of specific alleles and the considerable number of synonymous nucleotide exchanges, we found evidence for multiple sites under purifying selection in TAAR6 and TAAR8. Conclusion: This is the first study to examine TAAR diversity in a cooperative breeder. Investigating the genetic basis of olfaction and inter-individual natural variation in TAAR diversity has the potential to expand the toolbox for integrative zoological research. Such insights could help elucidate the genetic underpinnings of behaviour, such as social communication, mate choice, and life-history strategies all in relation to TAAR diversity.

Theory predicts that high population density leads to more strongly connected spatial and social networks, but how local density drives individuals’ positions within their networks is unclear. This gap reduces our ability to understand and predict density-dependent processes. Here we show that density drives greater network connectedness at the scale of individuals within wild animal populations. Across 36 datasets of spatial and social behaviour in >58,000 individual animals, spanning 30 species of fish, reptiles, birds, mammals and insects, 80% of systems exhibit strong positive relationships between local density and network centrality. However, >80% of relationships are nonlinear and 75% are shallower at higher values, indicating saturating trends that probably emerge as a result of demographic and behavioural processes that counteract density’s effects. These are stronger and less saturating in spatial compared with social networks, as individuals become disproportionately spatially connected rather than socially connected at higher densities. Consequently, ecological processes that depend on spatial connections are probably more density dependent than those involving social interactions. These findings suggest fundamental scaling rules governing animal social dynamics, which could help to predict network structures in novel systems.

Responses of natural populations to climate change are driven by how multiple climatic and biotic factors affect survival and reproduction, and ultimately shape population dynamics. Yet, despite substantial progress in synthesizing the sensitivity of populations to climatic variation, comparative studies still overlook such complex interactions among drivers that generate variation in population-level metrics. Here, we use a common framework to synthesize how the joint effects of climate and biotic drivers on different vital rates impact population change, using unique long-term data from 41 species, ranging from trees to primates. We show that simultaneous effects of multiple climatic drivers exacerbate population responses to climate change, especially for fast-lived species. However, accounting for density feedbacks under climate variation buffers the effects of climate change on population dynamics. In all species considered in our analyses, such interactions between climate and density had starkly different effects depending on the age, size, or life-cycle stage of individuals, regardless of the life history of species. Our work provides the first general framework to assess how covarying effects of climate and density across a wide range of population models can impact populations of plants and animals under climate change.

Pathogen-mediated balancing selection (PMBS) drives host evolution across the tree of life. Distinguishing between the three main mechanisms underlying PMBS, that is, rare-allele advantage, fluctuating selection and heterozygote advantage, remains difficult, limiting our understanding of frequency-dependent adaptations by hosts and counter-adaptation by pathogens. Here we leverage immune genetic and disease surveillance data from over 1,500 wild meerkats ( Suricata suricatta ) to track how selection by the tuberculosis (TB)-causing Mycobacterium suricattae shaped the evolution of the meerkats’ major histocompatibility complex (MHC) over two decades. Compared with neutral genetic markers, we detect more rapid differentiation and recycling of alleles at the MHC-DRB loci, suggesting that TB imposes strong PMBS on wild meerkats. In addition, we show that meerkats carrying the MHC allele Susu-DRB*13 were initially more likely to develop clinical signs of TB, with the effect reversing over the course of the study, followed by an increase in the frequency of Susu-DRB*13. Meerkats carrying Susu-DRB*13 also showed slower progression to TB signs and longer survival once signs of TB manifested. Lifetime reproductive success reflected the resilience effect conferred by Susu-DRB*13. Based on several lines of evidence, we propose that rare-allele advantage or fluctuating selection, rather than heterozygote advantage, drive our observation in this longitudinally sampled wild mammal population.