An investigation of the olfactory and multi-modal communication of African lions (Panthera leo) in the Okavango Delta, Botswana

Communication is a crucial mechanism at the basis of animal social behaviour and likely to be of central importance in facilitating the evolution of complex animal societies. This thesis aims to expand our knowledge of the olfactory, vocal and multi-modal communication of wild African lions. Much of our understanding of lion behaviour originates from studies in East Africa, yet the ancestral lion may have been a wetland specialist in habitats such as the Okavango Delta. Here I first employ an established playback design to test whether lions can determine the number of conspecifics calling in large vocal choruses, demonstrating that the upper limit for lions to assess the number of simultaneous callers is three, matching the ability of humans performing a similar task. I then use a novel playback experiment to demonstrate that lions are capable of cross-modal processing of information on individual identity; an ability originally thought to be unique to humans and not previously demonstrated in wild animal populations. Next, I provide a novel and detailed investigation into the olfactory communication of lions. First I analyse the scent-marking of lions and the responses of group members to marks, and demonstrate that chemical signals may play an important role in the social lives of prides. I then use a scent presentation experiment to test the function of urinary scent-marks in communication within and between prides, determining that lion urine signals the social group and sex of the depositor and may be important for sexual assessment and territory defence. Overall this thesis significantly advances our knowledge of the vocal and olfactory communication of African lions, and provides the first evidence that lions are capable of cross-modal individual recognition during communication between conspecifics. Together these results highlight that olfactory and multi-modal communication are important for lions, despite being previously overlooked

Cross-modal individual recognition in wild African lions

Individual recognition is considered to have been fundamental in the evolution of complex social systems and is thought to be a widespread ability throughout the animal kingdom. Although robust evidence for individual recognition remains limited, recent experimental paradigms that examine cross-modal processing have demonstrated individual recognition in a range of captive non-human animals. It is now highly relevant to test whether cross-modal individual recognition exists within wild populations and thus examine how it is employed during natural social interactions. We address this question by testing audio–visual cross-modal individual recognition in wild African lions (Panthera leo) using an expectancy-violation paradigm. When presented with a scenario where the playback of a loud-call (roaring) broadcast from behind a visual block is incongruent with the conspecific previously seen there, subjects responded more strongly than during the congruent scenario where the call and individual matched. These findings suggest that lions are capable of audio–visual cross-modal individual recognition and provide a useful method for studying this ability in wild populations

Seasonal patterns in habitat use by the harvest mouse (Micromys minutus) and other small mammals

The ecology of the harvest mouse (Micromys minutus) is poorly understood, partly because it is a difficult species to monitor. It is commonly associated with reedbeds, where evidence suggests that it experiences strong seasonal fluctuations in abundance. However, it is unknown whether these fluctuations are caused by real changes in population size, or by movement between habitats. This study investigated seasonal changes in population size and habitat use by harvest mice, and other small mammal species, by trapping the reedbed and three associated habitat types: woodland, pasture and arable land. A sampling effort of 9887 trap bouts across nine months, resulted in 70 captures of harvest mice, as well as wood mice (N = 1022), bank voles (N = 252), field voles (N = 9), common shrews (N = 86) and pygmy shrews (N = 7). The reedbed was the habitat with the most captures and highest diversity. Harvest mice were caught exclusively in the reedbed at the beginning of autumn. Wood mice and bank voles experienced fluctuations in population numbers and wood mice also showed seasonal variation in habitat use. Our study supports the idea that harvest mice undergo extreme seasonal fluctuations in abundance in reedbeds, but these do not appear to be related to changes in habitat use

Spatial and seasonal patterns of communal latrine use by spotted hyenas (Crocuta crocuta) reflect a seasonal resource defense strategy

© 2020, Springer-Verlag GmbH Germany, part of Springer Nature. Abstract: Communal marking sites, or latrines, appear to play an important role in intraspecific communication and social dynamics in a wide range of mammal species. The spatial distribution of latrines can provide clues to their function and has been well documented in a number of species. Latrine use may vary considerably through time, however, and a more comprehensive approach to their study that considers spatial and seasonal patterns of use is required to understand more fully the costs and benefits of latrine use, and hence their adaptive significance. This study investigated spatial and seasonal patterns of latrine use by spotted hyena (Crocuta crocuta) in northern Botswana, examining their potential role in resource defense. Latrine characteristics and hyena activity were monitored to test the influence of season and location (relative to clan territories and roads) on latrine use. We conducted monthly scat counts (at 78 latrines) and continuously recorded hyena visitation (to 50 latrines) in five clan home ranges, demonstrating clear seasonal patterns in latrine use. Latrines were smaller in the wet season (November-March), resulting from fewer visits by hyenas, reduced scat accumulation, and the seasonal activity of coprophagous beetles. We speculate that such a seasonal pattern may be driven by reduced competition for food during the wet season. Latrines located within core clan areas were no larger or more frequently used than those in home-range boundary areas, but hyenas did preferentially place latrines alongside roads and were more likely to reuse road-side latrines in subsequent years. This pattern was not due to observer detection bias and adds to the growing body of literature on the impact that roads and other anthropogenic features have on the communication and movement ecology of wild animals. Significance statement: Although most mammals use communal marking sites, very little is known about their function and detailed patterns of use in many species. We investigated latrine use in spotted hyena (Crocuta crocuta) and describe spatial and temporal marking patterns that are consistent with optimizing scent longevity and detection. Spatially, hyenas preferentially located latrines along the edge of man-made vehicle tracks, which may increase signal detection and transmission. Seasonal marking patterns suggest that hyenas optimize their communication by concentrating activity in the dry season, thereby avoiding the disruptive effects of coprophagous dung beetles and rain, and focusing activity during periods when food resources are expected to be scarcer. These results demonstrate seasonal and spatial optimization of communication, including in response to novel anthropogenic features in the environment such as roads, advancing our understanding of communication strategies in mammals more broadly

Data from: Cross-modal individual recognition in wild African lions

Individual recognition is considered to have been fundamental in the evolution of complex social systems and is thought to be a widespread ability throughout the animal kingdom. Although robust evidence for individual recognition remains limited, recent experimental paradigms that examine cross-modal processing have demonstrated individual recognition in a range of captive non-human animals. It is now highly relevant to test whether cross-modal individual recognition exists within wild populations and thus examine how it is employed during natural social interactions. We address this question by testing audio–visual cross-modal individual recognition in wild African lions (Panthera leo) using an expectancy-violation paradigm. When presented with a scenario where the playback of a loud-call (roaring) broadcast from behind a visual block is incongruent with the conspecific previously seen there, subjects responded more strongly than during the congruent scenario where the call and individual matched. These findings suggest that lions are capable of audio–visual cross-modal individual recognition and provide a useful method for studying this ability in wild populations

Gilfillan et al. Raw Data

Raw data for the response of lions to the cross-modal playback experiments

Efficacy and safety of methionine aminopeptidase 2 inhibition in type 2 diabetes: a randomised, placebo-controlled clinical trial

AIMS/HYPOTHESIS: This multicentre randomised double-blind placebo-controlled clinical trial assessed the efficacy and safety of a methionine aminopeptidase 2 (MetAP2) inhibitor, beloranib, in individuals with obesity (BMI ≥30 kg/m2) and type 2 diabetes (HbA1c 53-97 mmol/mol [7-11%] and fasting glucos