Effects of experience on the development of social behaviour of house-dwelling bats

This study aims at clarifying the mechanisms underlying the formation and maintenance of stable social units in bats (Chiroptera), a characteristic shared by most species of this group of mammals, by investigating the effects of the early social environment, i.e. pursuing the hypothesis that imprinting-like influences on the development of social behaviour exist and may have a profound impact on the social lives of bats. First I present an overview on bats' social behaviour and systems: these mammals comprise a high number of species and thus constitute an excellent group for testing general hypotheses about evolution and development of social behaviour. Bat social systems in fact range from solitary species to others aggregating in conspicuous groups of up to millions individuals. Such complexity leads to a variety of social behaviours rarely found in other taxonomic groups: there is increasing evidence that bats are able of cooperative social behaviours such as allogrooming, communal nursing, group hunting and social learning, all interactions that require high-level cognitive skills. Investigating such a complex system needs a multi-disciplinary approach, fundamental for disentangling the mechanisms through which bat sociality develops. I performed a series of experiments and used classical ethological and statistical methods (ethogram composition, general linear models) together with social network analysis (SNA), developing the analyses of social interactions on an individual-based approach. Experiment 1 deals with the ability of bats to modulate their behaviour (e.g. aggressiveness) according to intrinsic (e.g. age, sex) and extrinsic (familiarity) factors during a social interaction. I performed dyadic arena-encounters where two bats per test were allowed to freely interact. I recorded aggressive and affiliative behaviours and measured the degree of affiliation towards familiar and unfamiliar individuals of captive European free-tailed bats 9 (Tadarida teniotis). By testing individuals from different captive colonies and of different age, I measured the effects of familiarity, sex and age on the aggressive behaviour of this species, using aggressiveness as a proxy for xenophobia. I found significant effects of all the selected factors upon the degree of affiliation among individuals: familiar bats were more prone to perform affiliative behaviours, behaving xenophobically towards non-group members. This xenophobic attitude was lower in females and almost null towards juveniles. These results indicate that adult bats' behaviour is influenced by previous social experiences, also suggesting that social bonds formed inside colonies are long lasting regardless of genetic relatedness existing between individuals. With experiment 2 I investigate the mechanisms leading to the formation of social subunits in groups bats, using Pipistrellus kuhlii as a model species. By manipulating the early social environment of young bats and describing their pattern of association inside artificial roost as well as measuring their rates of interaction, I demonstrate that spatial proximity inside roosts promotes social cohesion. These associations are maintained by bats throughout adulthood by means of cooperative behaviours such as allogrooming and social thermoregulation. Both classical approach and social network analysis of interacting bats indicate that physical contacts and cooperative behaviours among bats inside a colony are non-random and are more frequently performed between individuals that already had contacts at a very young age. Following the same approach and techniques of Experiment 2, with Experiment 3 I test the hypothesis that the same mechanisms that produce group cohesion inside roosts can lead to the formation of multi-specific associations of bats. Such multi-specific groups are widespread among mammals, and in bats they are assumed to form due to eco-physiological reasons (i.e. species sharing micro-climatic requirements). I manipulated the early social environment of two species that naturally occur inside the same roosts; very young Kuhl's (P. kuhlii) and Savi's (Hypsugo savii) bats were exposed to artificial multi-specific social contacts in captivity. I demonstrate that early social experience does influence social bonding also beyond the species' boundaries. Independent young bats in fact selected previous groupmembers for social thermoregulation and reciprocal grooming, regardless of species membership. Results from all experiment clearly indicate a strong effect of early social environment on the interaction and association patterns in bats, both at short (Experiments 2-3) and long (Experiment 1) time scales, suggesting the existence of imprinting-like mechanisms. Such mechanisms lead to the formation of cryptic social subunits within bat colonies and probably enhance the cohesion of the entire social structure, with obvious and strong consequences on behavioural and ecological (e.g. demographic and epidemiological) scales

Free-ranging livestock and a diverse landscape structure increase bat foraging in mountainous landscapes

Traditional farming, where livestock is seasonally managed as free-ranging and the use of drugs is reduced or absent, may prove beneficial to biodiversity by fostering the occurrence of spatial heterogeneity, and increasing the availability of trophic resources to wildlife. Previous work indicates that the presence of cattle in lowlands leads to an increase in bat foraging activity, yet no study has addressed this topic in mountainous regions, where free-ranging livestock is still common. Here we explore the relationships between landscape structure, farming and bat activity in a mountainous agricultural area, hypothesizing that bat activity will increase in response to the presence of livestock and landscape structure and heterogeneity. We found that traditional cattle farming may have a role in influencing bat activity in mountainous agroecosystems, yet its effects are evident for a limited number of species. Three pipistrelle species favoured foraging in areas subjected to cattle farming by hunting more often over cattle or fresh dung than at control sites. Free-ranging cattle thus provide profitable foraging opportunities for bats in mountainous landscapes, which remarks the importance of traditional farming activities in sustaining biodiversity. Cattle might also benefit from bat foraging activity if this leads to suppression of bloodsucking pests

One strategy does not fit all: determinants of urban adaptation in mammals

Urbanisation exposes wildlife to new challenging conditions and environmental pressures. Some mammalian species have adapted to these novel environments, but it remains unclear which characteristics allow them to persist. To address this question, we identified 190 mammals regularly recorded in urban settlements worldwide, and used phylogenetic path analysis to test hypotheses regarding which behavioural, ecological and life history traits favour adaptation to urban environments for different mammalian groups. Our results show that all urban mammals produce larger litters; whereas other traits such as body size, behavioural plasticity and diet diversity were important for some but not all taxonomic groups. This variation highlights the idiosyncrasies of the urban adaptation process and likely reflects the diversity of ecological niches and roles mammals can play. Our study contributes towards a better understanding of mammal association to humans, which will ultimately allow the design of wildlife-friendly urban environments and contribute to mitigate human-wildlife conflicts

Italian red squirrels and introduced parakeets: victims or perpetrators?

This paper deals with the first records of interactions between Italian red squirrel (Sciurus vulgaris italicus) and introduced parakeets. We observed two nest predations exerted by red squirrels upon rose-ringed parakeet (Psittacula krameri) chicks in Latium, while an adult Barraband's parakeet (Polytelis swainsonii) was responsible for the death of an adult squirrel in Southern Tuscany. To assess the extent of the impact of these alien birds on the conservation of the endemic squirrel populations, further research is needed. These observations highlight the complex interactions that may arise between alien and native species, supporting that active monitoring and management of introduced populations should be a priority

A framework for prioritising present and potentially invasive mammal species for a national list

The European Union (EU) has recently adopted a regulation on invasive alien species that foresees the possibility of developing lists of species of National Concern. We developed a prioritisation process for alien mammals already established in Italy, but not yet included in the EU list (n = 6 species) and a systematic horizon-scanning procedure to obtain ranked lists for those species that are already introduced worldwide or traded in Italy (n = 213). Experts were asked to score these species, by evaluating their likelihood of establishment and spread and the magnitude of their potential impacts on biodiversity, economy, human-health and society. The manageability of each species was also evaluated, both for the proritisation and the horizon-scanning processes. We produced five lists that ranked species according to their potential spread and impacts and their manageability. These will allow policy-makers to select outputs according to a balance between risk assessment and risk management, establishing priorities for alien species management at the national level

Mammals of Italy: An annotated checklist

Checklists represent a basic tool for conservation and management of regional faunas. However, our knowledge on species composition in a territory changes over time due to species movements across borders, extinctions, introductions, as well as to new taxonomic evidence. We aimed to provide the most updated data on native and non-native species of mammals occurring, or that used to occur until recently, on the Italian political territory and seas. The checklist only includes species whose taxonomic status was explicitly agreed in the most recent peer-reviewed literature and based on the most updated taxonomic approaches. For each species, we provided the following information: scientific and common name, global and Italian range, relevant information for management and conservation (e.g. whether it is endemic, allochthonous, or listed in international regulations and red list assessments), as well as remarks on taxonomy and distribution. This new check list of Italian mammal fauna includes nine marine and 114 terrestrial species, belonging to seven orders (Erinaceomorpha, Soricomorpha, Chiroptera, Carnivora, Cetartiodactyla, Rodentia, Lagomorpha), and 28 families. Vespertilionidae represents the richest family (n=27 species), followed by Cricetidae (n=12) and Soricidae (n=11). The list includes 15–16 allocthonous species. Considering the relative small size of the country, Italy is confirmed as a hotspot of mammal diversity in Europe, hosting the highest species richness in relation to the total area

Sociality influences thermoregulation and roost switching in a forest bat using ephemeral roosts

In summer, many temperate bat species use daytime torpor, but breeding females do so less to avoid interferences with reproduction. In forest-roosting bats, deep tree cavities buffer roost microclimate from abrupt temperature oscillations and facilitate thermoregulation. Forest bats also switch roosts frequently, so thermally suitable cavities may be limiting. We tested how barbastelle bats (Barbastella barbastellus), often roosting beneath flaking bark in snags, may thermoregulate successfully despite the unstable microclimate of their preferred cavities. We assessed thermoregulation patterns of bats roosting in trees in a beech forest of central Italy. Although all bats used torpor, females were more often normothermic. Cavities were poorly insulated, but social thermoregulation probably overcomes this problem. A model incorporating the presence of roost mates and group size explained thermoregulation patterns better than others based, respectively, on the location and structural characteristics of tree roosts and cavities, weather, or sex, reproductive or body condition. Homeothermy was recorded for all subjects, including nonreproductive females: This probably ensures availability of a warm roosting environment for nonvolant juveniles. Homeothermy may also represent a lifesaver for bats roosting beneath loose bark, very exposed to predators, because homeothermic bats may react quickly in case of emergency. We also found that barbastelle bats maintain group cohesion when switching roosts: This may accelerate roost occupation at the end of a night, quickly securing a stable microclimate in the newly occupied cavity. Overall, both thermoregulation and roost-switching patterns were satisfactorily explained as adaptations to a structurally and thermally labile roosting environment

Adverse effects of artificial illumination on bat drinking activity

Artificial illumination at night (ALAN) alters many aspects of animal behaviour. Commuting and foraging bats have been found to be affected by ALAN, but no study has yet addressed the impact of lighting on drinking activity, despite its critical importance for bats. We experimentally illuminated cattle troughs used by drinking bats at four forest sites in Italy, and compared drinking activity and foraging activity under lit and dark conditions. We predicted that (1) the number of bat species and drinking events will be lower under illumination and (2) forest bat species will be more affected than edge specialists. We recorded 2549 drinking events from 12 species or species groups, most of which decreased drinking activity under illumination. The effects of ALAN on drinking were stronger than on foraging. Forest species never drank when the light was on. Edge-foraging species reduced drinking activity while also increasing foraging under lit conditions. We highlight a previously overlooked negative effect of ALAN on bats, whose implications may be locally catastrophic. Given the importance of water sites for both bat foraging and drinking, their illumination should be forbidden, appropriately mitigated or, if necessary, compensated for with the creation of alternative drinking sites

Priority questions for biodiversity conservation in the Mediterranean biome: Heterogeneous perspectives across continents and stakeholders

International audienceThe identification of research questions with high relevance for biodiversity conservation is an important step towards designing more effective policies and management actions, and to better allocate funding among alternative conservation options. However, the identification of priority questions may be influenced by regional differences in biodiversity threats and social contexts, and to variations in the perceptions and interests of different stakeholders. Here we describe the results of a prioritization exercise involving six types of stakeholders from the Mediterranean biome, which includes several biodiversity hotspots spread across five regions of the planet (Europe, Africa, North and South America, and Australia). We found great heterogeneity across regions and stakeholder types in the priority topics identified and disagreement among the priorities of research scientists and other stakeholders. However, governance, climate change, and public participation issues were key topics in most regions. We conclude that the identification of research priorities should be targeted in a way that integrates the spectrum of stakeholder interests, potential funding sources and regional needs, and that further development of interdisciplinary studies is required. The key questions identified here provide a basis to identify priorities for research funding aligned with biodiversity conservation needs in this biome