Bat mating systems-A review and recategorisation

Mating systems, influenced by the social and ecological environment and individual attributes, are fundamental components of animal social organisation, impacting behaviour, animal distribution, ecosystem processes, individual reproductive success, and population dynamics. Bats are of particular interest for studies of mating systems as they are thought to exhibit a greater diversity in mating systems than any other mammalian order, and thus make great models for improving our fundamental understanding of causes and consequences of social organisation. Here, we review the current knowledge of bat mating systems. Our analyses show that research on bat mating systems has not kept pace with research on bats in general and that traditional typologies do not accommodate the mating system of several species. Therefore, we propose an alternative, functional framework to categorise mating systems of bats and by extension of other taxa. We argue that mating systems can be classified according to a male reproductive skew continuum, with an increasing skew from monogamy to true lekking. We include an additional category of lek-like mating system along the continuum to account for previous trans-categorical cases that have the appearance of resource defence but are functionally akin to a lek. The new framework has a total of seven categories: promiscuity, monogamy, female defence polygyny, resource defence polygyny, a lek-like mating system, exploded classical lek, and clustered classical lek. Applying this framework to bats reveals that lek mating systems are more prevalent in bats than previously recognised. It is our aim that this review and the proposed framework provide a greater understanding of bat mating systems particularly and provoke research into the factors that shape mating systems across animal taxa more generally.

Sex differences and individual variability in the captive Jamaican fruit bat (Artibeus jamaicensis) intestinal microbiome and metabolome

The intestinal microbiome plays an important role in mammalian health, disease, and immune function. In light of this function, recent studies have aimed to characterize the microbiomes of various bat species, which are noteworthy for their roles as reservoir hosts for several viruses known to be highly pathogenic in other mammals. Despite ongoing bat microbiome research, its role in immune function and disease, especially the effects of changes in the microbiome on host health, remains nebulous. Here, we describe a novel methodology to investigate the intestinal microbiome of captive Jamaican fruit bats (Artibeus jamaicensis). We observed a high degree of individual variation in addition to sex- and cohort-linked differences. The intestinal microbiome was correlated with intestinal metabolite composition, possibly contributing to differences in immune status. This work provides a basis for future infection and field studies to examine in detail the role of the intestinal microbiome in antiviral immunity.

Effects of Host Species Identity and Diet on the Biodiversity of the Microbiota in Puerto Rican Bats

Microbiota perform vital functions for their mammalian hosts, making them potential drivers of host evolution. Understanding effects of environmental factors and host characteristics on the composition and biodiversity of the microbiota may provide novel insights into the origin and maintenance of these symbiotic relationships. Our goals were to (1) characterize biodiversity of oral and rectal microbiota in bats from Puerto Rico; and (2) determine the effects of geographic location and host characteristics on that biodiversity. We collected bats and their microbiota from three sites, and used four metrics (species richness, Shannon diversity, Camargo evenness, Berger-Parker dominance) to characterize biodiversity. We quantified the relative importance of site, host sex, host species-identity, and host foraging-guild on biodiversity of the microbiota. Microbe biodiversity was highly variable among conspecifics. Geographical location exhibited consistent effects, whereas host sex did not. Within each host guild, host species exhibited consistent differences in biodiversity of oral microbiota and of rectal microbiota. Oral microbe biodiversity was indistinguishable between guilds, whereas rectal microbe biodiversity was significantly greater in carnivores than in herbivores. The high intraspecific and spatial variation in microbe biodiversity necessitate a relatively large number of samples to statistically isolate the effects of environmental or host characteristics on the microbiota. Species-specific biodiversity of oral microbiota suggests these communities are structured by direct interactions with the host immune system via epithelial receptors. In contrast, the number of microbial taxa that a host gut supports may be driven by host diet-diversity or composition.

The masked seducers: Lek courtship behavior in the wrinkle-faced bat Centurio senex (Phyllostomidae)

Centurio senex is an iconic bat characterized by a facial morphology deviating far from all other New World Leaf Nosed Bats (Phyllostomidae). The species has a bizarrely wrinkled face and lacks the characteristic nose leaf. Throughout its distribution from Mexico to Northern South America the species is most of the time rarely captured and only scarce information on its behavior and natural history is available. Centurio senex is frugivorous and one of the few bats documented to consume also hard seeds. Interestingly, the species shows a distinct sexual dimorphism: Adult males have more pronounced facial wrinkles than females and a fold of skin under the chin that can be raised in style of a face mask. We report the first observations on echolocation and mating behavior of Centurio senex, including synchronized audio and video recordings from an aggregation of males in Costa Rica. Over a period of 6 weeks we located a total of 53 perches, where during the first half of the night males were hanging with raised facial masks at a mean height of 2.35 m. Most of the time, the males moved just their wing tips, and spontaneously vocalized in the ultrasound range. Approaches of other individuals resulted in the perching male beating its wings and emitting a very loud, low frequency whistling call. Following such an encounter we recorded a copulation event. The observed aggregation of adult C. senex males is consistent with lek courtship, a behavior described from only few other bat species.

Notas sobre el uso de ecosistemas subterráneos por murciélagos en el Parque Nacional Tingo María, Huánuco, Perú

En el Perú existe poca información sobre la biodiversidad de los ecosistemas subterráneos, particularmente de las cuevas. En este trabajo registré qué especies de murciélagos habitan las cuevas del Parque Nacional Tingo María (PNTM) y cómo se distribuyen dentro de las mismas categorizándolas en tipos de percha. Evalué seis formaciones rocosas en el PNTM en los años 2015 y 2017. Se usaron redes de niebla y de mano para capturar a los murciélagos. En total registre 16 especies de murciélagos pertenecientes a las familias Phyllostomidae, Emballonuridae y Mormoopidae. En la cueva de “Las lechuzas” encontré el mayor número de especies (10). Categoricé tres tipos de percha usados por los murciélagos dentro de las cuevas: (I) pequeñas bóvedas formadas como depresiones en el techo, (II) espacios angostos en medio de las estalactitas, (III) cavidades amplias entre las estalactitas y la pared en forma de campana. Las cuevas del PNTM contribuyen a la persistencia local de los murciélagos proveyéndoles de refugios, y existe la necesidad de conocer sobre los aspectos ecológicos y la importancia funcional de los murciélagos dentro de estas cuevas.

SURGICAL ORCHIECTOMY IN FRUIT BATS-DESCRIPTION OF TWO TECHNIQUES IN THE RUWENZORI LONG-HAIRED FRUIT BAT (ROUSETTUS LANOSUS) AND THE JAMAICAN FRUIT-EATING BAT (ARTIBEUS JAMAICENSIS)

Contraception is needed to prevent overpopulation and inbreeding in highly fecund captive bat colonies. Reports on surgical contraception in bats are limited. The objective of this study was to describe surgical castration techniques in a megachiropteran and a microchiropteran fruit bat species. Open orchiectomy by transfixing ligation of the spermatic cord was performed in 14 Ruwenzori long-haired fruit bats (Rousettus lanosus) (RL-LIG), and orchiectomy with radiosurgery alone was performed in 125 Jamaican fruit-eating bats (Artibeus jamaicensis) (AJ-RS) and one Ruwenzori bat (RL-RS). The surgical techniques were not compared in different species with the exception of the one Ruwenzori bat operated with RS. Anesthesia was induced and maintained with isoflurane in oxygen via facemask. Preoperatively, all bats received butorphanol and subcutaneous fluids. Meloxicam was administered postoperatively for the RL-LIG. For the RL-LIG, anesthesia lasted 49 ± 15 min (mean ± SD) with a total surgery time of 26 ± 12 min. In comparison, the RS was considerably shorter, lasting 10 ± 3 min for anesthesia and 5 ± 2 min for surgery. Complications were rare, with a morbidity rate of 6.7% with the RL-LIG (prolonged recovery [n = 1]) and of 4.8% with the RS (dyspnea [n = 3], hemorrhage [n = 2], and prolonged recovery [n = 1]). One of the cases of hemorrhage was in the single Ruwenzori bat castrated using the RS technique. Mortality rate was 1.6% (n = 2) with the RS. No mortality occurred with the RL-LIG. In conclusion, using radiosurgery alone appears to be a safe and rapid surgical technique in smaller species of fruit bats. For larger species, such as the Ruwenzori fruit bats, ligation or use of an advanced vessel sealing system is recommended.

A framework for conceptualizing dimensions of social organization in mammals

Mammalian societies represent many different types of social systems. While some aspects of social systems have been extensively studied, there is little consensus on how to conceptualize social organization across species. Here, we present a framework describing eight dimensions of social organization to capture its diversity across mammalian societies. The framework uses simple information that is clearly separated from the three other aspects of social systems: social structure, care system, and mating system. By applying our framework across 208 species of all mammalian taxa, we find a rich multidimensional landscape of social organization. Correlation analysis reveals that the dimensions have relatively high independence, suggesting that social systems are able to evolve different aspects of social behavior without being tied to particular traits. Applying a clustering algorithm allows us to identify the relative importance of key dimensions on patterns of social organization. Finally, mapping mating system onto these clusters shows that social organization represents a distinct aspect of social systems. In the future, this framework will aid reporting on important aspects of natural history in species and facilitate comparative analyses, which ultimately will provide the ability to generate new insights into the primary drivers of social patterns and evolution of sociality.

Social interactions, roost usage and notes on the breeding system of the chocolate wattled bat (Chalinolobus morio) in south-east Queensland, Australia

Little is known about the social behaviour of roosting insectivorous bats in Australia. Interactions between individuals and movements between multiple roosts at a building maternity site of the chocolate wattled bat (Chalinolobus morio) were examined using video observation and Passive Integrated Transponder (PIT) tagging, respectively. Bats of both sexes were seen to allogroom, which involved pairs of individuals simultaneously grooming each other around the face. This is the first occurrence of allogrooming reported between male vespertilionids, globally. In total, 366 bats were PIT tagged and analysis of movements revealed that bats exhibited a fission–fusion pattern of roost usage with sufficient switching among nearby roosts, such that all individuals were potentially able to associate and interact over a period of 150–200 days. Rates of roost fidelity varied markedly from 1 to 7.2 days of continuous occupancy of roosts, with females exhibiting slightly higher overall levels of fidelity over the nine-month monitoring period. The information gained from this study, when combined with results from other research, provides a sufficient basis for the description of the apparent breeding system for this species, where both males and females at the summer maternity roost are natally philopatric and mating takes place over winter in an expanded gene pool, comprising individuals that have dispersed from multiple summer maternity roosts.

New records of Niceforo's big-eared bat, Trinycterisnicefori (Sanborn, 1949) (Chiroptera, Phyllostomidae), from the state of Maranhão, Brazil

Niceforo's big-eared bat, Trinycterisnicefori (Sanborn, 1949), is a monotypic species which has been recorded in a number of Brazilian states, but has a disjunct distribution in this country. This study presents the first record of T.nicefori in the Brazilian state of Maranhão. The specimens were collected in the municipalities of Godofredo Viana and Cândido Mendes, in fragments of the Amazon forest. One male (forearm: 38.00 mm, weight: 6 g) and one female (39.68 mm, 8 g) specimens were collected. The specimens presented chestnut-colored fur, and a chin with a pair of dermal pads arranged in a V-shape, without a central papilla. The COI gene sequences were plotted in the BOLD Systems platform, which confirmed the morphological identification of the species, with a 99.1% similarity in the male, and 99.4% in the female to existing sequences. This record extends the known distribution of T.nicefori in Brazil by approximately 310 km to the most eastern part of the Amazon Biome.

Advances on the group composition, mating system, roosting and flight behaviour of the European free-tailed bat (Tadarida teniotis)

We investigated a large colony of European free-tailed bats (Tadarida teniotis) in Spain, using a combination of capture-mark-recapture data and direct observations. Its social and reproductive organisation is complex and the mating system fits a “resource defence polygyny” model. In spring and autumn, aggressive interactions in flight, defence of roosts and mating songs of males to attract females occurred. According to our results, T. teniotis is organised in “harems” consisting of a dominant male and a variable number of females. In addition the sexual cycle displayed a bimodal reproductive pattern (this is unique and remarkable for European bats). The bimodal pattern coincided with peaks in food availability (moths) at high altitudes. Presumably, roost-guarding activities (patrolling, advertising…) make males less prone to move away (e.g. at higher altitudes and longer distances) from roosts, resulting in differences in prey selection and in altitudinal segregation between sexes. This provides a plausible explanation for the differences in diet (predation of more sedentary vs. high-flying migratory moths) between males and females that has been found in published studies.

From resource to female defence: the impact of roosting ecology on a bat's mating strategy

With their extraordinary species richness and diversity in ecological traits and social systems, bats are a promising taxon for testing socio-ecological hypotheses in order to get new insights into the evolution of animal social systems. Regarding its roosting habits, proboscis bats form an extreme by occupying sites which are usually completely exposed to daylight (e.g. tree trunks, vines or rocks). This is accompanied by morphological and behavioural adaptations to remain cryptic in exposed day roosts. With long-term behavioural observations and genetic parentage analyses of individually marked proboscis bats, we assessed its social dispersion and male mating strategy during day and night. Our results reveal nocturnal male territoriality-a strategy which most closely resembles a resource-defence polygyny that is frequent also in other tropical bats. Its contrasting clumped social dispersion during the day is likely to be the result of strong selection for crypsis in exposed roosts and is accompanied by direct female defence in addition to male territoriality. To the best of our knowledge, such contrasting male mating strategies within a single day-night cycle have not been described in a vertebrate species so far and illustrate a possible evolutionary trajectory from resource-defence to female-defence strategy by small ecologically driven evolutionary steps.

The orbitofacial glands of bats: an investigation of the potential correlation of gland structure with social organization

The facial glands of bats are modified skin glands, whereas there are up to three different orbital glands: Harderian, lacrimal, and Meibomian glands. Scattered studies have described the lacrimal and Meibomian glands in a handful of bat species, but there is as yet no description of a Harderian gland in bats. In this study we examined serial sections of orbitofacial glands in eight families of bats. Much variation amongst species was observed, with few phylogenetic patterns emerging. Enlarged facial glands, either sudoriparous (five genera) or sebaceous (vespertilionids only) were observed. Meibomian and lacrimal glands were present in most species examined (except Antrozous), though the relative level of development varied. Two types of anterior orbital glands were distinguished: the Harderian gland (tubulo-acinar: observed in Rousettus, Atribeus, Desmodus and Miniopterus) and caruncular (sebaceous: observed in Eptesicus and Dieamus). The relative development of the nasolacrimal duct and the vomeronasal organ did not appear to be correlated with the development of any of the exocrine glands examined. There does, however, appear to be a correlation between the presence of at least one well developed exocrine gland and the level of communality and known olfactory acuity, best documented in Artibeus, Desmodus, and Miniopterus.

Fauna de morcegos em remanescentes urbanos de Cerrado em Campo Grande, Mato Grosso do Sul

Campo Grande é a maior cidade do Estado de Mato Grosso do Sul, localizada no domínio do Cerrado, um hotspot de biodiversidade. A fauna de morcegos urbanos tem sido pouco estudada no Brasil, principalmente em cidades na região do Cerrado. O principal objetivo aqui é descrever a composição, a riqueza e a diversidade da fauna de morcegos em remanescentes de Cerrado na região urbana de Campo Grande. Amostragens de morcegos foram feitas entre março e agosto de 2009 em oito parques urbanos com auxílio de redes-de-neblina. Em cada local, exceto um, foi realizada uma noite de amostragem por mês; ao todo foram 47 noites. A cada noite, seis redes de 2,6 x 12 m foram mantidas abertas por seis horas a partir do ocaso; o esforço total de captura foi de 52.790,4 m²/h. Foram capturados 701 morcegos pertencentes a 14 espécies, das quais 12 foram filostomídeos (98,6% das capturas). Artibeus lituratus foi a espécie dominante, semelhante ao reportado para outras regiões urbanas no Brasil. Artibeus planirostris foi a segunda espécie mais abundante em Campo Grande, característica incomum em outras comunidades urbanas de morcegos. Chiroderma doriae, C. villosum, Phyllostomus hastatus e Platyrrhinus helleri foram raras, e registradas pela primeira vez em Campo Grande. Somados outros estudos, 24 espécies de morcegos foram encontradas em Campo Grande, valor alto dentre as cidades nos domínios do Cerrado. A diversidade (H' = 1,65) de morcegos em Campo Grande também foi maior que a reportada para outras cidades em regiões de Cerrado ou Mata Atlântica. A ampla presença de parques florestados na zona urbana pode explicar, em parte, a grande riqueza e diversidade de morcegos na cidade de Campo Grande.

Pupal deposition and ecology of bat flies (Diptera: Streblidae): Trichobius sp. (caecus group) in a Mexican cave habitat

We studied the deposition of pupae of the winged bat fly Trichobius sp. (caecus group; Diptera), an ectoparasite of Natalus stramineus (Chiroptera, Natalidae), in a natural cave in Tamaulipas, Mexico. For the first time, we show a strong spatial segregation of populations of a streblid bat fly at different stages of development. Using molecular techniques we were able to match developmental stages to adults. Only 5 pupae were present in the main bat roosts. The overwhelming majority occurred exclusively in the bat flyway passages at a considerable distance from roosting bats. Pupal density corresponded positively with the average flight height of bats in the cave passage. Taken together, observations suggest that these ectoparasites must actively seek out their hosts by moving onto passing or roosting bats. The scarceness of pupae in the main roost may be dictated by environmental constraints for their development. The estimated population of viable pupae far exceeds the population of imagoes on the bats, and predation on adults by spiders is common.

Tents and harems: apparent defence of foliage roosts by tent-making bats

Palmate umbrella tents used by tent-making bats in Trinidad, West Indies, were observed in three species of Neotropical palms, Sabal mauritiiformis, Coccothrinax barbadensis and Mauritia flexuosa. Tents were most common in palm leaves that have supporting petioles angled at 50–70° above the horizontal. The shape and volume of tents is influenced mostly by leaf morphology (leaf width and leaflet length) and age of the tent. Tent-crowns varied from being heart-shaped in S. mauritiiformis, oval or round in C. barbadensis and spade-shaped in M. flexuosa. Leaves in which tents were constructed were most often beneath overhanging vegetation, and were generally free of vegetation below, allowing bats to enter and depart from tents without being impeded by the clutter of adjacent vegetation.

Singles and small apparent harem groups of two bat species, Artibeus jamaicensis and Uroderma bilobatum, were captured and observed in tents made from the leaves of S. mauritiiformis and C. barbadensis. No bats were observed in tents constructed in leaves of M. flexuosa. The apparent harem social organization in these and other tent-making bat species suggests that leaves modified into tents may provide critical and defendable resources that promote the evolution of polygyny. This hypothesis is based on the observed patchy distribution of suitable palm trees, the inappropriateness of many palm leaves as potential tents and the resultant architecture provided by palmate umbrella tents. We suggest that tent-making is an adult male behaviour.

Male dominance, paternity, and relatedness in the Jamaican fruit-eating bat (Artibeus jamaicensis)

We analysed variation at 14 nuclear microsatellite loci to assess the genetic structure, relatedness, and paternity of polygynous Jamaican fruit-eating bats. A total of 84 adults captured in two caves exhibited little genetic differentiation between caves (FST = 0.008). Average relatedness among adult females in 10 harem groups was very low (R = 0.014 +/- 0.011), providing no evidence of harem structure. Dominant and subordinate males shared paternity in large groups, while dominant and satellite males shared paternity in smaller groups. However, our results suggest that male rank influences paternity. Dominant males fathered 69% of 40 offspring, followed by satellite (22%) and subordinate males (9%). Overall adult male bats are not closely related, however, in large harem groups we found that subordinate and dominant males exhibited relatedness values consistent with a father-offspring relationship. Because dominant and subordinate males also sired all the pups in large groups, we propose that their association provides inclusive fitness to them.