Multifaceted DNA Metabarcoding of Guano to Uncover Multiple Classes of Ecological Data in Two Different Bat Communities

DNA contained in animal scat provides a wealth of information about the animal, and DNA metabarcoding of scat collections can provide key information about animal populations and communities. Next‐generation DNA sequencing technologies and DNA metabarcoding provide an efficient means for obtaining information available in scat samples. We used multifaceted DNA metabarcoding (MDM) of noninvasively collected bat guano pellets from a Myotis lucifugus colony on Fort Drum Military Installation, New York, USA, and from two mixed‐species bat roosts on Fort Huachuca Military Installation, Arizona, USA, to identify attributes such as bat species composition, sex ratios, diet, and the presence of pathogens and parasites. We successfully identified bat species for nearly 98% of samples from Fort Drum and 90% of samples from Fort Huachuca, and identified the sex for 84% and 67% of samples from these same locations, respectively. Species and sex identification matched expectations based on prior censuses of bat populations utilizing those roosts, though samples from some species were more or less common than anticipated within Fort Huachuca roosts. Nearly 62% of guano samples from Fort Drum contained DNA from Pseudogymnoascus destructans, where bats with wing damage from White‐nose Syndrome were commonly observed. Putative dietary items were detected in a majority of samples from insectivorous bats on Fort Drum (81%) and Fort Huachuca (63%). A minority of guano samples identified as the nectarivorous Leptonycteris yerbabuenae (28%) provided DNA sequences from putative forage plant species. Finally, DNA sequences from both putative ecto‐ and endoparasite taxa were detected in 35% and 56% of samples from Fort Drum and Fort Huachuca, respectively. This study demonstrates that the combination of noninvasive sampling, DNA metabarcoding, and sample and locus multiplexing provide a wide array of data that are otherwise difficult to obtain.

Agave flower visitation by pallid bats, Antrozous pallidus, in the Chihuahuan Desert

Pallid bats, Antrozous pallidus, despite being primarily insectivorous gleaning predators, consume nectar of the cardón cactus, Pachycereus pringlei, in the Sonoran Desert. It is unknown whether nectar feeding occurs in the Chihuahuan Desert of Texas, where pallid bats covered in pollen have been captured. We collected pollen samples from 67 pallid bats in Brewster County, Texas, United States, between April and August 2018. Pollen-covered pallid bats were captured in every month sampled. Pollen densities were three times higher on wings than on the head or ventral body. In all samples collected, the pollen was homogeneous and identified as Agave pollen. Although two species of Agave, A. havardiana and A. lechuguilla, occur in this region of Texas, linear discriminant analysis classified 701 of 723 (97%) of pollen grains analyzed as A. lechuguilla. Additional evidence from infrared video footage collected in August 2018 indicated that pallid bats became covered in A. lechuguilla pollen while consuming nectar. Pallid bats might be engaging in facultative nectarivory across their range and could be important nocturnal pollinators.

A review and reappraisal of the specific gravities of present and past multicellular organisms, with an emphasis on tetrapods

The density, or specific gravity (SG), of organisms has numerous important implications for their form, function, ecology, and other facets of beings living and dead, and it is especially necessary to apply SG values that are as accurate as practical when estimating their masses which is itself a critical aspect of living things. Yet a comprehensive review and analysis of this notable subject of anatomy has never been conducted and published. This is such an effort, being as extensive as possible with the data on hand, bolstered by some additional observations, and new work focusing on extinct animals who densities are least unknown: pterosaurs and dinosaurs with extensive pneumatic complexes, including the most sophisticated effort to date for a sauropod. Often difficult to determine even via direct observation, techniques for obtaining the best possible SG data are explained and utilized, including observations of floating animals. Neutral specific gravity (NSG) is proposed as the most important value for tetrapods with respiratory tracts of fluctuating volume. SGs of organisms range from 0.08 to 2.6, plant tissues from 0.08 to 1.39, and vertebrates from about 0.75 (some giant pterosaurs) to 1.2 (those with heavy armor and/or skeletons). Tetrapod NSGs tend to be somewhat higher than widely thought, especially those theropod and sauropod dinosaurs and pterosaurs with air-sacs because respiratory system volume is usually measured at maximum inhalation in birds. Also discussed is evidence that the ratio of the mass of skeletons relative to total body mass has not been properly assayed in the past.

Spatiotemporal and demographic variation in the diet of New Zealand lesser short-tailed bats (Mystacina tuberculata)

Variation in the diet of generalist insectivores can be affected by site-specific traits including weather, habitat, and season, as well as demographic traits such as reproductive status and age. We used molecular methods to compare diets of three distinct New Zealand populations of lesser short-tailed bats, Mystacina tuberculata. Summer diets were compared between a southern cold-temperate (Eglinton) and a northern population (Puroera). Winter diets were compared between Pureora and a subtropical offshore island population (Hauturu). This also permitted seasonal diet comparisons within the Pureora population. Lepidoptera and Diptera accounted for >80% of MOTUs identified from fecal matter at each site/season. The proportion of orders represented within prey and the Simpson diversity index, differed between sites and seasons within the Pureora population. For the Pureora population, the value of the Simpson diversity index was higher in summer than winter and was higher in Pureora compared to Eglinton. Summer Eglinton samples revealed that juvenile diets appeared to be more diverse than other demographic groups. Lactating females had the lowest dietary diversity during summer in Pureora. In Hauturu, we found a significant negative relationship between mean ambient temperature and prey richness. Our data suggest that M. tuberculata incorporate a narrower diversity of terrestrial insects than previously reported. This provides novel insights into foraging behavior and ecological interactions within different habitats. Our study is the first from the Southern Hemisphere to use molecular techniques to examine spatiotemporal variation in the diet of a generalist insectivore that inhabits a contiguous range with several habitat types and climates.

Seasonal reliance on nectar by an insectivorous bat revealed by stable isotopes

Many animals have seasonally plastic diets to take advantage of seasonally abundant plant resources, such as fruit or nectar. Switches from insectivorous diets that are protein rich to fruits or nectar that are carbohydrate rich present physiological challenges, but are routinely done by insectivorous songbirds during migration. In contrast, insectivorous bat species are not known to switch diets to consume fruit or nectar. Here, we use carbon stable isotope ratios to establish the first known case of a temperate bat species consuming substantial quantities of nectar during spring. We show that pallid bats (Antrozous pallidus) switch from a diet indistinguishable from that of sympatric insectivorous bat species in winter (when no cactus nectar is present) to a diet intermediate between those of insectivorous bats and nectarivorous bats during the spring bloom of a bat-adapted cactus species. Combined with previous results that established that pallid bats are effective pollinators of the cardon cactus (Pachycereus pringlei), our results suggest that the interaction between pallid bats and cardon cacti represents the first-known plant-pollinator mutualism between a plant and a temperate bat. Diet plasticity in pallid bats raises questions about the degree of physiological adaptations of insectivorous bats for incorporation of carbohydrate-rich foods, such as nectar or fruit, into the diet.

Pallid bat (Antrozous pallidus) foraging over native and vineyard habitats in British Columbia, Canada

Optimal foraging theory predicts organisms will forage in habitats providing the most profitable prey. Human alterations to ecosystems may affect predators’ foraging activity by changing landscape features, prey types, and prey availability. Assessing the selection of foraging habitats in a heterogeneous landscape can provide data to improve land management and conservation policies. In Canada, the pallid bat ( Antrozous pallidus (LeConte, 1856); Vespertilionidae) is listed as threatened partly because of loss or modification of shrub–steppe habitat. Our purpose was to determine if vineyards provide a suitable surrogate for foraging habitat relative to native habitat. We used pitfall traps to compare prey abundance in each habitat and analyzed faeces to assess diet composition. Over 24 nights, we surveyed both habitats for foraging bats. Bats foraged over vineyards, but we recorded significantly more foraging activity over native habitat. We collected over 2000 arthropods in pitfall traps and found significantly more in native habitat compared with vineyards. Species eaten by pallid bats were present in both habitats. Scarab beetles (Coleoptera: Scarabidae) and Jerusalem crickets (Orthopthera: Stenopelmatidae) represented the principal prey. The use of vineyards by pallid bats for foraging suggests that while they are adapting to a changing landscape, reduced prey abundance in vineyards may negatively affect them over the long term.

Testing the hindlimb-strength hypothesis: non-aerial locomotion by Chiroptera is not constrained by the dimensions of the femur or tibia

In the evolution of flight bats appear to have suffered a trade-off; they have become poor crawlers relative to terrestrial mammals. Capable walking does occur in a few disparate taxa, including the vampire bats, but the vast majority of bats are able only to shuffle awkwardly along the ground, and the morphological bases of differences in crawling ability are not currently understood. One widely cited hypothesis suggests that the femora of most bats are too weak to withstand the compressive forces that occur during terrestrial locomotion, and that the vampire bats can walk because they possess more robust hindlimb skeletons. We tested a prediction of the hindlimb-strength hypothesis: that during locomotion, the forces produced by the hindlimbs of vampire bats should be larger than those produced by the legs of poorly crawling bats. Using force plates we compared the hindlimb forces produced by two species of vampire bats that walk well, Desmodus rotundus(N=8) and Diaemus youngi (N=2), to the hindlimb forces produced during over-ground shuffling by a similarly sized bat that is a poor walker (Pteronotus parnellii; N=6). Peak hindlimb forces produced by P. parnellii were larger (ANOVA; P<0.05; N=65) and more variable (93.5±36.6% body weight, mean ± s.d.) than those of D. rotundus(69.3±8.1%) or D. youngi (75.0±6.2%). Interestingly,the vertical components of peak force were equivalent among species(P>0.6), indicating similar roles for support of body weight by the hindlimbs in the three species.

We also used a simple engineering model of bending stress to evaluate the support capabilities of the hindlimb skeleton from the dimensions of 113 museum specimens in 50 species. We found that the hindlimb bones of vampires are not built to withstand larger forces than those of species that crawl poorly. Our results show that the legs of poorly crawling bats should be able to withstand the forces produced during coordinated crawling of the type used by the agile vampires, and this indicates that some mechanism other than hindlimb bone thickness, such as myology of the pectoral girdle, limits the ability of most bats to crawl.