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Aim The Mexican long‐tongued bat (Choeronycteris mexicana), Mexican long‐nosed bat (Leptonycteris nivalis) and lesser long‐nosed bat (Leptonycteris yerbabuenae) (Phyllostomidae: Glossophaginae) undertake long‐distance migrations from south‐central Mexico to the south‐western United States. It is proposed that these bats migrate along a nectar corridor of columnar cacti and Agave species, but this has not been tested with independent data and the spatiotemporal nature of this relationship is poorly understood. Our goal was to test this nectar corridor hypothesis and determine the relative importance of food plant and abiotic variables to the distribution and seasonal movements of these migratory nectarivores. Location Mexico and the south‐western United States. Methods We generated species distribution models (SDMs) of documented food plants for these bats. We then created SDMs for each bat following a model selection approach, using food plant and abiotic predictor variables. We modelled migration pathways for C. mexicana and L. yerbabuenae using circuit theory and seasonal SDMs based on seasonally available food plants. Main conclusions Food plants were more important than climatic and topographic variables in shaping the distribution of these bats. The most important predictors of distribution were Agave, columnar cacti and species richness of food plants. Species richness of food plants was the most consistently important variable, but the components of this diversity varied by bat species: Choeronycteris mexicana was influenced by Agave and cacti; Leptonycteris nivalis was influenced solely by Agave; Leptonycteris yerbabuenae was influenced more generally by cacti, Agave and C3 plants. Migration models for C. mexicana and L. yerbabuenae provided independent support for the nectar corridor hypothesis and indicate shifts in relative importance of specific food plants throughout the year. These results suggest that conservation of these bats should focus more broadly on management for species richness of food plants, especially in tropical dry forests.

We report the results of an 11-year (2008–2018) community science project (also known as citizen science) designed to document the use of hummingbird feeders by two species of nectar-feeding bats, the lesser long-nosed bat (Leptonycteris yerbabuenae) and the Mexican long-tongued bat (Choeronycteris mexicana), in the Tucson area of southern Arizona. From 50 to > 100 households participated in this project each year. We supplemented their reports with occasional mist-netting of bats at 21 observer sites to determine age and sex composition of bats at feeders. Our results indicate that L. yerbabuenae was more widespread and common at feeders than C. mexicana, which occurred mainly at sites close to mountains. In the Tucson area, the geographic extent of feeder visitations by bats, mostly L. yerbabuenae, expanded since 2007 and by 2018, covered most of the city and its suburbs. Most bats of both species visited feeders between late August and late October with little year-to-year variation in timing; some individuals of both species continued to visit feeders during winter. The number of bats observed at many sites during September (the month of peak visitations) was relatively stable for at least 10 years; modal numbers of nightly visitors per site in most years was 6 – 10 bats. Capture data indicated that L. yerbabuenae that visited feeders in the Tucson area were not a random sample of the species' age and sex composition in southeastern Arizona, where their food plants are located in late summer and fall. In Tucson, most bats visiting feeders were subadult females (juveniles and yearlings). We suggest that hummingbird feeders have substantially increased food availability for nectar bats in southern Arizona prior to their migration south into Mexico. However, reasons for the increased use of feeders by L. yerbabuenae, particularly subadult females, beginning in 2007 are not yet clear.

Pollination is an ecosystem process that is crucial to maintain biodiversity and ecosystem function. Bats are important pollinators in the tropics and are an integral part of complex plant–pollinator interaction networks. However, network analysis–based approaches are still scarce at the plant species and bat community levels. We used metabarcoding to identify plant taxa present in pollen from fur and faecal samples collected across 1 year from three nectar‐feeding bat roosts in central Mexico. We calculated the frequency of occurrence of plant taxa and assembled a zoocentric network of bat–plant interactions. We constructed a year‐long network, encompassing the entire period of sampling, two seasonal networks comprising the wet and dry seasons, and six individual networks from sampling at two‐month intervals across the year. Four species of nectar‐feeding bats interacted with 36 plant species from 16 families. We found highly generalised interaction patterns across networks corresponding with opportunistic feeding behaviour by bats, with little seasonal variation in network structure. There was high resource overlap between bat species, and bats visited a diverse range of plant species even during periods with a high abundance of particular resources in the landscape. The diverse diet of nectar‐feeding bats emphasises the importance of floristically rich natural habitats in the landscape to provide reliable foraging resources year‐round in a seasonally variable system. While a generalised network structure is thought to increase robustness, further research is necessary to understand how fluctuations in pollinator abundance and diversity in the face of land use and climate change may impact bat–flower networks and the consequences to plant communities. Bats are important pollinators in the tropics and are an integral part of complex plant–pollinator interaction networks. We used metabarcoding to identify plant taxa present in pollen from fur and faecal samples collected across 1 year from three nectar‐feeding bat roosts in central Mexico. We found highly generalised interaction patterns across networks corresponding with opportunistic feeding behaviour by bats, with little seasonal variation in network structure.

Flight is one of the energetically most costly activities in the animal kingdom, suggesting that natural selection should work to optimize flight performance. The similar size and flight speed of birds and bats may therefore suggest convergent aerodynamic performance; alternatively, flight performance could be restricted by phylogenetic constraints. We test which of these scenarios fit to two measures of aerodynamic flight efficiency in two passerine bird species and two New World leaf-nosed bat species. Using time-resolved particle image velocimetry measurements of the wake of the animals flying in a wind tunnel, we derived the span efficiency, a metric for the efficiency of generating lift, and the lift-to-drag ratio, a metric for mechanical energetic flight efficiency. We show that the birds significantly outperform the bats in both metrics, which we ascribe to variation in aerodynamic function of body and wing upstroke: Bird bodies generated relatively more lift than bat bodies, resulting in a more uniform spanwise lift distribution and higher span efficiency. A likely explanation would be that the bat ears and nose leaf, associated with echolocation, disturb the flow over the body. During the upstroke, the birds retract their wings to make them aerodynamically inactive, while the membranous bat wings generate thrust and negative lift. Despite the differences in performance, the wake morphology of both birds and bats resemble the optimal wake for their respective lift-to-drag ratio regimes. This suggests that evolution has optimized performance relative to the respective conditions of birds and bats, but that maximum performance is possibly limited by phylogenetic constraints. Although ecological differences between birds and bats are subjected to many conspiring variables, the different aerodynamic flight efficiency for the bird and bat species studied here may help explain why birds typically fly faster, migrate more frequently and migrate longer distances than bats.

The pallid bat ( Antrozous pallidus ) is a species of western North America, inhabiting ecoregions ranging from desert to oak and pine forest. They are primarily insectivorous predators on large arthropods that occasionally take small vertebrate prey, and are at least seasonally omnivorous in certain parts of their geographic range where they take nectar from cactus flowers and eat cactus fruit pulp and seeds. Until recently, mesquite bugs were primarily tropical-subtropical inhabitants of Mexico and Central America but have since occupied the southwestern United States where mesquite trees occur. Using a noninvasive method, we investigated the bats’ diet at the Cienega Creek Natural Preserve, Arizona, by collecting food parts discarded beneath three night roosts in soil-piping cavities in a mesquite bosque. We also made phenological and behavioral observations of mesquite bugs, Thasus neocalifornicus , and their interactions with the mesquite trees. We determined that the bats discarded inedible parts of 36 species in 8 orders of mainly large-bodied and nocturnal insects below the night-roosts. In addition, one partial bat wing represents probable predation upon a phyllostomid bat, Choeronycteris mexicana . About 17 of the insect taxa are newly reported as prey for pallid bats, as is the bat C. mexicana . The majority of culled insect parts (88%) were from adult mesquite bugs. Mesquite bug nymphs did not appear in the culled insect parts. After breeding in late summer, when nighttime low temperatures dropped below 21 °C, the adult bugs became immobile on the periphery of trees where they probably make easy prey for opportunistic foliage-gleaning pallid bats. Proximity of night-roosts to mesquite bug habitat probably also enhances the bats’ exploitation of these insects in this location.

Stenocereus stellatus is an endemic, self-incompatible, columnar cactus found in central Mexico where many of its wild populations have been fragmented. As an economically important species of fruit-producing cactus, S. stellatus occurs in wild, managed in situ, and cultivated populations. The objectives of this study were to determine the effective pollinators of S. stellatus, to compare pollinator visits and reproductive parameters among the three types of populations, and to determine if nectar feeding-bats are moving among populations. Effective pollinators were the nectarivorous bats Choeronycteris mexicana, Leptonycteris curasoae, and L. nivalis. Fewer total visits per flower per night and fewer visits by Choeronycteris were observed in cultivated populations, while the opposite pattern was observed for LEPTONYCTERIS: One aggressive interaction was filmed in which Choeronycteris was physically displaced by Leptonycteris, and Choeronycteris visits were significantly affected by Leptonycteris visits. Cultivated populations received more pollen grains and had more fruit set. Variation in pollinator visits between different populations and the consequent effects on reproductive success were likely a result of competition between bat species, and differences in foraging and in sensitivity of bat species to human populations. Three marked L. curasoae traveled 15 km from their roosting site to their foraging area, and one visited cultivated and managed populations, suggesting that this species may be particularly important in moving pollen among populations.

The deserts and arid regions of North, Central, and South America are unique in the world because of the frequent dependence of their often-dominant plants (Cactaceae, Agavaceae) on nectar-feeding bats (Phyllostomidae: Glossophaginae and Lonchophyllinae) for pollination. In no other deserts have such specialized nectar bat-flowering plant mutualisms evolved. Three lineages of morphologically specialized phyllostomid nectar bats (Leptonycteris, Choeronycteris, and Platalina) are involved in this mutualism: the former two genera occur in Mexico, southwestern United States, and, in the case of Leptonycteris, northern South America whereas the latter genus occurs in the central Andes of South America. In this paper we describe the importance of Leptonycteris and Choeronycteris as pollinators of columnar cacti and paniculate agaves in North American deserts, discuss the evolutionary history of these interactions, and briefly compare these interactions with those in other Neotropical arid regions. We point out that because of their wide-ranging foraging and migratory behavior Leptonycteris bats are critical for maintaining genetic connectivity among populations of their food plants. Recent phylogenetic studies indicate that nectar bats have also been an important factor behind the high diversification rates of columnar cacti and paniculate agaves in the past 10 million years. Because of the unique ecological and evolutionary importance of these bats, their conservation should be a high priority.

Nectar-feeding animals increase their food intake when nectar sugar concentration decreases. However, some species present physiological constraints that limit their energy intake when nectar is diluted. We hypothesized that gut capacities of bats affect the ability of these animals to acquire and store energy, modifying how they use food resources in the field. We measured the food intake and changes in body mass of the members of an assemblage of nectar-feeding bats (Choeronycteris mexicana,Leptonycteris yerbabuenae, andGlossophaga soricina) feeding on sucrose solutions of different concentrations (146, 292, 438, 584, 730, 876, and 1,022 mmol L−1). The three bat species presented differences in their food intake and their capacity to store energy. WhileC. mexicanawas able to maintain a constant energy intake at all concentrations tested,G. soricinaandL. yerbabuenaedecreased their sugar/energy intake at the lowest sugar concentrations.Choeronycteris mexicanaalso increased body mass independent of sugar concentration, whileG. soricinaandL. yerbabuenaedid not. On the basis of our results, we generated a model relating gut capacities and the use of food resources in the field. Our model’s predictions and field data support the idea that digestive traits affect the way these animals use the food resources present in their environment.

The pallid bat (Antrozous pallidus) is a species of arid and semiarid western North America, inhabiting ecoregions ranging from desert to oak and pine forest. Considered primarily insectivorous predators on large arthropods but taking occasional small vertebrate prey, pallid bats were recently shown to be at least seasonally omnivorous; they demonstrate unusual dietary flexibility and opportunism in certain parts of their geographic range and at different times of year. In a few areas they take nectar from cactus flowers and eat cactus fruit pulp and seeds. Until recently mesquite bugs were primarily tropical-subtropical inhabitants of Mexico and Central America but have since occupied the southwestern United States where mesquite trees occur. Pallid bats regularly use night roosts as temporary shelters in which to process and consume large arthropods caught near their foraging areas. Using a noninvasive method, we investigated the bats’ diet by collecting food parts discarded by the bats beneath three night roosts in soil-piping cavities at the Cienega Creek Natural Preserve, Arizona. We also made phenological and behavioral observations of the mesquite bugs, Thasus neocalifornicus, and their interactions with the mesquite trees. The bats discarded inedible parts of at least 36 species in 8 orders of mainly large-bodied and nocturnal insects below the night-roosts. In addition, one partial bat wing represents predation upon a phyllostomid bat, Choeronycteris mexicana. About 17 of the insect taxa are newly reported as prey for pallid bats, as is the bat C. mexicana. The large majority of culled insect parts (88.8%) were from adult mesquite bugs. As nymphs, mesquite bugs are aposematically colored and secrete noxious pheromones; nymphs did not appear in the bat-culled insect parts. Adult mesquite bugs are darkly colored and secrete different noxious pheromones than the nymphs. During daytime hours in the summer adult bugs are abundant, flying around the canopy and alighting on the edges of the trees. In late summer and early fall they breed and lay eggs that overwinter on the mesquite branches to hatch in January. Soon after breeding, the adult bugs die. When summer heat diminishes and nighttime low temperatures drop below 21°C, the adult bugs become immobile on the periphery of the trees where they probably make easy prey for foliage-gleaning pallid bats. The historically subtropical-tropical mesquite bugs may have moved into the southwestern United States with the spread of cattle and mesquites. In this area of Arizona, pallid bats provide an important natural control on the local mesquite bug population. The high diversity of other insect remains and the remains of another species of bat provide additional supportive evidence of a diet for pallid bats that reflects their plasticity across a variety of habitats. This behavioral plasticity probably enhances the bats’ survival across their range in the face of climate change.

We studied a community of Agave species that coexist in the Metztitlán Canyon in Central Mexico. During 2001, 2002, and 2003, we analyzed floral traits and rosette allometry in five species belonging to the subgenus Littaea: A. celsii albicans, A. xylonacantha, A. difformis, A. striata, and Agave sp.; and observed floral visitors for each species. We report the first evidence of bat visitation in the subgenus Littaea and find that bats (Leptonycteris curasoae, Choeronycteris mexicana, and Glossophaga sp.) are the primary pollinators in four species. Honeybees, hummingbirds, bumblebees and hawkmoths were also common visitors. We propose that the presence of diurnal pollinators may increase the reproductive success of the plant when offering pollinator services additional to the coadapted pollinator. We also found evidence of selection pressures toward semelparity because pollinators are selecting for taller inflorescences in three of the five species. There is phenological complementarity in this community because the flowering periods of the five species span the entire year, although there are some periods when pairs of species overlap. Additionally, we found evidence for character displacement in rosette sizes and separation of spatial and temporal resource use in pollinator composition among species.