Leptonycteris Curasoae Research Articles

Potential distribution of the Curaçaoan Long-nosed Bat, Leptonycteris curasoae: implications for monitoring and conservation

Potential distribution of the Curaçaoan Long-nosed Bat, Leptonycteris curasoae: implications for monitoring and conservation

Olfactory cues of mate quality in mammals: inflammatory response is higher in males of long-nosed bats with odorous dorsal patch

Bats use olfactory signals to provide information of species and individual identity and quality. Males of two species of long-nosed bats, Leptonycteris curasoae and L. yerbabuenae, display an odoriferous dorsal patch during the mating season that is involved in mate choice. The dorsal patch is documented to serve as an indicator of male quality; for instance, males with dorsal patch present larger testes and lower ectoparasite loads. We evaluated the role of the dorsal patch in males of L. curasoae and L. yerbabuenae as an indicator of inflammatory response 6 and 12 h after being injected with phytohemagglutinin (PHA). We found that the inflammatory response of males of both species was not different between reproductively active bats with or without dorsal patch 6 h after PHA injection, but the response was higher in bats with dorsal patch 12 h after the injection. Our study adds to the evidence that the dorsal patch exhibited by males of long-nosed bats indicates their immune quality for mating females. Further work including other branches of the immune system and the potential role of microbiota in the strength of the inflammatory response is warranted.

Bat Inventories at Caves and Mines on the Islands of Aruba, Bonaire and Curaçao, and Proposed Conservation Actions

Bats play key ecological roles on the islands of Aruba, Bonaire and Curaçao (ABC islands), Caribbean Netherlands; however, most bat species on these islands are either threatened or their conservation status is unknown. We investigated the use of roosts by cave-dwelling bats in this insular system to propose conservation measures aimed at their protection. We conducted bi-monthly species inventories of cave-dwelling bats in 13 of the best-known caves and mines used as day and maternity roosts on the ABC islands. Bats were captured with mist nets and a harp trap (only one cave) placed either inside or at the entrance of the roosts during the first hours (3 to 5 hrs) after sunset. For Aruba and Curaçao, bat monitoring comprised two years of sampling. In the case of Bonaire, depending on the cave, bat monitoring involved one, two or four years of sampling. We identified six species of cave-dwelling bats associated with these roosts, Mormoops megalophylla, Pteronotus davyi, Natalus tumidirostris, Myotis nesopolus, Glossophaga longirostris and Leptonycteris curasoae. All the examined caves and mines were occupied year-round. The two abandoned mines were inhabited exclusively by the nectar-feeding G. longirostris and L. curasoae, whereas caves containing hot chambers were occupied by up to five species of bats, including insect-feeding M. megalophylla, P. davyi, M. nesopolus and N. tumidirostris, and migratory L. curasoae. Nursery roosts occupied by insect-feeding bats were Quadirikiri on Aruba; Orizjan, Pos di watapana and Pos di Antoin on Bonaire; and Raton and Noordkant on Curaçao. Nectar-feeding bats used all the caves and mines examined as day roosts, nursery roosts or both. All the cave-dwelling bats studied had a single annual reproductive period. In the case of insectivorous bats, pregnancy and lactation occurred mainly between July and December, overlapping with the rainy season. For nectar-feeding bats, pregnancy and lactation took place between March and September, overlapping with the flowering and fruiting seasons of chiropterophilous cacti. Most of the examined bat roosts require protection due to one or more of the following conditions: (1) the presence of multiple species dependent on hot chambers, (2) their use as nursery roosts, and (3) the presence of large colonies of L. curasoae.

Roosting Behaviour and Time Budgets of the CuraÇAoan Long-Nosed Bat, Leptonycteris curasoae (Phyllostomatidae, Glossophaginae) in Captivity

Bats spend half of their lifetime roosting, but their behaviour during this state has not been analysed in most species. The analysis of roosting behaviour is crucial to understand many aspects of bat ecology and social dynamics, but it can be hard to do in natural conditions, especially in cave-dwelling bats. In two species of long-nosed bats (Leptonycteris curasoae and L. yerbabuenae), reproductively active males display a unique smearing behaviour and develop an odoriferous dorsal patch during the reproductive season, presumably involved in female mate choice. As a first step to study the smearing behaviour under controlled conditions, in this study, we analysed the roosting behaviour of a captive group of 18 adult individuals (1:1 sex ratio) of L. curasoae through analysis of day-round (24 hrs) video recordings. We succeeded in producing an ethogram and in estimating the daily time budgets of the group. We also examined the effect of sex and condition of males (with dorsal patch, without dorsal patch) on behaviour. We identified 18 behaviours and classified them into five first-order categories (general maintenance, locomotion, vigilance, social and sexual) and two behavioural states (resting and self-grooming). Behaviours related to muscle and fur maintenance were the most frequent (wing stretching and self-grooming, respectively). Social behaviours (allogrooming and pushing) were relatively infrequent. The latter result suggests loose or cryptic inter-individual liaisons, probably associated with the natural dynamics of colony composition. The main difference between males and females was the expression of hugs (male to female), suggesting that this could be a sexual behaviour (pre-copulatory or pair-bonding). The behaviour of males was independent of the presence of a dorsal patch. We discuss the need for additional research to find the correlates of dorsal patch activity in order to control these variables in future studies aimed to investigate the smearing behaviour in captivity.

Agave palmeri restoration: salvage and transplantation of population structure

Agave palmeri (Palmer’s agave) is a long-lived, monocarpic, perennial succulent which provides a critical flower nectar food source for the threatened species, Leptonycteris curasoae (lesser long-nosed bat) among other animals. Agave palmeri flower only once after approximately 25 years. To support the demography needed to have some plants flowering every year, wild populations of A. palmeri must be conserved and mining, construction, and recreational impacts must be mitigated. Collecting, storing, and transplanting wild plants was tested as a potential method for restoring and maintaining A. palmeri populations. In January 2009, 387 wild plants were collected, roughly half the plants were potted in field soil, and the remainder were placed in pots without soil (bare-root) and covered with burlap cloth. During 6-months storage, 1% of plants potted in field soil died while 31% of bare-root plants died. In July 2009, a denuded and scarified field plot was planted with the surviving 277 A. palmeri individuals. Plants received one of three water treatments: a 90-day slow-release gel irrigation supplement, 8 L (2 gal) of water, or no water or gel. Three years after transplanting, survivorship was assessed. The watering treatments had no significant effect on survivorship. The number of green leaves at the time of collection was the most important factor in predicting if the plants lived, died, or survived to flower before dying . Mortality is concentrated in the smallest and largest plants. Transplanting appears to be a viable method of returning diverse size classes of A. palmeri to disturbed sites.

Tracking the origin of the smearing behavior in long-nosed bats (Leptonycteris spp.)

A unique and novel stereotypic ‘smearing’ behavior and the formation of an odoriferous dorsal patch have been recently described in two species of long-nosed bats, Leptonycteris curasoae and L. yerbabuenae (Glossophaginae: Phyllostomidae). It has been hypothesized that this structure represents a mechanism involved in female mate choice mediated through odor, and that it has only evolved within the genus Leptonycteris. No evidence has been published indicating whether the smearing behavior and the dorsal patch occur in L. nivalis, the third extant species within the genus. We reviewed the available data on the mating behavior of L. nivalis and conducted four surveys on the only mating colony known for this species at Cueva del Diablo, Tepoztlan, Morelos, Mexico, searching for evidence of both the smearing behavior and the dorsal patch in reproductive males of this species. Our findings indicate that L. nivalis does not display the smearing behavior or the dorsal patch, suggesting that this trait and its role in mate choice by females must have evolved from a common ancestor of L. yerbabuenae and L. curasoae after it separated from L. nivalis, between 1.0 and 0.5 million years ago. We propose a possible hypothetical scenario for the evolution of the smearing behavior, based on differential levels of ectoparasitic pressure acting on bat populations established at locations with markedly different environmental temperatures.

Island–island and island–mainland movements of the Curaçaoan long-nosed bat,Leptonycteris curasoae

Of the 3 species comprising the genus Leptonycteris Miller, L. curasoae has been the least studied with respect to its long-distance flights and potential for seasonal migrations. We studied long-distance movements between islands and between islands and the mainland in the Curaçaoan long-nosed bat. We used mark–recapture with periodic sampling and marking of bats in Aruba, Curaçao, Bonaire, and 1 location (Butare) in Falcón State, on the Venezuelan coastline. Between October 2008 and April 2014, we captured a total of 7,518 individuals at 11 sites (Aruba: n = 1,827, Curaçao: 778, Bonaire: 4,128, and Butare: 785). Between 78.3% and 98.0% of the bats captured at each island and mainland were marked, and the overall percentage of recaptured animals across all sampling sites was 8.31% (n = 529). L. curasoae inhabits the 3 islands year-round. On each island, it roosts in several caves, which can be used alternatively by the same individuals. Despite being a resident species, L. curasoae can perform long-distance oversea flights between islands and between islands and the South American mainland. A total of 11 long-distance flights were recorded (2 Bonaire–Aruba, 4 Bonaire–Curaçao, 1 Curaçao–Bonaire, 1 Bonaire–Venezuela, and 3 Aruba–Venezuela). We propose that populations of this species in Aruba, Curaçao, Bonaire, and Falcón State, Venezuela, exchange individuals, and part of the insular populations migrate seasonally southward as a response to cyclical changes in local resource availability and the yearly reproductive regime. De las 3 especies que comprenden al género Leptonycteris Miller, L. curasoae ha sido la menos estudiada con respecto a sus vuelos de larga distancia y potencial para migraciones estacionales. Estudiamos los movimientos de larga distancia entre islas, y entre islas y tierra firme en esta especie, usando marcado y recaptura con muestreos periódicos y anillado de murciélagos en Aruba, Curaçao, Bonaire, y una localidad (Butare) en el estado Falcón, en la costa venezolana. Capturamos un total de 7518 individuos en 11 sitios (Aruba: n = 1827, Curaçao: 778, Bonaire: 4128, Butare: 785). Entre 78,3 % y 98,0 % de los murciélagos capturados en cada isla y tierra firme fueron marcados, y el porcentaje total de animales recapturados en todos los sitios de muestreo fue de 8,31 % (n = 529). L. curasoae habita las 3 islas durante todo el año. En cada isla, se refugia en varias cuevas, las cuales pueden ser usadas alternativamente por los mismos individuos. A pesar de ser una especie residente, L. curasoae puede realizar vuelos de larga distancia sobre el mar entre islas, y entre islas y tierra firme de América del Sur. Un total de 11 vuelos de larga distancia fueron registrados (2 Bonaire-Aruba, 4 Bonaire-Curaçao, 1 Curaçao-Bonaire, 1 Bonaire-Venezuela, y 3 Aruba-Venezuela). Proponemos que las poblaciones de esta especie en Aruba, Curaçao, Bonaire, y el estado Falcón, Venezuela, intercambian individuos y parte de las poblaciones insulares migran estacionalmente hacia el sur, como una respuesta a cambios cíclicos en la disponibilidad de recursos a nivel local y al régimen reproductivo anual.

Assessing Emergence of a Long-Lived Monocarpic Succulent in Disturbed, Arid Environments: Evaluating Abiotic Factors in Effective Agave Restoration by Seed

Agave palmeri Engelmann is a semelparous perennial succulent thought to provide a critical food source for the endangered species, Leptonycteris curasoae Miller. Concern over impacts to existing A. palmeri populations has accelerated interest into reestablishing populations after disturbance. Little is known about its early life history and potential for restoration by seed in its arid habitat. In a greenhouse we measured emergence for 5.5 months across treatments with four variables: simulated precipitation (low: 170 mm, average: 285 mm, high: 390 mm), shade (present, absent), surface mulch (straw, gravel, bare soil), and soil type (sand, sandy loam, loamy sand). The highest emergence was associated with high simulated precipitation (33%), straw mulch (42%), shade (38%), and the loamy soils (mean: 30%). High simulated precipitation on shaded, straw mulched treatments had the highest overall emergence (63%). Lowest emergence involved low simulated precipitation (11%), bare soil (9%), absence of shade (10%), and sandy soil (10%). Low levels of simulated precipitation, combined with unshaded, bare soil treatments—conditions common in heavily disturbed arid environments—had zero seedling emergence. Our results indicate that microsite conditions play a crucial role in the emergence of this species, and manipulation of these conditions may significantly increase emergence, even when water availability is low. This is critical information for land managers attempting to recover populations, as duration and frequency of rainfall are characteristically variable in regions A. palmeri inhabits. Thus, the use of surface mulches and shade may effectively facilitate restoration in large-scale disturbances when unfavorable conditions cannot be controlled.

Trypanosoma evansi kDNA minicircle found in the Venezuelan nectar-feeding bat Leptonycteris curasoae (Glossophaginae), supports the hypothesis of multiple origins of that parasite in South America

Trypanosoma evansi is a mammal generalist protozoon which causes negative effects on health and productivity in bovine and equine herds in South America, Europe, Asia and Africa. By molecular methods, we screened the presence of that parasite together with other trypanosome species in 105 bats of 10 species collected in arid zones of northern Venezuela. The first molecular approach was fluorescent fragment length barcoding (FFLB), which relies on amplification of relative small regions of rRNA genes (four loci) and fluorescence detection. By FFLB, 17 samples showed patterns of possible trypanosomatid infections. These samples were used to test presence of trypanosomes by PCR using the following DNA markers: V7–V8 SSU rRNA, gGAPDH and kDNA minicircle regions. Only in one individual of the nectar-feeding bat, Leptonycteris curasoae, we were able to amplify 1000bp of the trypanosome kDNA minicircle. That PCR product was sequenced and the parasite species was determined by NCBI-BLAST and phylogenetic analysis. Both analyses showed that the minicircle sequence corresponds to Trypanosoma evansi. The phylogenetic analysis of the sequence obtained in this study clustered with a T. evansi sequence obtained in a Venezuelan capybara, Hydrochoerus hydrochaeris, and distant of others two T. evansi sequences obtained in a Colombian capybara and horse. This result supports the hypothesis of multiple origins of T. evansi in South America.

Chemical Composition of the Substances from Dorsal Patches of Males of the CuraÇAoan Long-Nosed Bat,Leptonycteris curasoae(Phyllostomidae: Glossophaginae)

In the absence of visual cues, chemical signals are especially important for nocturnal mammals such as bats, because they facilitate individual recognition, communication, and mate selection. In a recent study, it was reported that adult males of the Curaçaoan long-nosed bat, Leptonycteris curasoae, develop an odoriferous dorsal patch during the short mating season. It was postulated that dorsal patches signal health condition to females, and that females are preferentially attracted to the odor of males with dorsal patches. The chemical characterization of the dorsal patch is key to understanding its implications in chemical communication in a sexual context. In the present study, organic compounds collected from dorsal patches of males of L. curasoae from northwestern Venezuela were extracted using solid-phase micro-extraction (SPME) techniques and tentatively identified using GC-MS (Gas Chromatography-Mass Spectrometry). Nineteen compounds were present in 75% or more of the patches examined: 3-methyl-2-buten-1-thiol, acetic acid, 2′-aminoacetophenone, diacetyl, 2-pentanone, 2,3-dimethylpyrazine, 2-nonanone, acetamide, 2-undecanone, piperidinone, 4-methylquinazoline, 2,4-dimethylquinazoline, 3-methyl-2,5-pyrrolidinedione, 2-butanone, 2-methylfuran, 3-methyl-2-butenal, δ-valerolactone, 3-methyl-2-butenoic acid, and 2-methyl-2-butenoic acid. Although some of these compounds have been reported as important in female attraction among other male mammals during their respective breeding seasons, the actual function of these chemicals in L. curasoae remains to be determined. Some of these compounds have also been identified as natural insecticides, and this may be associated with lower ectoparasite loads reported on males with dorsal patches. These results, when considered along with previous observations, suggest that the dorsal patch in males of L. curasoae promotes the attraction of females during the mating season, and/or provides protection against ectoparasites.

The Dorsal Patch of Males of the Curaçaoan Long-Nosed bat,Leptonycteris curasoae(Phyllostomidae: Glossophaginae) as a Visual Signal

The seasonal dorsal patch of males of the Curaçaoan long-nosed bat, Leptonycteris curasoae, which exhibits variability in size, shape, and chemical complexity, is a trait associated with courtship and mating in this species. This recently discovered structure develops exclusively during the mating season that occurs once a year between November and December in populations of L. curasoae from northern Venezuela. Although the dorsal patch that develops in males has unique chemical characteristics possibly involved in female attraction, we suggest that this trait also sends distinct visual cues regarding the health status of males. We evaluated the postulated association between dorsal patch shape (symmetry) and ectoparasite load (streblid batflies) in males of L. curasoae. To do so, we quantified the shape of dorsal patches on males to test the hypothesis that streblid load was related to this variable. Over 2,000 streblid batflies of two different species (Nycterophilia coxata and Trichobius sphaeronotus) were recovered from 130 individuals ( = 16 streblids/bat). Among these batflies, N. coxata was the most abundant species found on L. curasoae (2,042 individuals, 95.0% prevalence). Males with dorsal patches had significantly lower batfly loads when compared with males without dorsal patches and with females. Males with the most symmetrical dorsal patches also had the lowest batfly loads. Our results suggest that the odoriferous dorsal patches produced in males of L. curasoae also convey visual cues to female mates as signals of good health.

Smearing behaviour of male Leptonycteris curasoae (Chiroptera) and female responses to the odour of dorsal patches

Smearing behaviour of male Leptonycteris curasoae (Chiroptera) and female responses to the odour of dorsal patches

Registros nuevos de murciélagos para el Centro de Investigaciones Costeras La Mancha, Actopan, Veracruz

We report 8 new records of bats for the Centro de Investigaciones Costeras La Mancha (CICOLMA), located in the coastal zone of Actopan, Veracruz, Mexico, accounting for a total of 23 species. The new records belong to Phyllostomidae (Artibeus intermedius, Chiroderma villosum, Uroderma bilobatum, Centurio senex, Leptonycteris curasoae), Mormoopidae (Mormoops megalophylla) and Vespertilionidae (Myotis fortidens, Myotis velifera) families. The conservation efforts of the CICOLMA biological station are important, because in spite of its small area, it keeps an important bat diversity from the coastal region of Veracruz.

Primer registro de una colonia de Leptonycteris curasoae (Chiroptera: Phyllostomidae) en Baja California, México

We report the first record of a colony of the phillostomid bat Leptonycteris curasoae for Baja California, Mexico. This region represents the second locality reported for this species in the state.

Dorsal Patch and Chemical Signaling in Males of the Long-Nosed Bat,Leptonycteris curasoae(Chiroptera: Phyllostomidae)

Adult males of the long-nosed bat (Leptonycteris curasoae) produce odoriferous ‘‘sebaceous’’ secretions in the interscapular region (dorsal patch), exclusively during the mating season (November–December). These dorsal patches might play a role in mate selection by L. curasoae in northern Venezuela. We evaluated differences between body traits of males with and without dorsal patches to determine whether these structures could be used by females as indicators of male quality, examined whether the size of the dorsal patch shows a relationship with other body traits during the mating season, and investigated the physical and behavioral development of dorsal patches. Thirty-seven percent of all males sampled (n 5 99) showed conspicuous dorsal patches during the mating season in November and December. Males with conspicuous dorsal patches had larger testes, smaller body masses, lower body condition indices, and lower ectoparasite loads than males without dorsal patches. Larger testes and lower ectoparasite loads suggest that the dorsal patch could be signaling male quality and readiness for mating. A typical dorsal patch covered approximately 1.7 cm 2 of a male’s interscapular region, but size of this structure did not vary with any of the body traits examined. We describe a novel, stereotypic behavior performed by male L. curasoae, which we call ‘‘smearing behavior,’’ and suggest that this is associated with development of the dorsal patch because males appear to smear different body fluids onto this patch. We further suggest that sebaceous secretions in the interscapular region would not be the determining factor in dorsal patch development.

Patterns of island occupancy in bats: influences of area and isolation on insular incidence of volant mammals

ABSTRACTAim The influence of landscape structure on the distribution patterns of bats remains poorly understood for many species. This study investigates the relationship between area and isolation of islands and the probability of occurrence of six bat species to determine whether persistence and immigration abilities vary among bat species and foraging guilds.Location Thirty‐two islands in the Gulf of California near the Baja California peninsula in north‐west Mexico.Methods Using logistic regression and Akaike information criterion (AIC) model selection, we compared five a priori models for each of six bat species to explain patterns of island occupancy, including random patterns, minimum area effects, maximum isolation effects, additive area and isolation effects and compensatory area and isolation effects.Results Five species of insectivorous bats (Pipistrellus hesperus, Myotis californicus, Macrotus californicus, Antrozous pallidus and Mormoops megalophylla) displayed minimum area thresholds on incidence. The probability of occurrence tended to decrease at moderate distances of isolation (c. 10–15 km) for these species (excepting A. pallidus). The distributions of two non‐insectivorous species (Leptonycteris curasoae and Myotis vivesi) were not influenced by island size and isolation.Main conclusions Minimum area thresholds on incidence suggest that island occupancy by insectivorous bats may be limited by resource requirements. Islands smaller than 100 ha typically did not support occupancy or use by insectivorous bats, except at minimal isolation distances. Insectivorous bat species may also be more sensitive to moderate levels of habitat isolation in some landscape contexts than previously expected. Our results suggest that differences in foraging habits may have important implications for understanding the distribution patterns of bats.

Seasonal sebaceous patch in the nectar-feeding bats Leptonycteris curasoae and L. yerbabuenae (Phyllostomidae: Glossophaginae): phenological, histological, and preliminary chemical characterization

Many species of bats secrete a wide variety of substances, frequently associated with olfactory communication. We characterized a seasonal phenomenon of dorsal sebaceous secretion in the Curaçaoan long-nosed bat, Leptonycteris curasoae, in Venezuela, and the lesser long-nosed bat, Leptonycteris yerbabuenae, in Mexico. The phenology of the sebaceous patch was determined, a histological analysis of the affected area was conducted using specimens of L. curasoae from Venezuela, and finally, a preliminary chemical characterization of the substance secreted was performed combining histochemical techniques with gas chromatography and mass spectrometry analyses. The sebaceous patch was detected exclusively in male adult specimens. Individuals presenting it had a variable area of fur covered with a fatty and odoriferous substance at the level of the interscapular zone. Occurrence of the sebaceous patch was cyclical and coincided with the mating season in Venezuela and Mexico. The following histological changes associated with occurrence of the patch were observed: increase of epidermis thickness and decrease of dermis and hypodermis thicknesses, increase in density of sebaceous glands, increase of percentage of skin covered by sebaceous glands, increase of size of sebaceous glands previous to secretion followed, and increase of the sebum volume within sebaceous glands previous to secretion. Several compounds tentatively identified as fatty acids, cholestanes and cholesterol were present in the sebaceous secretion. Based on the evidence obtained, we hypothesize that the sebaceous patch could be involved in olfactory communication, possibly related to mating behavior in these bats.

The intake responses of three species of leaf-nosed Neotropical bats

Flower-visiting bats encounter nectars that vary in both sugar composition and concentration. Because in the new world, the nectars of bat-pollinated flowers tend to be dominated by hexoses, we predicted that at equicaloric concentrations, bats would ingest higher volumes of hexoses than sucrose-containing nectars. We investigated the intake response of three species of Neotropical bats, Leptonycteris curasoae, Glossophaga soricina and Artibeus jamaicensis, to sugar solutions of varying concentrations (292, 438, 584, 730, 876, and 1,022 mmol L(-1)) consisting of either sucrose or 1:1 mixtures of glucose and fructose solutions. Bats did not show differences in their intake response to sucrose and 1:1 glucose-fructose solutions, indicating that digestion and absorption in bat intestines are designed under the principle of symmorphosis, in which no step is more limiting than the other. Our results also suggest that, on the basis of energy intake, bats should not prefer hexoses over sucrose. We used a mathematical model that uses the rate of sucrose hydrolysis measured in vitro and the small intestinal volume of bats to predict the rate of nectar intake as a function of sugar concentration. The model was a good predictor of the intake responses of L. curasoae and G. soricina, but not of A. jamaicensis.

Effects of Sugar Composition and Concentration on Food Selection by Saussure's Long-nosed Bat (Leptonycteris curasoae) and the Long-tongued Bat (Glossophaga soricina)

In the Neotropics, bat-pollinated plants secrete relatively dilute nectars dominated by hexoses (glucose and fructose) with only small amounts of sucrose. We investigated the concentration and sugar composition preferences of Saussure's long-nosed bat (Leptonycteris curasoae) and the long-tongued bat (Glossophaga soricina) to test the hypothesis that bats prefer the predominant characteristics (sugar composition and concentration) found in their natural diets. We offered bats pairs of test diets in large outdoor enclosures that allowed free flying. We used artificial nectars that simulated compositions and concentrations found in flowers visited by these 2 species at the study site. Contrary to our predictions, bats showed no preference between sugar types when test solutions had the same concentration. However, L. curasoae preferred concentrated over dilute solutions independent of sugar type. Only 1 preference for concentrated over dilute solutions was recorded for G. soricina. Both species of bat appeared to perceive sugar types as energetically equivalent in most trials. Our study rejects the hypothesis that nectar-feeding neotropical bats act as a selective pressure on nectar composition in chiropterophilous plants. Other possible explanations for the predominance of hexose in chiropterophilous flowers need to be evaluated.

Effectiveness of bats as pollinators of Stenocereus stellatus (Cactaceae) in wild, managed in situ, and cultivated populations in La Mixteca Baja, central Mexico

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.