Different Species Of Bats Research Articles

Molecular Diversity of Rabies Viruses Associated with Bats in Mexico and Other Countries of the Americas

Bat rabies and its transmission to humans and other species in Mexico were investigated. Eighty-nine samples obtained from rabid livestock, cats, dogs, and humans in Mexico were studied by antigenic typing and partial sequence analysis. Samples were further compared with enzootic rabies associated with different species of bats in the Americas. Patterns of nucleotide variation allowed the definition of at least 20 monophyletic clusters associated with 9 or more different bat species. Several lineages associated with distinctive antigenic patterns were found in rabies viruses related to rabies in vampire bats in Mexico. Vampire bat rabies virus lineages associated with antigenic variant 3 are widely spread from Mexico to South America, suggesting these lineages as the most likely ancestors of vampire bat rabies and the ones that have been moved by vampire bat populations throughout the Americas. Rabies viruses related to Lasiurus cinereus, Histiotus montanus, and some other not yet identified species of the genus Lasiurus were found circulating in Mexico. Long-range dissemination patterns of rabies are not necessarily associated with migratory bat species, as in the case of rabies in Desmodus rotundus and Histiotus montanus. Human rabies was associated with vampire bat transmission in most cases, and in one case, rabies transmission from free-tailed bats was inferred. The occurrence of rabies spillover from bats to domestic animals was also demonstrated. Genetic typing of rabies viruses allowed us to distinguish trends of disease dissemination and to address, in a preliminary fashion, aspects of the complex evolution of rabies viruses in different host-reservoir species.

Genetic Divergence of Rabies Viruses from Bat Species of Colorado, USA

Molecular epidemiological studies have linked many cryptic human rabies cases in the United States with exposure to rabies virus (RV) variants associated with insectivorous bats. In Colorado, bats accounted for 98% of all reported animal rabies cases between 1977 and 1996. The genetic divergence of RV was investigated in bat and terrestrial animal specimens that were submitted for rabies diagnosis to the Colorado Department of Public Health and Environment (CDPHE), Colorado, USA. RV isolates from animal specimens across the United States were also included in the analysis. Phylogenetic analyses were performed on partial nucleoprotein (N) gene sequences, which revealed seven principal clades. RV associated with the colonial big brown bat, Eptesicus fuscus, an bats of the genus Myotis were found to segregate into two distinct clades (I and IV). Clade I was harbored by E. fuscus and Myotis species, but was also identified in terrestrial animals such as domestic cats and striped skunks (Mephitis mephitis). Clade IV was divided into subclades IVA, IVB, and IVC; IVA was identified in E. fuscus, and Myotis species bats, and also in a fox; subclades IVB and IVC circulated predominantly in E. fuscus. Clade II was formed by big free-tailed bat (Nyctinomops macrotis) and striped skunk (Mephitis mephitis) samples. Clade III included RVs that are maintained by generally solitary, migratory bats such as the silver-haired bat (Lasionycteris noctivagans) and bats of the genus Lasiurus. Big brown bats were found to harbor this RV variant. None of the Colorado specimens segregated with clades V and VII that harbor RVs associated with terrestrial animals. Different species of bats had the same RV variant, indicating active inter-species rabies transmission. In Colorado, animal rabies occurs principally in bats, and the identification of bat RVs in cat, gray fox Urocyon cinereoargenteus), and striped skunks demonstrated the importance of rabies spillover from bats to domestic and terrestrial wildlife species.

ECOLOGICAL, TAXONOMIC, AND PHYSIOLOGICAL CORRELATES OF CAVE USE BY MEXICAN BATS

Roost use by bats is likely affected by their water balance and thermoregulatory abilities. To test this hypothesis, we explored the relationship between 4 traits of different species of bats (body size, general food habits, taxonomic group, and thermoregulatory pattern) and microclimates at roosts (temperature and humidity). We recorded roost variables and presence of bats in 18 caves from 5 contrasting biomes in central Mexico. There was little evidence of microclimatic specificity among the 23 species studied, but maternity colonies used warmer roosts and hibernating bats used cooler roosts. Heterothermic species (Vespertilionidae) used colder caves with the widest temperature range (1.6–29.8°C), whereas homeothermic species (Emballonuridae, Mormoopidae, Phyllostomidae, and Natalidae) occupied warmer roosts (14.5–37.5°C). Within these caves, precise (narrow body temperature range) homeotherms occupied slightly cooler roosts than more labile homeotherms. Body size alone was not associated with cave use patterns. However, when homeotherms and heterotherms were examined separately, body size and temperature were negatively correlated. The smallest homeothermic insectivorous species (<10 g) consistently occupied roosts with temperatures >20°C (more often >25°C), whereas only the largest homeothermic insectivores were found as low as 16°C. Frugivorous, nectarivorous, and sanguivorous bats were found in a wide range of temperatures (14.5–37°C), but often at <20°C. Humidity in roosts was highly variable for most species and we did not detect any trend regarding this factor. Our data suggest that the thermoregulatory ability resulting from the complex interaction of body size, type of food, and taxonomic affiliation constrains species with respect to types of roosts that they can successfully exploit. Our results support the hypothesis that temperature is the most important physical factor influencing roost selection in bats.

Characterization of rabies virus isolates in Bolivia

In Latin America, rabies is still an important public health problem. Canine rabies, and wild animal rabies, especially transmitted by hematofagous and insectivorous bats, has become an emerging problem in the countries of this region. We received 363 samples with a laboratory-confirmed rabies diagnosis from Bolivia during l997–2001. From these, we could obtain 222 rabies virus isolates by intra-cerebral inoculation in mice. By antigenic characterization we could identify 147 isolates as variant 1, 2 isolates as variant 2, 3 isolates as variant 3, and 1 isolate as variant 5. Phylogenetic analysis of 84 isolates established that they segregated in 3 different branches, corresponding to 3 genetic variants, 78 isolates corresponding to antigenic variant 1 segregated in the same lineage as the antigenic variant 5, 2 isolates corresponding to antigenic variant 2 segregated in another lineage,, and 3 isolates from antigenic variant 3 segregated in a different lineage. The genetic variant that mainly circulates in Bolivia is maintained in a cycle whose main reservoir are dogs, but it is not possible to discard the presence of other cycles, in which different species of bats or other wild mammals could be participating.

Foraging by bats in cleared, thinned and unharvested boreal forest

Summary Modern silvicultural methods employ various styles of selective harvesting in addition to traditional clear‐cutting. This can create a mosaic of patches with different tree densities that may influence habitat use by foraging bats. Use of forest patches may also vary among bat species due to variation in their manoeuvrability. Apart from studies investigating use of clear‐cuts, few have tested for differences in use of forest patches by bats, or for differences among bat species. We investigated the influence of various harvesting regimes, which created forest patches of different tree densities, on habitat selection by foraging bats in the boreal mixed‐wood forest of Alberta, Canada. We also tested for variation in habitat selection among species related to differences in body size and wing morphology. Over two summers we assessed habitat use by bats using ultrasonic detectors to count the echolocation passes of foraging bats. We measured activity in three forest types and four tree densities, ranging from intact (unharvested) forests to clear‐cuts. Smaller, more manoeuvrable, species (Myotis spp.) were less affected by tree density than the larger, less manoeuvrable, Lasionycteris noctivagans. Two Myotis spp. differed in their habitat use. Myotis lucifugus, an aerial insectivore, preferred to forage along the edge of clear‐cuts, while M. septentrionalis, a species that gleans prey from surfaces, did not forage in clear‐cuts but preferred intact forest. The largest species in our study, L. noctivagans, preferred clear‐cuts and avoided intact patches. There were therefore differences in habitat selection by foraging bats among the species in our study area, and these were correlated with size and wing morphology. Synthesis and applications. Our results suggest that, in the short term, thinning has minimal effect on habitat use by bats. They also indicate that silvicultural methods have different immediate effects on different species of bats that may be obscured if the community is studied as a single entity. Management for forest‐dwelling bats must take such species‐specific effects into consideration. Harvesting that creates a mosaic of patches with different tree densities is likely to satisfy the requirements of more species than a system with less diverse harvesting styles.

A catalogue of bats recorded in Thrissur District, Kerala

An extensive survey and collection of specimens of 24 taxa of bats representing six families and 14 genera (barring Rhinopomatidae) were made in Thrissur District, Kerala during the years between 1990 and 1999; a few places in the northern and other central and southern districts of Kerala also were explored. All these places are agricultural areas. In the majority of cases specimens of different species of bats were collected from their roosts during day time. Total number of specimens of different species of bats collected ranges from a minimum of two to a maximum of about 550. bats were collected from their roosts during the day except those which were netted from trees, or caught during their flight in the evening or under other special cirumstances. The specimens were collected from ridges and clefts in the wall of wells, under the roofs and between tiles of roofs of houses, hollows in tree trunks, within the whorls of leaves of plantain, the grass reeds and holes underneath these, the internodal cavities of bamboo, the lofts of houses, subterranean refuges, etc. Long forceps, butterfly nets, fishing nets and Japanese mist nets were used to catch the specimens. The body weights, forearm length, fur colour, nature of mammary glands and external genitalia of females and the nature of the scrotum and the penis in the males were recorded. Several specimens of different taxa of bats under critical reproductive stages were dissected for their different genital organs and other parts, and these were fixed in appropriate fixatives and preserved. In some cases, specimens were maintained in captivity for the purpose of observing their breeding behaviour and also for conducting experiments under restricted conditions. Rest of the specimens were set free. The specimens were identified by the British Museum, London and by the Zoological Survey of India, Calcutta. Representative specimens of each species of bats collected have been deposited in these Institutes.

Renal Coccidiosis with Cystic Tubular Dilatation in Four Bats

Renal coccidiosis was diagnosed in four bats of different species (Pipistrellus pipistrellus, Myotis mystacinus, M. nattereri, and Nyctalus noctula). Multiple white and partly indented foci up to 2 mm in diameter were visible on the renal surface. Histologically, the foci appeared as cystic dilated tubules with proliferated epithelium. Asexual and sexual coccidian stages were seen in the epithelial cells, and the extremely distended tubular lumina were filled with schizonts, free zoites, microgamonts, macrogamonts, and unsporulated oocysts. Because the majority of the renal tissue appeared uninvolved in the disease process at the gross and histologic levels and there was no evidence for uremia in other organs, renal function was probably not impaired. Precise classification of the coccidia was impossible because no sporulated oocysts were available. The parasite morphology and the hitherto unreported cystic dilatation of infected tubules containing all developmental stages differ from renal coccidioses reported previously and therefore suggest an undescribed coccidian species.

A morphometric study of the lungs of different sized bats: correlations between structure and function of the chiropteran lung

1. The lungs of four species of bats, Phyllostomus hastatus (PH, mean body mass, 98 g), Pteropus lylei (PL, 456 g), Pteropus alecto (PA, 667 g), and Pteropus poliocephalus (PP, 928 g) were analysed by morphometric methods. These data increase fivefold the range of body masses for which bat lung data are available, and allow more representative allometric equations to be formulated for bats. 2. Lung volume ranged from 4.9 cm3 for PH to 39 cm3 for PP. The volume density of the lung parenchyma (i.e. the volume proportion of the parenchyma in the lung) ranged from 94% in PP to 89% in PH. Of the components of the parenchyma, the alveoli composed 89% and the blood capillaries about 5%. 3. The surface area of the alveoli exceeded that of the blood-gas (tissue) barrier and that of the capillary endothelium whereas the surface area of the red blood cells as well as that of the capillary endothelium was greater than that of the tissue barrier. PH had the thinnest tissue barrier (0.1204 microns) and PP had the thickest (0.3033 microns). 4. The body mass specific volume of the lung, that of the volume of pulmonary capillary blood, the surface area of the blood-gas (tissue) barrier, the diffusing capacity of the tissue barrier, and the total morphometric pulmonary diffusing capacity in PH all substantially exceeded the corresponding values of the pteropid species (i.e. PL, PA and PP). This conforms with the smaller body mass and hence higher unit mass oxygen consumption of PH, a feature reflected in the functionally superior gas exchange performance of its lungs. 5. Morphometrically, the lungs of different species of bats exhibit remarkable differences which cannot always be correlated with body mass, mode of flight and phylogeny. Conclusive explanations of these pulmonary structural disparities in different species of bats must await additional physiological and flight biomechanical studies. 6. While the slope, the scaling factor (b), of the allometric equation fitted to bat lung volume data (b = 0.82) exceeds the value for flight VO2max (b = 0.70), those for the surface area of the blood-gas (tissue) barrier (b = 0.74), the pulmonary capillary blood volume (b = 0.74), and the total morphometric lung diffusing capacity for oxygen (b = 0.69) all correspond closely to the VO2max value. 7. Allometric comparisons of the morphometric pulmonary parameters of bats, birds and non-flying mammals reveal that superiority of the bat lung over that of the non-flying mammal.(ABSTRACT TRUNCATED AT 400 WORDS)

Measurements of atmospheric attenuation at ultrasonic frequencies and the significance for echolocation by bats.

The absorption of sound propagating through the atmosphere under laboratory conditions of 25 degrees C and 50% relative humidity was measured at frequencies from 30 to 200 kHz. The attenuating effect on the passage of ultrasonic sounds through air ranged from 0.7 dB/m at 30 kHz. These measurements confirm theoretical expectations and earlier observations that atmospheric attenuation is progressively more severe at higher frequencies and that the atmosphere acts as a low-pass filter for conducting sounds in the frequency range used for echolocation by bats. Different species of bats use different portions of this range of frequencies, and bats emitting sonar signals predominantly above 100 kHz encounter especially severe attenuation of over 3 dB/m. With the greatly restricted operating distances for echolocation at such high frequencies, bats using these higher frequencies must be under compelling ecological pressures of a higher priority than long-range detection of targets.

Acoustic imaging in bat sonar: Echolocation signals and the evolution of echolocation

Echolocating bats behave as though they perceive the crosscorrelation functions between their sonar transmissions and echoes as images of targets, at least with respect to perception of target range, horizontal direction, and shape. These data imply that bats use a multi-dimensional acoustic imaging system for echolocation with broadband, usually frequencymodulated signals. The perceptual structure of the echolocation signals used by different species of bats was investigated using the crosscorrelation functions between emitted signals and returning echoes as indices of perceptual acuity.

Comments on animal sonar symposium

The precision and refinement of echolocation as practiced by bats and cetaceans is proving to be more and more surprising and significant as successive improvements are achieved in the procedures and apparatus used to analyze these biological sonar systems. The multiple and overlapping specializations of animal echolocation are one of their most striking features. Different species of bats employ specialized types of orientation sounds to locate and discriminate among small targets obscured by noise and clutter. Furthermore each bat adapts its sonar technique continuously as it shifts rapidly from one form of echolocation behavior to another. Further discoveries of equal significance will result from improvements that can readily be anticipated in instrumentation for measuring ultrasonic sounds of low intensity in air. Critical observations of orientation behavior under natural conditions will continue to be especially important, because many species do not reveal their full capabilities for complex echolocation under laboratory conditions.

Aerodynamic Characteristics of Some Neotropical Bats

An analysis was made of (I) the degree of correspondence of weight, wing surface area, and linear dimensions, and (2) the relationship between aerodynamic considerations, and flight and feeding behavor, for 25 species of Neotropical bats. Observed relationships of wing span versus wing area and wing span versus weight closely approach expected values, whereas observed and expected relationships of wing area versus weight do not closely correspond. Aspect ratios and wing loadings also are reported. Values for the above-mentioned features differ according to flight and feeding behavior of different species of bats. The importance of the uropatagium for flight and feeding is also examined.

The Innervation of the Bat Cochlea

For different species of bats, fixed in 5 % formaldehyd, an estimation of the number of neurons in the spiral ganglion was made. The cochleae were decalcified in EDTA and embedded in paraffin. The complete series of sections were stained with hematoxylin. On the sections through the ganglion, the number of ganglion cell nuclei was determined, with the help of an eye-piece micrometer. A 200 times magnification was used. The figures obtained with this method were corrected, with the help of Floderus’ formula: N = n. T/T + d—2k (N = the corrected estimate of the number of nuclei centres within the section; n = the observed count; T = section thickness; d = diameter of nuclei; k = vertical thickness of the smallest visible fragment). This formula helps to avoid double counting of split nuclei. After this correction the following results were obtained (table I). The numbers of Cavia, Felis and man are taken from Firbas, Wicke & Volavsek (in press), Schuknecht (1960), and Guild (1932). After comparing these numbers, it can be inferred, that the number of nerve cells in the spiral ganglion depends on the dimension of the cochlea, and on the range of perceived sounds. The neurons in the basal coil are responsible for the perception of high frequency sounds. It follows that in both the mole and the bat, the number of cells in this coil corresponds to the frequency range. The Talpidae are placed by Henson in the low frequency group. Our own investigation of the mole’s cochlea also indicates the special sensitivity of this animal to low sounds. A study of the distribution of the nerve cells to the different coils revealed interesting details. It was seen, that in the Rhinolophidae the percentage of cells belonging to the basal turn is a little lower than in Plecotus, but nevertheless much higher than in the guinea pig. In Rhinolophus 38 % of the total number of cells belongs to the basal coil, in Plecotus 48 % and in Cavia 22 %. These percentages depend on the size of the basal coil, on the arrangement of cells, and on the number of turns. Nevertheless the highest absolute values are found in bats for cochlea of that size. As usual the spiral ganglion does not extend to the apex of the cochlea. Therefore in Rhinolophus the ganglion has three turns instead of three and a half in Corti’s organ.