Charles O. Handley

CHAPTER 16 – Organization, Diversity, and Long-Term Dynamics of a Neotropical Bat Community

The study of processes that influence the distribution, diversity, and abundance of species is one of the most challenging and complex fields in biology. Many basic questions are still controversial. As the results of an increasing number of studies clearly demonstrate, good data on temporal and spatial variability in community composition and species abundance are essential for formulating and evaluating hypotheses about the processes determining organization of communities and diversity of species. However, recent studies indicate that ecomorphologically similar species may be clearly differentiated by behavioral traits such as spatial segregation in habitat use, roost site selection, foraging strategies, and diet. Ecomorphological predictions alone would have placed these species closer together in the community than they actually are. Furthermore, relative abundance of well-sampled species showed individual year-to-year variation. Some frugivorous species with large seasonal variation in numbers may be migratory, but except for one species that declined, long-term population trends remained rather constant. Long-term monitoring of bats at many localities is urgently needed to build databases for intercommunity comparisons.

Neotropical bats in the canopy: diversity, community structure, and implications for conservation

We compare results of parallel ground and canopy netting of bats (Microchiroptera) in three adjacent forest sites near Belém, Brazil, to document possible differences in vertical distribution of species. We caught 1871 individuals representing 49 species of three families (Emballonuridae, Phyllostomidae, Vespertilionidae). Capture effort, totaling 1955.5 mistnet hours in several cycles over a two-year period, was similar for ground and canopy nets. The canopy rigs yielded more species (n = 41) than the ground nets (n = 35), but both samples were characterized by rank abundance curves with similar shape and with a dominance of frugivores (Phyllostomidae). Nearly half (n = 24) of the species were captured in numbers too small (n < 6) to allow firm classification, but differences in capture frequencies of some of the better-sampled species in high and low nets reveal vertical stratification. Species-specific differences in diet, foraging strategies, roost sites, and sampling bias contribute to this pattern. As a result of the differential use of space among bats, alterations of forest structure are likely to result in changes in structure and function of local bat communities, but our limited knowledge of natural history and ecology of many species limits definition of changes. We see a critical need for further research into the extent to which habitat complexity influences species richness and abundance of bats. This information is especially important in view of the need to develop and apply conservation-oriented programs to maintain biodiversity. A review of recent improvements in techniques for inventorying bats shows that a combination of methods, including mistnetting and acoustic monitoring, is mandatory for such studies.

A Biodiversity Assessment of Bats (Chiroptera) in a Tropical Lowland Rainforest of Central Amazonia, Including Methodological and Conservation Considerations

In our study of bat diversity in the Amazon Basin, we captured bats in undisturbed continuous forest and in forest fragments at the Biological Dynamics of Forest Fragments Project (BDFFP) near Manaus, Brazil, from January 1996 until July 1999. We recorded 72 species of bats in a sample of more than 7700 individuals caught during 29,900 mistnet hours in terra-firme forest. Species accumulation curves and mathematical estimates of species numbers based on the number of species captured with standardized methodology suggest that we sampled about 95% of the entire expected bat fauna of the area, including aerial insectivorous bats. Our results are similar to those of other mistnetting inventories of Amazonian bat assemblages in terms of species composition and number of species per bat family. Some species considered widespread in Central Amazonia and expected at our study site were not recorded. We interpret their absence as effects of sampling bias and of local ecological conditions. We know from acoustic monitoring (i.e., identification of bats by their echolocation calls) that our mistnet data are incomplete for aerial insectivorous species. We conclude that the development of comprehensive inventories of key vertebrate taxa such as bats derived from a combination of several standardized sampling procedures is essential to develop meaningful, conservation-oriented plans for land-use and management of protected areas. Resumo Em nosso estudo sobre diversidade de morcegos na Bacia Amazônica, nós capturamos morcegos em floresta contínua não perturbada e em fragmentos florestais no Projeto Dinâmica Biológica de Fragmentos Florestais (PDBFF), próximo à Manaus, Brazil, de Janeiro de 1996 até Julho de 1999. Nós registramos 72 espécies de morcegos capturando cerca de 7700 indivíduos em 29,900 horas de captura em áreas de terra-firme. As curvas de acumulação e modelos matemáticos baseados no número de espécies capturadas com metodologia estandartizada indicam que nós registramos cerca de 95% da fauna esperada para a área, incluindo as capturas de espécies de morcegos aéreos insetívoros. Nossos resultados são equivalentes a outros inventários baseados em redes de captura de morcegos na Amazônia, em termos de composição de espécies e em número de espécies para cada família de morcegos. Algumas espécies consideradas como uniformemente distribuídas na região Amazônica e que deveriam também ocorrer na nossa área de estudo não foram coletadas. Nós interpretamos a ausência de espécies esperadas como um efeito de limitações na metodologia e devido a condições ecológicas locais. Sabemos por monitoramento acústico (identificação de morcegos através dos sinais de ecolocação), que nossos dados de redes de captura estão incompletos para morcegos insetívoros aéreos. Nós concluímos que o desenvolvimento de inventários de grupos chave, como morcegos, com a combinação de vários métodos de amostragem estandardizados é essencial para o desenvolvimento de planos conservationistas significativos no uso da terra e no controle de áreas protegidas.

Geographic Distribution of Molossops neglectus Williams and Genoways (Chiroptera: Molossidae)

Molossops neglectus Williams and Genoways (1980) was described on the basis of one female from 1 km S, 2 km E Powaka, Suriname, now deposited in the Carnegie Museum of Natural History (CM 53864). It was previously known only from the type locality (Eisenberg, 1989). To date, males of this species have not been described. We recently collected two males in Perui, and subsequently discovered unreported specimens at the National Museum of Natural History in Washington (USNM) and the Natural History Museum, London (BM). These specimens reveal a much broader geographic range that extends to Brazil and Peru, and provide the first data on sexual dimorphism for this remarkable, but poorly known, species. The earliest record of M. neglectus is an adult male cataloged on 21 July 1851 as part of Lord Derbys collection (BM 51.7.21.19). Unfortunately, it is without data. The skull is fragmented and the braincase, right mandible, and anterior third of the left mandible are missing. On 11 March 1963, Philip Humphrey shot a juvenile male near Belem, Para, Brazil (USNM 335843). The bat was flying over secondary growth near primary lowland rain forest at about 0615 h. This specimen represents the first record of the species from Brazil. Belem is ca. 1,200 km southeast of the type locality in Suriname (Fig. 1). The skull of this specimen is also broken, but most of the trenchant features are visible. In August 1968, Merlin Tuttle collected two pregnant females from San Juan, Oxapampa, Pasco, Perui (USNM 364484 and 364485). Although Tuttle (1970) reported them as M. temmincki, they actually represent the first records of M. neglectus from Perui. This locality is about 2,800 km southwest of the type locality, and 3,200 from Belem, Brazil (Fig. 1). Both specimens have complete skulls. In July 1989, we collected one male in a mist net set about 20 m above the ground, and in December 1990, we collected a second male 25 m above the ground. The collecting site was a clearing in primary forest at the Centro de Investigaci6n Jenaro Herrera, Requena, Loreto, Perui. The specimens were deposited in the Museo de Historia Natural de la Universidad Nacional Mayor de San Marcos (MUSM 5517; 6573). The narrow clearing had been clear-cut in May-June 1989 as part of a study of forest regeneration after logging. The records of M. neglectus now known (Fig. 1) probably represent only the eastern and western margins of the true distribution. We suspect it will eventually be shown to occur in Venezuela and Colombia as well. Its occurrence in the heart of the Amazon basin may be less likely, as there are other bat species (e.g., Pteronotus gymnonotus, Micronycteris daviesi, Lichonycteris obscura, Vampyressa pusilla, and Promops centralis) that occur in northern South America and extend southward down both sides of the Amazon basin, but have as yet been unrecorded from the central part of the basin (Koopman, 1982; Mok et al., 1982). Molossid bats frequently are difficult to collect using standard techniques, and their apparent distribution patterns may be in part a reflection of our inability to detect their presence. Until the central part of the Amazon basin has been sampled systematically, the distribution patterns of many such species will remain enigmatic. The females of M. neglectus (holotype and specimens from San Juan, Peru) are similar in size (length of forearm, in mm, 35.70, 35.65, 35.75; condylobasal lengths, in mm, 15.40, 15.55, 15.95, respectively). The subadult male from Brazil is slightly larger than the females (length of forearm, 36.60 mm; condylobasal length, 16.65 mm). The adult males from Loreto are considerably larger than the other specimens (length of forearm, 38.20 mm in both; condylobasal lengths, 17.00 and 17.52 mm). Distinct sexual dimorphism is common in the family Molossidae. Any assessment of geographic variation in this species must await accumulation of additional specimens. The lower canines are short and the posterior keel is reduced in the females, and to a lesser extent in the juvenile male. These teeth are longer and much more robust in the adult males, but without an appreciable posterior keel. The upper incisors are long, but not prognathous. They are separated in females, and restricted

Bones of Mammals From West Virginia Caves

Extensive explorations of caves in eastern West Virginia have been coniducted by the Charleston Grotto of the National Speleological Society. During the period 1949-1951, R. H. Handley, assisted by R. H. Flack, J. M. Rutherford, I. T. Sanderson, and F. S. Workman, collected bones, mostly mammalian, which are reported in this paper. All material was deposited in the University of Michigan Museum of Paleontology. Specimens were picked up on or near the surface of clay floors of limestone caves and in gravel beds of subterranean streams; no digging, sifting, or washing was attempted. Stratigraphic evidence of the relative geologic ages of the bones was lacking. They possibly are not all the same age. Some may be Recent. At least some, possibly many, are probably late Pleistocene in age, possibly contemporaneous with the material from Cumberland Cave, Maryland, reported by Gidley and Gazin (1938) and Nicholas (1953). Notes on a few Cumberland Cave bones in the U. S. National Museum, not previously reported, are included in this paper. The species composition of the small sample from West Virginia caves is of such interest that further systematic collecting seems desirable.

The Shrew Sorex dispar in Virginia

Knowledge of the distribution of the supposedly rare shrew, Sorex dispar Batchelder, in the southern segment of its range has evolved rapidly in recent years. It has been reported from Pennsylvania (Richmond and Grimm, Ecology, 31: 279, 1950; reports of the Pennsylvania Mammal Survey, by various authors, 1949–52), Maryland (Mansueti and Flyger, Jour. Mamm., 33: 250, 1952), West Virginia (Jackson, North Amer. Fauna, 51:91, 1928; Wilson and Friedel, Proc. West Virginia Acad. Sei., 15: 86, 1942; McKeever, mimeo. report of West Virginia Mammal Survey, 1951), and North Carolina and Tennessee (Conaway and Pfitzer, Jour. Mamm., 33: 107, 1952). In view of the existing information on its distribution in nearby …