Describing the echolocation calls and behaviour of bats
M. BROCK FENTON 1, 2
Too often biologists use terms such as constant frequency (CF) and frequency modulated (FM) to describe the echolocation behaviour of bats or the bats themselves. While CF and FM describe echolocation calls or their components, they do not accurately depict the bats or their echolocation behaviour. By definition, over some period of time a CF signal has no bandwidth (0 kHz), while an FM signal has bandwidth (> 0 kHz). The echolocation calls produced by a wide range of species reveal that aerial feeding bats (those that use echolocation to detect, track and assess airborne prey, usually flying insects) produce high intensity echolocation calls that may include both CF and FM components. Depending upon the frequencies dominating the echolocation calls of these bats, they are detectable by most bat detectors at distances of 5 to > 10 m. In contrast, gleaning bats (those that take prey from surfaces), species that eat blood, and those that visit plants, produce low intensity echolocation calls detectable at distances of < 2 m; those of many species at " 1 m. Each of these general categories of echolocation call intensities appears in a variety of families of bats. While most echolocating bats produce their echolocation calls at low duty cycle (signal on ca. 10% of the time), separating pulse and echo in time, a few (Rhinolophidae, Hipposideridae, and the mormoopid Pteronotus parnellii) separate pulse and echo in frequency, producing echolocation calls at high duty cycle (signal on > 30% of the time). These bats can broadcast and receive at the same time. Although 'CF' accurately describes the components of some echolocation calls, it does not accurately portray the echolocation behaviour or the bats themselves. Variation in the calls of echolocating bats complicates the business of identifying species by these features alone.
Key words: Chiroptera, echolocation, constant frequency, frequency modulated, high duty and low duty cycle
Acta Chiropterologica, 1(2): 137-150, 1999 PL ISSN 1508-1109 copyright Museum and Institute of Zoology PAS
Use of ultrasound detectors for bat studies in Europe: experiences from field identification, surveys, and monitoring
INGEMAR AHLÉN 1 and HANS J. BAAGOE 2
Since 1978 we have used ultrasound detectors for field studies of European bat species and large scale mapping and monitoring in Denmark and Sweden. The method has revolutionized the field studies of bats with great possibilities and advantages. Most of the 31-32 European bat species can be identified with bat detectors, but in practical work a few species pairs may have to be lumped, e.g., Myotis mystacinus/brandtii. The species are not equally easy to find and identify, and some may need considerable time to be identified. No single variable of bat sound can be used to separate all species, and identification is often based on a number of characters in combination. Both acoustic and visual clues are of importance. Analyses of recorded sounds are valuable but do not stand alone; it is important to gain as much information as possible on the spot from the total situation in the field. We use ultrasound detectors equipped with heterodyne and time expansion systems in combination. This combination has many advantages for instant identification as well as subsequent analysis.
Key words: ultrasound detectors, heterodyning, time expansion, Chiroptera, field identification, surveys, monitoring, Europe
Acta Chiropterologica, 1(2): 151-164, 1999 PL ISSN 1508-1109 copyright Museum and Institute of Zoology PAS
Biology and management of the grey-headed flying-fox, Pteropus poliocephalus
CHRISTOPHER R. TIDEMANN
Pteropus poliocephalus is endemic to coastal eastern Australia (20-28°S), where infrequent, but extreme droughts and floods, commonly across large parts of the range, cause major swings in the availability of forage - primarily eucalypt blossom, supplemented with fruits and leaves. It can establish camps in most types of closed vegetation > 3 m in height and it can breed opportunistically. Nevertheless, camp occupation is persistent in most areas in most years, and most births coincide with the southern spring. Mean (ą SD) age at recovery of banded animals was 40.4 (ą18.8) months; the oldest was 96 months (30 recovered/1840 banded). Seventy-six percent of foraging records (n = 433) were within 20 km of the camp of origin. Pteropus poliocephalus has experienced a range reduction since European settlement and it is widely believed to be vulnerable to extinction. Possible causes of a decline are climate change, competition with congenerics, habitat loss and modification, and pest control. Conservation effort has been expended primarily on protective legislation, reservation, and promotion of the benefits of P. poliocephalus as well as other flying-foxes; the problems they cause (mostly off-reserve) have been poorly addressed and monitoring has been inadequate. Collaborative management by major stakeholders (= cost-bearers) would facilitate both the development of cost-effective and benign methods for excluding flocks from inappropriate areas, and monitoring of population status. Measures developed to manage P. poliocephalus could inform management of other flying-foxes for most problems are generic.
Key words: Pteropodidae, Pteropus, off-reserve conservation, adaptive management, biology
Acta Chiropterologica, 1(2): 165-178, 1999 PL ISSN 1508-1109 copyright Museum and Institute of Zoology PAS
Relative abundance and other aspects of the natural history of the rare golden- tipped bat, Kerivoula papuensis (Chiroptera: Vespertilionidae)
A live-trapping study was conducted to determine relative abundance, seasonality of activity, movements, and breeding season in the rare golden-tipped bat Kerivoula papuensis. All records of the species in Australia between its 'rediscovery' in 1981 and this study were the result of chance captures. Populations of the species were investigated at three sites, one in subtropical north-eastern New South Wales and two in tropical north-eastern Queensland. The species was only captured in harp traps. A total of 233 individuals were recorded at a capture rate of 14.8 individuals/100 harp trap-nights in the Richmond Range, New South Wales. Twenty-six individuals were captured in the two Atherton Tableland sites in north-eastern Queensland at a combined capture rate of 7.4 individuals/100 harp trap-nights. The sex ratio did not significantly differ from parity across all sites. The species displayed a distinct seasonal pattern in activity with capture rates peaking from mid-spring to mid-autumn when diurnal temperatures are high and nights are mild. The species was monoestrous in the Richmond Range and appeared to follow a similar strategy in north-eastern Queensland. A recapture rate of 38.4% was recorded for banded individuals in the Richmond Range, with maximum distances recorded between trap sites of 1,255 m in males and 875 m in females.
Key words: Vespertilionidae, Kerivoula papuensis, relative abundance, seasonality, capture rate, breeding season, movements
Acta Chiropterologica, 1(2): 179-190, 1999 PLISSN 1508-1109 copyright Museum and Institute of Zoology PAS
First records of 10 bat species in Guyana and comments on diversity of bats in Iwokrama Forest
BURTON K. LIM1, MARK D. ENGSTROM1, ROBERT M. TIMM2, ROBERT P. ANDERSON2, and L. CYNTHIA WATSON3
Ten species of bats (Centronycteris maximiliani, Diclidurus albus, D. ingens, D. isabellus, Peropteryx leucoptera, Micronycteris brosseti, M. microtis, Tonatia carrikeri, Lasiurus atratus, and Myotis riparius) collected in the Iwokrama International Rain Forest Programme site represent the first records of these taxa from Guyana. This report brings the known bat fauna of Guyana to 107 species and the fauna of Iwokrama Forest to 74 species. Measurements, reproductive data, and comments on taxonomy and distribution are provided.
Key words: Chiroptera, Neotropics, Guyana, Iwokrama Forest, inventory, species diversity
Acta Chiropterologica, 1(2): 191-200, 1999 PL ISSN 1508-1109 copyright Museum and Institute of Zoology PAS
Problems with the identification of southern African Chaerephon (Molossidae), and the possibility of a cryptic species from South Africa and Swaziland
PETER J. TAYLOR
Examination of recent collections of bats from KwaZulu-Natal (South Africa) and Swaziland, provisionally referred to Chaerephon cf. pumilus, reveals considerable variability in pelage colour (either greyish-brown or reddish-brown) and certain diagnostic characters of the skull and teeth from previous keys, in particular the degree of emargination of the anterior edge of the palate and the length of the maxillary toothrow. Based on the previously used key for southern African Molossidae, some specimens show diagnostic characters attributed to Chaerephon ansorgei and C. nigeriae, but in other characters, such as colour, forearm length, skull size, and relative mandible thickness, they clearly do not belong to either of these species. The obtained results suggest that the previously widely used key is inadequate for southern African Chaerephon, and a cryptic species, closely related to C. pumilus but with a partially or completely emarginated palatal condition, slightly larger forearm and skull size, better developed postaural crest, and high frequency of reddish-brown-coloured individuals, may occur in South Africa and Swaziland. A more extensive review is required to determine the relationships of this cryptic form to other African forms of the highly variable C. pumilus species-complex. A revised key to southern African Chaerephon species is presented.
Key words: Molossidae, Chaerephon, South Africa, KwaZulu-Natal, Swaziland, morphology, taxonomy
Acta Chiropterologica, 1(2): 201-208, 1999 PL ISSN 1508-1109 copyright Museum and Institute of Zoology PAS
Sugar composition of fruit and nectar and preferences of bats: causes and consequences
L. GERARDO HERRERA M.
Fruits and nectars vary in their sugar composition according to the kind of animals that ingest them. It has been hypothesized that the preferences and physiological characteristics of animals have influenced the evolution of sugar composition of plant products associated with certain groups of seed dispersers and pollinators. I review studies conducted on bats to test the generality of this hypothesis, in particular in the neotropics. The hypothesis is not supported for plants consumed by New World bats. Some alternatives to explain evolution of sugar composition in bat flowers and fruits in the neotropics are discussed.
Key words: Chiroptera, frugivory, nectarivory, sugars
Acta Chiropterologica, 1(2): 209-214, 1999 PL ISSN 1508-1109 copyright Museum and Institute of Zoology PAS
Chemical composition of leaves consumed by the lesser dog-faced fruit bat, Cynopterus brachyotis, in peninsular Malaysia
LEELA RAJAMANI1, ABDULLAH AMINAH1, AKBAR ZUBAID1, 3, KIM HOOI TAN1, and THOMAS H. KUNZ2
This study was designed to determine the chemical composition of leaves consumed by the lesser dog-faced fruit bat, Cynopterus brachyotis. Our results indicate that the mean protein content in leaves was 11.59%, whereas the mean calcium content was 7.21 mg/g dry mass. Mean tannins and phenols values were 4.13 and 8.01%, respectively. Levels of tannins and phenols were not correlated with concentrations of protein or calcium. Our results suggest that the chemical composition of leaves consumed by C. brachyotis is sufficient to meet daily protein and calcium requirements, especially during late pregnancy and lactation when energy and nutrient demands are expected to be the highest.
Key words: Pteropodidae, Cynopterus, nutrition, folivory, protein, calcium
Acta Chiropterologica, 1(2): 215-221, 1999 PL ISSN 1508-1109 copyright Museum and Institute of Zoology PAS
Growth, development, and histology of the calcar in the little brown bat, Myotis lucifugus (Vespertilionidae)
RICK A. ADAMS1 and KATHERINE M. THIBAULT2
Relative growth and development of the calcar of the little brown bat, Myotis lucifugus, are described. In addition, histological analyses are performed to determine the microstructure of the calcar. Results indicate that the calcar of this species is composed of hyaline cartilage that first appears prenatally and is the last cartilage condensation of the skeleton to form. The calcar is of adult proportions at about the time of first volancy. During juvenile development, the calcar becomes infused with calcium salts that are distributed throughout its core, from its proximal articulation with the calcaneal tuberosity to approximately one half its terminal length. The composite structure of the calcar of both hyaline cartilage and calcified cartilage provides strong yet pliable support for the uropatagium.
Key words: Vespertilionidae, Myotis lucifugus, calcar, development, histology
Acta Chiropterologica, 1(2): 223-230, 1999 PL ISSN 1508-1109 copyright Museum and Institute of Zoology PAS
Ovarian steroidogenesis in the vespertilionid bat, Scotophilus heathi: role of melatonin
ABHILASHA and AMITABH KRISHNA1
The aim of present study was to establish the role of melatonin in ovarian steroidogenesis in vitro during the reproductive cycle of Scotophilus heathi. Melatonin suppressed the synthesis of androstenedione during quiescence and recrudescence and had no effect during the period of delayed ovulation. It, however, significantly enhanced LH-induced androstenedione synthesis during the preovulatory period. It suppressed the LH-induced testosterone synthesis during winter dormancy and the preovulatory period but not during the quiescence and recrudescence phases. It enhanced LH-induced estradiol productions by the ovary during the quiescence and recrudescence phases. Melatonin also enhanced LH-induced progesterone production during recrudescence but suppressed this during the preovulatory period. The results of the present study suggest that melatonin may be involved in maintaining high circulating androstenedione concentration in S. heathi by suppressing testosterone production during the period of delayed ovulation.
Key words: Chiroptera, Scotophilus, melatonin, androstenedione, delayed ovulation, testosterone