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We have compared the echolocation and feeding behaviours of Myotis lucifugus, M. californicus, M. volans, and M. auriculus based on observations and recordings of bats in the field. Myotis lucifugus and M. californicus appeared to detect prey at close range (≤ 1 m) and regularly made several attempts to capture insects over short distances; both used similar frequency-modulated echolocation calls. Myotis volans detected prey at greater distances (5–10 m), made only one attempt to capture insects per pass through a feeding area, and used an echolocation call with a distinct constant-frequency component. Myotis auriculus fed mainly on resting insects, mostly moths. The echolocation calls of this species were of shorter duration, lower intensity, broader frequency range with a higher frequency of maximum energy, and showed an initial upward sweep in frequency relative to the calls of the other Myotis we studied. Myotis auriculus did not increase their pulse repetition rate as they closed with stationary prey, and they appeared to fix on resting insects from about 2 m. This species rarely made more than one attempt to capture an insect per pass through a feeding area.

The use of frequency, duration, and patterns of frequency change over time to identify 39 species of North American and African bats by their search phase echolocation calls is described. The data were obtained from an oscilloscope display of the cells presented by a zero-crossing period meter when the calls had been detected by a broadband microphone. Species using high intensity calls are more easily sampled than those using calls of intermediate intensity; bats using low intensity calls are not readily sampled by this system. Identification of bats in the field by their calls requires observation of known individuals under field conditions. The echolocation calls included frequency components from 8 to 210 kHz. At all sites, species using frequency modulated (FM) calls with frequencies from 25 to 65 kHz predominated; larger faunas exhibited greater variability in types of calls. The identification of echolocating bats by their calls depends upon the size of the bat fauna, the levels of bat activity, and inherent characteristics of the calls.

We combined field measurements of metabolic rate, made with doubly labeled water, with data from our previous studies to examine reproductive energetics in 24 female little brown bats (Myotis lucifugus). Including estimates of tissue or milk production, M. lucifugus required an average of 33.7 kJ d⁻¹ of assimilated energy in pregnancy compared to 41.3 kJ d⁻¹ during lactation. Predicted insect consumption was 5.5 g d⁻¹ for a 9-gpregnant female and 6.7g d⁻¹ for a 79-g lactating female. About 2% of total energy assimilated during pregnancy was stored as new tissue, whereas lactating females exported 32% as milk. Estimated assimilated energy demand on the first day of lactation was 33.8 kJ d⁻¹ and increased to 60.3 kJ d⁻¹ at peak lactation. By subtracting laboratory measurements of roosting costs from observed metabolized energy expenditure, we calculated that foraging flight by 9-g pregnant M. lucifugus required 4.46 kJ h⁻¹; this was 13% less than allometric predictions. Foraging fight accounted for the larg...

Harem-like mating systems have been documented for several neotropical bat species, including Artibeus jamaicensis (Morrison 1979, Morrison & Morrison 1981), and Phyllostomus hastatus (McCracken & Bradbury 1981). The factors determining the form of mating systems in mammals are not always clear, but both resource-defence and female-defence have been identified as factors in the dynamics of bat harem systems (see reviews in Bradbury 1977 and Kunz et al. 1983). Here I report on some limited observations of the social behaviour of a small African leaf-nosed bat (Hipposideridae) from Zimbabwe. Despite some confusion in the literature (e.g. Bell & Fenton 1984), these bats are referable to Hipposideros caffer (Sundevall) (see Fenton 1986). Voucher specimens are on deposit at the Royal Ontario Museum, Toronto. Observations were made at a roost in a hollow baobab tree located in mopane woodland near the Sengwa Wild Life Research Institute (SWRI) in northwestern Zimbabwe, between 27 December 1982 and 7 March 1983. During this time I visited the roost on six occasions. The roost cavity was approximately two metres in diameter at the base, and four to five metres high, the inner walls converging to a conical peak, with a single, ground-level entrance approximately 80 cm in diameter. A human observer could, using a hand-held torch, illuminate the entire cavity from below, and see and count all bats in the cavity. On the first visit (27 December) 15 H. caffer were seen by torchlight inside the roost. Seven of these appeared to be adult females (chocolate brown to rufous-orange fur), each with a single young (dull grey-brown fur)

This study provides the first measurements of daily water flux in free-ranging bats during pregnancy and lactation. We used the wash-out rate of tritiated water from the body water pool to calculate daily water flux in 10 pregnant and 14 lactating little brown bats (Myotis lucifugus). Average water influx was 6.16 ± 0.47 (SE) mL/day during pregnancy and 6.91 ± 0.37 mL/day during lactation; average efflux was 6.27 ± 0.44 and 7.07 ± 0.36 mL/day during pregnancy and lactation, respectively. Using data from the literature, we partitioned daily flux into major components. Our calculations indicated that most (> 62%) water influx was preformed water in the insect diet. Drinking water represented 23–26% of daily influx. Although previous studies indicated that evaporative losses greatly exceeded urinary losses in laboratory-maintained M. lucifugus, urinary and evaporative losses were comparable in our free-ranging bats. Urinary losses represented 46% of water efflux during pregnancy and 35% during lactation. Over 80% of all water efflux occurs during the 8-h night.

Behavioural tests were used to examine the visual acuity and sensitivity of Macrotus californicus , a 12–14-g desert bat known to use vision in the location of terrestrial prey. Optomotor responses indicate single point visual acuity as fine as 3′38″ of arc. For comparison, the same tests were applied to two other species of bats. Antrozous pallidus , a desert gleaner which locates prey by the sounds they produce, exhibited acuity of 15′ of arc, and Eptesicus fuscus , an aerial foraging species that uses echolocation to find prey, 60′ of arc. Both M. californicus and A. pallidus retained their acuity at light levels as low as 2×10 −4 mL (approximately 2×10 −3 lux), comparable to ground luminance on a clear, moonless night. The eyes of M. californicus were more anteriorly directed, and had twice the binocular overlap of the other species examined. Comparison of our data with results from other studies indicate that M. californicus has vision superior to other insectivorous bats, and at least equivalent to larger-eyed frugivorous and nectarivorous bats examined in previous studies.

Energy metabolism, thermoregulation, and water flux ofMacrotus californicus, the most northerly representative of the Phyllostomidae, were studied in the laboratory using standard methods, and energy metabolism and water fluxes were studied in the field using the doubly labelled water method together with a time budget. Daily energy expenditures of free-living bats averaged 22.8 kJ during the winter study period. Approximately 60% of this was allocated to resting metabolism costs while in the primary roosts (22 h/day).Macrotus californicus is unable to use torpor. The thermoneutral zone (TNZ) in this species is narrow (33 to 40 °C) and metabolic rate increased rapidly as ambient temperature decreased below the TNZ. Basal metabolic rate was 1.25 ml O2/g·h, or 24 J/g·h. Total thermal conductance below the TNZ. was 1.8 mW/g·°C, similar to values measured for other bats. Evaporative water loss showed a hyperbolic increase with increasing ambient temperature, and was approximately 1% of total body mass/h in the TNZ. The success of these bats as year-round residents in deserts in the southwestern United States is probably not due to special physiological adaptations, but to roosting and foraging behavior. They use geothermally-heated winter roost sites (stable year-round temperatures of approximately 29 °C) which minimize energy expenditures, and they have an energetically frugal pattern of foraging that relies on visual prey location. These seem to be the two major factors which have allowedM. californicus to invade the temperate zone.

I examined the habitat use patterns of an Arizona insectivorous bat community using ultrasonic sensing equipment which allowed field identification of bat species based on their echolocation calls. Response to prey patchiness by the species encountered was tested using ultraviolet lights to attract swarms of insects. No partitioning of habitat or time was observed, there being a high degree of species overlap, and many species of bats appeared to be positively associated. All species responded to light-induced prey patches on at least some occasions. Analysis of prey populations indicated that food, though abundant, was extremely patchy in distribution, both spatially and temporally. These data indicate a bat community in which species are highly adapted to an abundant, but patchy food source.

Hipposideros ruber use CF/FM echolocation calls to detect the wing flutter of their insect prey. Fluttering prey were detected whether the insects were flying or sitting on a surface, and prey in either situation were captured with equal success (approximately 40% of capture attempts). Stationary prey were ignored. The bats did not use visual cues or the sounds of wing flutter to locate their prey. Wing flutter detection suggests that H. ruber exploit the Doppler-shifted information in echoes of their echolocation calls. These bats fed primarily upon moths, usually those of between 10 and 25 mm wingchord, although moths of less than 5 mm and greater than 40 mm wingchord were also attacked and captured. They showed no evidence of selecting moths on the basis of species or other taxonomic distinction, and occasionaly captured other insects.