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We studied relationships between mother and weaned young of captive Indian false vampire bats, Megaderma lyra. Four out of eight young (Group 1) at 60–63 days of age began to capture freshly killed frogs we pulled with a long thread on the sandy floor of flight room. However, the mothers continued to suckle until their young became 84.7 ± 3.97 (x̄ ± SE) days of age. When the remaining four young (Group 2) were 59.5 ± 1.85 days of age their mothers stopped suckling. Nevertheless, these mothers transferred either entire or partly consumed frogs (bodies with no heads, half bodies, paired hind limbs, and single hind limbs) to their young solicitors. Such food transfers occurred based on the body lengths of frogs. Mothers transferred small frogs entirely, but as the body length of frogs increased, mothers transferred smaller body parts to their young. Audible vocalizations of mothers and young were associated with food transfers. When these young bats became 74.0 ± 2.63 days of age, their mothers stopped food transfers. It appears that lactating females of M. lyra provision offspring by supplementing milk with solid food, similar to what has been observed in other megadermatid bats.
Of the 14 species of pteropodid bats that are found in India, Cynopterus sphinx receives most of the blame for causing damage to commercial fruit crops. We observed the number of visits made by C. sphinx to four species of commercial fruits in orchards (Mangifera indica, Achras sapota, Psidium guajava and Vitis vinifera), and four species of wild/non-commercial fruits (Muntingia calabura, Ficus bengalensis, F. religiosa and Bassia latifolia) in suburban areas. The total number of bat visits to M. calabura was significantly greater than to all other fruit species. The range of percentages of total nightly bat visits was from as low as 5% (V. vinifera) to 47% (F. religiosa), in comparison to the total nightly visits made to M. calabura. In addition, the number of mist-netted individuals of C. sphinx per hour near M. calabura was also significantly higher than near other fruit species. We suggest that if M. calabura is grown in and around orchards, damage caused by C. sphinx to commercial fruit crops may be decreased and therefore would serve as a non-destructive method for managing removal of commercial fruits by bats.
Nectar feeding behavior of the short-nosed bat, Cynopterus sphinx, was observed under natural conditions in South India. Nectar production of 'steady-state' flowers of Musa x paradisiaca and 'big-bang' flowers of Bassia latifolia was quantified. Cynopterus sphinx typically foraged alone on flowers of M. x paradisiaca and as groups on B. latifolia, largely in response to the availability of these floral resources. Peak visits on flowers of M. x paradisiaca by C. sphinx occurred at 2000 h and on B. latifolia at 2100 h. Peak visits coincided with the maximum nectar production and sugar concentration of these floral resources. In addition to feeding on nectar early in the evening, C. sphinx acquired additional energy by feeding on carbohydrate-rich fruit. In return for these food resources, C. sphinx provides important pollination and seed-dispersal services to the plants that they visit nightly, and thus can profoundly influence the co-evolution of plants and bats.
The greater short-nosed fruit bat Cynopterus sphinx relies on the diverse food resources available in its habitat, with individuals identifying and discriminating between food sources using their sense of smell, in relation to volatile compounds released from fruit, flowers and leaves. The work detailed in this article tested whether pups learn about novel food from interactions with their mothers during foraging and develop preferences. Mother-pup pairs or pups alone were trained during postnatal days (PND) 46–50 using Mangifera indica as a novel fruit. They were then tested during PND 61–65 for food preferences in relation to a known fruit (Achras sapota) and the novel fruit (M. indica). When the trained pups and untrained pups were tested for food preferences independently, those trained with the mother were found to exhibit significantly more marked preferences for the novel fruit as compared with either the pups trained without their mothers or the untrained pups. They made a greater number of feeding attempts and bouts in respect of the novel fruit. However, pups trained without their mothers and untrained pups also both showed a response to the novel fruit during the later period of testing. The results suggest that mother-pup interactions during the early foraging period may provide an opportunity for C. sphinx pups to learn about novel food sources thanks to their mother. Later they may learn independently on the basis of experience from mother's milk and/or social interaction with conspecifics.
We carried out a set of experiments on a megachiropteran bat Cynopterus sphinx to examine its olfactory discrimination ability to a variety of food odor substances. We used seven undiluted odorants such as isoamyl acetate, ethyl acetate, hexanol, benzaldehyde, limonene, pinene, and dimethyl disulfide for odor discrimination experiments. These volatile substances are present at various quantities in the natural food (fruits and nectar) of C. sphinx. Equal amount (200 μl) of seven odor substances kept individually but simultaneously in seven of eight specimen tubes which were equipped in a radially and horizontally arranged experimental set-up. In addition to the odorants, about 5 mm pieces of any one of the fruits such as guava, papaya and sapota were offered in cups as reward to the bats. The behavior of bats was observed visually and number of bat-visits to the odorants, and to the scentless control was continuously recorded in an event recorder. The mean number of approaches made by the bats differed across the odorants and scentless control (χ2 = 34.94, d.f. = 7, P < 0.001). Bats made relatively more number of visits to the odorants compared to the control, except hexanol and dimethyl disulfide. Among the odor substances, bat-visits and preference factor showed a gradational pattern with relatively maximum to ethyl acetate and minimum to dimethyl disulfide. The pattern of bat-visits was bimodal to benzaldehyde and dimethyl disulfide, whereas it was unimodal to all the remaining five odorants. Our study suggests that C. sphinx is able to discriminate different odor substances in a complex olfactory environment.
The sympatrically occurring Indian short-nosed fruit bat Cynopterus sphinx and Indian flying fox Pteropus giganteus visit Madhuca latifolia (Sapotaceae), which offers fleshy corollas (≈ 300 mg) to pollinating bats. The flowers are white, tiny and in dense fascicles. The foraging activities of the two bat species were segregated in space and time. Cynopterus sphinx fed on resources at lower heights in the trees than P. giganteus and its peak foraging activity occurred at 19:30 h, before that of P. giganteus. Foraging activities involved short searching flights followed by landing and removal of the corolla by mouth. Cynopterus sphinx detached single corollas from fascicles and carried them to nearby feeding roosts, where it sucked the juice and spat out the fibrous remains. Pteropus giganteus landed on top of the trees and fed on the corollas in situ; its peak activity occurred at 20:30 h. This species glided and crawled between the branches and held the branches with claws and forearms when removing fleshy corollas with its mouth. Both C. sphinx and P. giganteus consumed fleshy corollas with attached stamens and left the gynoecium intact. Bagging experiments showed that fruit-set in bat-visited flowers was significantly higher (P < 0.001) than in self-pollinated flowers.
We studied the patterns of postnatal growth and changes in length of forearm, body mass and total epiphyseal gap in the captive free-flying short-nosed fruit bat Cynopterus sphinx. At birth young were altricial. By day five, their eyes had opened, and the pinnae become unfolded between sixth and ninth day of age. At the age of three days, the mean forearm length and body mass were equivalent to 42.2% and 18.2%, respectively of the values of postpartum females. The length of forearm increased linearly until 36 days and attained 94.1% of mean forearm length of postpartum females at the age of 219 days. Body mass of pups increased linearly until 60 days and attained 72.7% of mean mass of postpartum females at the age of 219 days. The length of total epiphyseal gap of fourth metacarpal-phalangeal joint increased until 15 days of age and subsequently decreased linearly, and closed at about 60 days of age. The age predicting equation based on the length of forearm is valid when its dimensions are between 29.4 mm and 52.4 mm (3–36 days of age). Similar equation but based on the length of total epiphyseal gap is valid when its dimensions range from 47.0 µm to 6.0 µm (15–60 days of age). Growth patterns of forearm length and body mass were best described by the logistic and Gompertz nonlinear growth models, respectively. There was no significant difference in the growth patterns of body mass and length of total epiphyseal gap with reference to lengths of forearm of captive and wild-grown pups.
The low- and high-frequency components of a rustling sound, created when prey (freshly killed frog) was jerkily pulled on dry and wet sandy floors and asbestos, were recorded and played back to individual Indian false vampire bats (Megaderma lyra). Megaderma lyra responded with flight toward the speakers and captured dead frogs, that were kept as reward. The spectral peaks were at 8.6, 7.1 and 6.8 kHz for the low-frequency components of the sounds created at the dry, asbestos and wet floors, respectively. The spectral peaks for the high-frequency sounds created on the respective floors were at 36.8, 27.2 and 23.3 kHz. The sound from the dry floor was more intense than that of from the other two substrata. Prey movements that generated sonic or ultrasonic sounds were both sufficient and necessary for the bats to detect and capture prey. The number of successful prey captures was significantly greater for the dry floor sound, especially to its high-frequency components. Bat-responses were low to the wet floor and moderate to the asbestos floor sounds. The bats did not respond to the sound of unrecorded parts of the tape. Even though the bats flew toward the speakers when the prey generated sounds were played back and captured the dead frogs we cannot rule out the possibility of M. lyra using echolocation to localize prey. However, the study indicates that prey that move on dry sandy floor are more vulnerable to predation by M. lyra.
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