Olfactory discrimination ability of the short-nosed fruit bat Cynopterus sphinx

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

Nectar feeding behavior in the short-nosed fruit bat Cynopterus sphinx (Pteropodidae)

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' paradisiaca and 'big-bang' flowers of Bassia latifolia was quantified. Cynopterus sphinx typically foraged alone on flowers of M.'paradisiaca and as groups on B. latifolia, largely in response to the availability of these floral resources. Peak visits on flowers of M.'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

Wing morphology and flight development in the short-nosed fruit bat Cynopterus sphinx

Postnatal changes in wing morphology, flight development and aerodynamics were studied in captive free-flying short-nosed fruit bats, Cynopterus sphinx. Pups were reluctant to move until 25 days of age and started fluttering at the mean age of 40 days. The wingspan and wing area increased linearly until 45 days of age by which time the young bats exhibited clumsy flight with gentle turns. At birth, C. sphinx had less-developed handwings compared to armwings; however, the handwing developed faster than the armwing during the postnatal period. Young bats achieved sustained flight at 55 days of age. Wing loading decreased linearly until 35 days of age and thereafter increased to a maximum of 12.82 N m-2 at 125 days of age. The logistic equation fitted the postnatal changes in wingspan and wing area better than the Gompertz and von Bertalanffy equations. The predicted minimum power speed (Vmp) and maximum range speed (Vmr) decreased until the onset of flight and thereafter the Vmp and Vmr increased linearly and approached 96.2% and 96.4%, respectively, of the speed of postpartum females at the age of 125 days. The requirement of minimum flight power (Pmp) and maximum range power (Pmr) increased until 85 days of age and thereafter stabilised. The minimum theoretical radius of banked turn (rmin) decreased until 35 days of age and thereafter increased linearly and attained 86.5% of the rmin of postpartum females at the age of 125 days