Blossom Bat Syconycteris Australis Research Articles

Diet of an Eastern Grass Owl Tyto longimembris in northern New South Wales

A single Eastern Grass Owl Tyto longimembris was observed in Bundjalung National Park, New South Wales, in September 2019. Pellets (n = 17) collected from its roost contained the remains of House Mouse Mus musculus, Grassland Melomys Melomys burtoni, Black Rat Rattus rattus, Swamp Rat R. lutreolus, Fawn-footed Melomys Melomys cervinipes, Common Planigale Planigale maculata, Eastern Blossom Bat Syconycteris australis and honeyeater Phylidonyris sp. The most interesting findings were the Eastern Blossom Bat (the first published record of a bat in the diet of an Eastern Grass Owl in Australia) and that one of the Grassland Melomys specimens had pink bones.

Daily torpor in relation to photoperiod in a subtropical blossom-bat, Syconycteris australis (Megachiroptera)

Daily torpor in many temperate-zone mammals is affected by photoperiod. As little is known about the effects of photoperiod on torpor in subtropical species, we investigated whether, and if so how, torpor use, duration, and depth are affected by acclimation to three photoperiods (short, intermediate, long) in the blossom-bat Syconycteris australis. In contrast to many other studies, torpor occurrence, duration, and depth did not significantly respond to photoperiod acclimation in S. australis. Interestingly, the trend of a decline in torpor use under long photoperiod was the opposite of that observed previously in S. australis, which had been captured from the wild in summer and winter. Our study suggests that some species living in low latitude areas with unpredictable weather like S. australis may not use photoperiod for seasonal adjustments in physiology because it is not a reliable cue for food availability.

An Observation Of Cat Predation Upon An Eastern Blossom Bat Syconycteris Australis

WITH a body weight of 15 - 19 g and a mean headbody length of just over 60 mm (Churchill 1998), the eastern blossom bat Syconycteris australis is one of the smallest members of the sub-order Megachiroptera. Within Australia S. australis is restricted in distribution to the east coast from Cape York in Queensland to near Forster on the mid-north coast of New South Wales (NSW) (Law 1994a). Habitat requirements include both rainforest and/or wet sclerophyll forest for roosting purposes and proximal areas of heathland for foraging (Law 1993). The species survives on a diet of nectar and pollen and is heavily dependent upon Banksia integrifolia inflorescences during the winter months (Law 1994b, 1996; Coburn 1995). Blossom bats are generally regarded as solitary and exhibit strong fidelity to their feeding areas (Law 1993), although movements of up to 30 km have been reported (Law 1996).

Field metabolic rates and water uptake in the blossom-bat Syconycteris australis (Megachiroptera).

Blossom-bats, Syconycteris australis (18 g) are known to be highly active throughout the night. Since this species frequently enters torpor, we postulated that their use of heterothermy may be related to a high energy expenditure in the field. To test this hypothesis we measured field metabolic rates (FMR) of S. australis at a subtropical site using the doubly labelled water (DLW) method. We also measured DLW turnover in captive animals held at constant ambient temperature (Ta) with ad libitum food to estimate whether Ta and food availability affect energy expenditure under natural conditions. The FMR of S. australis was 8.55 ml CO2 g-1 h-1 or 76.87 kJ day-1 which is 7.04 times the basal metabolic rate (BMR) and one of the highest values reported for endotherms to date. Mass-specific energy expenditure by bats in the laboratory was about two-thirds of that of bats in the field, but some of this difference was explained by the greater body mass in captive bats. This suggests that foraging times in the field and laboratory were similar, and daily energy expenditure was not strongly affected by Ta or ad libitum food. Water uptake in the field was significantly higher than in the laboratory, most likely because nectar contained more water than the laboratory diet. Our study shows that S. australis has a FMR that is about double that predicted for its size although its BMR is lower than predicted. This supports the view that caution must be used in making assumptions from measurements of BMR in the laboratory about energy and other biological requirements in free-ranging animals.

Daily torpor and energetics in a tropical mammal, the northern blossom-bat Macroglossus minimus (Megachiroptera).

Little is known about torpor in the tropics or torpor in megachiropteran species. We investigated thermoregulation, energetics and patterns of torpor in the northern blossom-bat Macroglossus minimus (16 g) to test whether physiological variables may explain why its range is limited to tropical regions. Normothermic bats showed a large variation in body temperature (Tb) (33 to 37 degrees C) over a wide range of ambient temperatures (Tas) and a relatively low basal metabolic rate (1.29 ml O2 g-1 h-1). Bats entered torpor frequently in the laboratory at Tas between 14 and 25 degrees C. Entry into torpor always occurred when lights were switched on in the morning, independent of Ta. MRs during torpor were reduced to about 20-40% of normothermic bats and Tbs were regulated at a minimum of 23.1 +/- 1.4 degrees C. The duration of torpor bouts increased with decreasing Ta in non-thermoregulating bats, but generally terminated after 8 h in thermoregulating torpid bats. Both the mean minimum Tb and MR of torpid M. minimus were higher than that predicted for a 16-g daily heterotherm and the Tb was also about 5 degrees C higher than that of the common blossom-bat Syconycteris australis, which has a more subtropical distribution. These observations suggest that variables associated with torpor are affected by Ta and that the restriction to tropical areas in M. minimus to some extent may be due to their ability to enter only very shallow daily torpor.

Residency and Site Fidelity of Marked Populations of the Common Blossom Bat Syconycteris australis in Relation to the Availability of Banksia Inflorescences in New South Wales, Australia

Residency and site fidelity of marked populations of the nectar-feeding common blossom bat Syconycteris australis were monitored for three years in three areas of high food availability (density of Banksia integrifolia inflorescences) and three of low food availability on the north coast of New South Wales, Australia. Resident bats were present in all sites; however, populations in areas with low food abundance were more likely to be resident (63% recaptured) over a six-month flowering season than populations in areas with high food abundance (20% recaptured). Residents were more likely to be adult males, than females or juveniles. Intruder pressure fluctuated throughout the year with food abundance as the number of transients was correlated with the density of inflorescences. This had a marked effect on bats in autumn, when a lower percentage of residents than transients was reproductive in sites with high intruder pressure. Also, residents at sites with high intruder pressure were less likely to be reproductive and their body condition was lower than residents experiencing low intruder pressure. Thus intruder pressure was probably the most important factor reducing residency. Nectar and pollen was locally scarce after B. integrifolia finished flowering; however, many bats returned to the same site in the following year. Site fidelity between consecutive B. integrifolia flowering seasons (years), was greater in low-food sites (28%) than areas of high food (12%). The proximity of non B. integrifolia food sources may contribute to the degree of site fidelity, but this is yet to be tested. One site was monitored for five consecutive years and at least 4% of those marked in the first year were site faithful after five years. Strong site attachment would increase the vulnerability of this species to the effects of disturbance. These observations indicate that the abundance and dispersion of food has an important influence on behaviour and population dynamics of S. australis over long periods.