Suchergebnisse

The diet of the common blossom bat
(Syconycteris australis) was investigated in upland
rainforest on the Atherton Tablelands. Faeces or fur pollen samples from 62
S. australis and feeding observations on 5 captive and
10 radio-tagged bats were collected.
Syconycteris australis fed on blossoms from at least 18
plant species found in rainforests (plus unidentified species of
Loranthaceae), 2 species from non-rainforest communities and from flowers of
the cultivated banana (Musa sp.) grown on farms.
Rainforest plants included 13 species of trees, 1 shrub and 4 climbers.
Myrtaceae was the most important family contributing to the diet of
S. australis, particularly the genus
Syzygium. The chiropterophilus flower syndrome was only
partly useful as a predictor of the diet of S. australis
in these forests. Fruit was also eaten, being most common in the diet from
late summer to autumn (wet season). Twelve months of mist-netting in riparian
and non-riparian rainforest found higher capture rates in riparian rainforest
in spring and summer, but not during autumn or winter. It is suggested that
the availability of food species (both blossom and fruit) is high in riparian
rainforest during spring and summer when S. australis is
most frequently caught in this habitat. Efforts to rehabilitate rainforest
along degraded creeks should offer a significant conservation benefit to this
small pollinator.

The roosting and foraging ecology of the golden-tipped bat (Kerivoula papuensis) was studied by radio-tracking on the south coast of New South Wales. Despite a previous scarcity of records, 16 bats were harp-trapped during spring and summer, of which 11 were radio-tracked. Roost types (n = 33 roosts over 48 roost days) were the suspended nests of yellow-throated scrubwrens (Sericornis citreogularis) (50%), nests of brown gerygone (Gerygone mouki) (27%), beneath hanging moss on tree trunks (21%) and in foliage (2%). All roosts were located in rainforest and close to creek lines (mean = 6 m). Yellow-throated scrubwren nests were more common in rainforest on small, first- and second-order streams (4.6 nests km–1 – 5.2 km searched) than on larger, third-order streams (1.1 nests km–1 – 2.7 km searched). Colonies were small (<10 bats) and usually comprised a mix of sexes. Maternity roosts in summer were located in both yellow-throated scrubwren nests (n = 8) and brown gerygone nests (n = 3). Foraging bats were recorded flying a maximum of 2.1 km and were regularly recorded (43% of monitored time) on upper slopes away from rainforest. Plots (5 × 5 m) were used to compare prey densities (small web-building spiders) between rainforest and sclerophyll forest and different topographies (creeks, riparian vegetation and upper slopes). Although spider numbers were patchy, upper-slope sclerophyll forest supported the greatest number of spiders, the number being significantly greater in upper-sclerophyll forest than in sclerophyll creeks and rainforest on upper slopes. A forward step-wise multiple regression showed that spider numbers per plot were positively related to the density of understorey stems. Management implications from this research are that riparian rainforest provides the key roosting habitat for K. papuensis. Recent management prescriptions in New South Wales' forests available for logging have correctly targeted the protection of this environment. However, the extent of foraging in sclerophyll forest on upper slopes was previously unknown. Attention needs to be given to management actions that maintain a mosaic of dense patches of understorey on upper slopes, where the numbers of web-building spiders are high. Further research is required to determine the effectiveness of using buffered protection zones within logged areas for K. papuensis.

Context
Environmental benefits of timber plantations have been a major selling point for land use change from previously cleared farmland, but data concerning the response of biodiversity are scarce.


Aims
We investigated the use of young (4–11 years old) timber plantations by bats in comparison with other vegetation classes in a highly cleared and productive agricultural landscape in north-west New South Wales (NSW), Australia.


Methods
Initially, we recorded activity in paddocks before plantation establishment, and then four to six years after establishment. We compared activity within young eucalypt plantations with surrounding paddocks and remnant woodland. We also radio-tracked four different bat species to investigate how roosting and foraging was apportioned into different habitats.


Key results
The ultrasonic survey of bats found that the young plantations were typically used by 7–8 species and activity averaged 87 passes per night. Activity within plantations was similar to treeless paddocks, and approximately six times less than in small remnants. The very high activity levels and feeding buzzes in small remnants was significantly related to rich, basalt soil (which was used as a proxy for invertebrate biomass) on agricultural plains. Total activity and species richness was correlated positively with the number of remnant trees on the site, but neither plantation area nor shape influenced bat activity. Plantations were not used preferentially by radio-tracked bats at night compared with their availability in the local landscape (13–14% bat use, 17% available). No bat roosts were located within the plantations. Most bat roosts were in tree hollows, which were absent in the plantations. Decorticating bark was abundant in eucalypt plantations, but only Nyctophilus geoffroyi was observed beneath bark and only in remnant trees outside of plantations.


Conclusions
Young eucalypt plantations have limited value for bats, and this is comparable to previous studies on more environmentally focussed plantings.


Implications
The value of plantations for bats would be improved by retaining remnant trees, both in the surrounding landscape and within plantations. We also recommend varying tree densities to increase the diversity of animal species using plantations.

Context
Maternity roosts of insectivorous bats (where females raise young) are critical to the conservation of threatened species as roost quality can influence reproductive success. Additionally, threatened species may have specialised requirements or unusual behaviour, which may be overlooked without targeted investigation.

Aims
To explore which factors influence the roost selection of Mormopterus norfolkensis, by comparing day roosts, identified via radio-tracking, with environmental variables collected at tree, patch and landscape scales.

Methods
We collected a range of variables describing maternity roosts and surrounding patches, including internal measurements of hollows and microclimate. Additionally, we derived landscape-scale variables using a geographic information system. We then explored which variables best explained roost occurrence using logistic regression.

Key results
Nineteen lactating females and two male M. norfolkensis were tracked to 40 roost trees, mostly grey mangrove, Avicennia marina subsp. australasica. Lactating females were found to be faithful to two patches of mangrove forest close to where they were captured, regularly switched roosts and roosted in hollows singularly or in small groups. The attributes of mangrove patches, especially a high proportion of hollows, better predicted roosting by lactating females than roost-tree or landscape characteristics. Additionally, although the microclimate of roost hollows was not significantly different from ambient mangrove conditions, the mangrove forest was slightly more stable and had higher humidity than did other nearby habitats.

Conclusions
Contrary to predictions, maternity roosting group sizes were relatively small, indicating that bats were not deriving thermoregulatory benefits from communal living. However, we suggest that lactating females may benefit from the operation of a fission–fusion society among the colony as a whole. Additionally, the mature mangrove forest could offer unique roosting opportunities for bats because they support high densities of hollow-bearing trees, a stable microclimate and potentially low abundances of predators and competitors.

Implications
This is one of few international bat–mangrove studies and it illustrates that threatened species can behave unexpectedly and may be overlooked in conservation strategies that are based largely on anecdotal observations. We encourage further research into the value of mangrove forests to terrestrial fauna globally.

We investigated the effects of insect-attracting ultraviolet lights on activity of forest bats (Microchiroptera) with the prediction that lights would increase our indices of bat activity and improve species identification of recorded echolocation calls. Insect aggregations were created on forest tracks (n = 9) near Kioloa, New South Wales, using three vertically stratified insect light traps. Bat echolocation calls were recorded using a ground-based vertically oriented Anabat II detection system. Bat activity and foraging rates were higher at lit points than at unlit points, particularly when the lights were operated in full darkness. More species were identified at lit points and the sampling time required to identify the second to the fifth new species was 3.3–4.6 times shorter with lights. The presence of lights resulted in a greater number of bat passes more than five pulses in length, which was associated with an increased ability to identify passes to species level. Our study demonstrates that the use of lights in forest-based echolocation surveys can improve bat species inventories, particularly in communities where overlap in call characteristics among species is common.