Movement patterns of southern bell frogs (Litoria raniformis) in response to flooding

2008 ◽  
Vol 35 (1) ◽  
pp. 50 ◽  
Author(s):  
Skye Wassens ◽  
Robyn J. Watts ◽  
Amy Jansen ◽  
David Roshier

Within the semiarid regions of New South Wales, Australia, the endangered southern bell frog (Litoria raniformis) occupies a landscape that is characterised by unpredictable rainfall and periodic flooding. Limited knowledge of the movement and habitat-occupancy patterns of this species in response to flood events has hampered conservation efforts. We used radio-tracking to assess changes in movement patterns and habitat occupancy of L. raniformis (n = 40) over three different periods (November, January and April/May) that coincided with the flooding, full capacity and subsequent drying of waterbodies within an irrigation landscape. We assessed (1) the use of permanent and ephemeral habitats in response to flooding and drying and (2) distances moved, turning angles and dispersion of frogs during wetland flooding, full capacity and drying. Individuals remained in permanent waterbodies in November but had abandoned these areas in favour of flooded ephemeral waterbodies by January. As the ephemeral waterbodies dried, radio-tracked individuals moved back into permanent waterbodies. The movement patterns of radio-tracked individuals were significantly different in the three radio-tracking periods, but did not differ significantly between sexes. Individuals moved significantly greater distances over 24 h, in straighter lines and movements were more dispersed while they occupied ephemeral waterbodies during January than when they occupied permanent waterbodies during November and April/May. Local weather conditions did not influence movement patterns when all three tracking periods were modelled together using a single linear stepwise regression. The dynamic distribution of habitat patches over space and time, combined with changing patterns of resource utilisation and movement of L. raniformis, highlights the importance of incorporating both permanent and ephemeral habitat patches into conservation plans. Reductions in flood frequency and extent of ephemeral wetlands due to modified flooding regimes have the capacity to limit dispersal of this species, even when permanent waterbodies remain unchanged.

1999 ◽  
Vol 26 (5) ◽  
pp. 675 ◽  
Author(s):  
P. B. Whitaker ◽  
R. Shine

Encounters between humans and dangerously venomous snakes put both participants at serious risk, so the determinants of such encounters warrant attention. Pseudonaja textilis is a large fast-moving elapid snake responsible for most snakebite fatalities in Australia. As part of a broad ecological study of this species in agricultural land near Leeton, New South Wales, we set out to identify factors influencing the probability that a human walking in farmland would come into close proximity to a brownsnake. Over a three-year period, we walked regular transects to quantify the number and rate of snake encounters, and the proportion of snakes above ground that could be seen. The rate of encounters depended upon a series of factors, including season, time of day, habitat type, weather conditions (wind and air temperature) and shade (light v. dark) of the observers’ clothing. Interactions between factors were also important: for example, the effect of air temperature on encounter probability differed with season and snake gender, and the effect of the observers’ shade of clothing differed with cloud cover. Remarkably, even a highly-experienced observer actually saw <25% of the telemetrically monitored snakes that were known to be active (i.e. above ground) nearby. This result reflects the snakes’ ability to evade people and to escape detection, even in the flat and sparsely vegetated study area. The proportion of snakes that were visible was influenced by the same kinds of factors as described above. Most of the factors biasing encounter rates are readily interpretable from information on other facets of the species’ ecology, and knowledge of these factors may facilitate safer coexistence between snakes and people.


2009 ◽  
Vol 31 (3) ◽  
pp. 329 ◽  
Author(s):  
Tom Lewis ◽  
Peter J. Clarke ◽  
Ralph D. B. Whalley ◽  
Nick Reid

An assessment of the relative influences of management and environment on the composition of floodplain grasslands of north-western New South Wales was made using a regional vegetation survey sampling a range of land tenures (e.g. private property, travelling stock routes and nature reserves). A total of 364 taxa belonging to 55 different plant families was recorded. Partitioning of variance with redundancy analysis determined that environmental variables accounted for a greater proportion (61.3%) of the explained variance in species composition than disturbance-related variables (37.6%). Soil type (and fertility), sampling time and rainfall had a strong influence on species composition and there were also east–west variations in composition across the region. Of the disturbance-related variables, cultivation, stocking rate and flooding frequency were all influential. Total, native, forb, shrub and subshrub richness were positively correlated with increasing time since cultivation. Flood frequency was positively correlated with graminoid species richness and was negatively correlated with total and forb species richness. Site species richness was also influenced by environmental variables (e.g. soil type and rainfall). Despite the resilience of these grasslands, some forms of severe disturbance (e.g. several years of cultivation) can result in removal of some dominant perennial grasses (e.g. Astrebla spp.) and an increase in disturbance specialists. A simple heuristic transitional model is proposed that has conceptual thresholds for plant biodiversity status. This knowledge representation may be used to assist in the management of these grasslands by defining four broad levels of community richness and the drivers that change this status.


2006 ◽  
Vol 28 (2) ◽  
pp. 187 ◽  
Author(s):  
S. L. Radford ◽  
J. McKee ◽  
R. L. Goldingay ◽  
R. P. Kavanagh

In 1996, guidelines were produced for capture and radio-tracking protocols for koala (Phascolarctos cinereus) research within New South Wales (NSW). An integrated project commenced in 1998 to examine P. cinereus ecology and health status in Pine Creek State Forest. This project utilised intensive clinical and pathological assessment protocols on captured P. cinereus in combination with radio-tracking and ecological investigations. The methods used in this project were referred to the NSW Koala Research Committee (KRC) for review in mid 1999 due to the political profile of the study area. The KRC assessed the project protocols and reviewed the original guidelines incorporating some of the protocols used in the Pine Creek project. The outcome is a new set of protocols for P. cinereus research within NSW which are more explicit and restrictive than those applied to P. cinereus research elsewhere or to research on other species. In their current form the new guidelines require a substantial investment in time, equipment, personnel and finance; factors that may deter or restrict future, comprehensive ecological research on P. cinereus populations. They inadequately provide for some practices we believe important in minimising the invasiveness of P. cinereus capture. We propose amendments to the guidelines in the areas of personnel required, behavioural assessment, capture methods, processing safety and tracking frequency. We suggest that these amendments will render the guidelines more accessible to a broader range of projects, and easier to apply under field conditions while preserving the intent to maintain P. cinereus welfare and research best practice.


2012 ◽  
Vol 34 (1) ◽  
pp. 49 ◽  
Author(s):  
Lisa Warnecke ◽  
Gerhard Körtner ◽  
Chris J. Burwell ◽  
James M. Turner ◽  
Fritz Geiser

Since little information is available on the spatial ecology of small arid-zone marsupials, we used radio-tracking to investigate the small-scale activity patterns of three dasyurid species in semiarid Australia. Sminthopsis crassicaudata, Planigale gilesi and S. macroura were equipped with miniature radio-transmitters to monitor choice of resting sites and daily movements. Resting sites were located within an area of 1.27 ± 0.36 ha, 0.12 ± 0.02 ha and 3.60 ± 0.95 ha, respectively and individuals returned to previously used resting sites regularly. We also analysed scat samples of S. crassicaudata and P. gilesi, and identified Araneae, Hymenoptera and Orthoptera as the major prey taxa for both species. Our study presents the first radio-tracking-based information on movements for these species in semiarid habitat, which indicates that, over a period of several weeks, resting sites are situated within small and defined areas.


2005 ◽  
Vol 27 (2) ◽  
pp. 137 ◽  
Author(s):  
B Law ◽  
M Chidel ◽  
A Mong

We studied the eastern cave bat (Vespadelus troughtoni) in northern New South Wales to provide ecological information on roosts and foraging. Radio-tracking of five bats was supplemented with opportunistic visits to roosts over five years. One male was radio-tracked and its roost was within a corrugated iron roof cavity of a dairy. Maternity roosts were located in the overhangs of large sandstone caves usually containing a dome at the rear. Searches of nearby cliff-lines found that small caves, crevices and overhangs were not used as day-roosts. Nor did any radio-tagged bat roost in tree hollows. Colony size of one tight roosting cluster was estimated as 240 individuals. Radio-tagged bats frequently switched roosts, while opportunistic visits over a five-year period often found caves unoccupied. Most movements between roosts were within 1.5 km, although one female moved about 3.75 km between roosts. One radiotagged female shifted roost to beneath the corrugated iron of a farm-shed that supported at least 50 bats, predominantly females with young. Observations of foraging radio-tagged and lighttagged bats were frequent along a stream lined with trees, but surrounded by cleared paddocks. Foraging was observed in the air space above the creek, interspersed with occasional rapid flights across paddocks (> 500 m). We suggest that a key requirement for V. troughtoni in the rural landscape is the presence of native vegetation in close proximity to roosts, although extensive forested areas may not be required. Education of local communities about the sensitivity of these bats at cave roosts would be an important contribution to their conservation.


Energies ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 225 ◽  
Author(s):  
Pedro Branco ◽  
Francisco Gonçalves ◽  
Ana Cristina Costa

The fastest-growing renewable source of energy is solar photovoltaic (PV) energy, which is likely to become the largest electricity source in the world by 2050. In order to be a viable alternative energy source, PV systems should maximise their efficiency and operate flawlessly. However, in practice, many PV systems do not operate at their full capacity due to several types of anomalies. We propose tailored algorithms for the detection of different PV system anomalies, including suboptimal orientation, daytime and sunrise/sunset shading, brief and sustained daytime zero-production, and low maximum production. Furthermore, we establish simple metrics to assess the severity of suboptimal orientation and daytime shading. The proposed detection algorithms were applied to a set of time-series of electricity production in Portugal, which are based on two periods with distinct weather conditions. Under favourable weather conditions, the algorithms successfully detected most of the time-series labelled with either daytime or sunrise/sunset shading, and with either sustained or brief daytime zero-production. There was a relatively low percentage of false positives, such that most of the anomaly detections were correct. As expected, the algorithms tend to be more robust under favourable rather than under adverse weather conditions. The proposed algorithms may prove to be useful not only to research specialists, but also to energy utilities and owners of small- and medium-sized PV systems, who may thereby effortlessly monitor their operation and performance.


1996 ◽  
Vol 6 (3) ◽  
pp. 145 ◽  
Author(s):  
MS Speer ◽  
LM Leslie ◽  
JR Colquhoun ◽  
E Mitchell

Southeastern Australia is particularly vulnerable to wildfires during the spring and summer months, and the threat of devastation is present most years. In January 1994, the most populous city in Australia, Sydney, was ringed by wildfires, some of which penetrated well into suburban areas and there were many other serious fires in coastal areas of New South Wales (NSW). In recent years much research activity in Australia has focussed on the development of high resolution limited area models, for eventual operational prediction of meteorological conditions associated with high levels of wildfire risk. In this study, the period January 7-8, 1994 was chosen for detailed examination, as it was the most critical period during late December 1993/early January 1994 for the greater Sydney area. Routine forecast guidance from the Australian Bureau of Meteorology's operational numerical weather prediction (NWP) models was very useful in that both the medium and short range models predicted synoptic patterns suggesting extreme fire weather conditions up to several days in advance. However, vital information of a detailed nature was lacking. A new high resolution model was run at the operational resolution of 150 km and the much higher resolutions of 25 km and 5 km. The new model showed statistically significant greater skill in predicting details of wind, relative humidity and temperature patterns both near the surface and above the boundary layer. It also produced skilful predictions of the Forest Fire Danger Index.


2010 ◽  
Vol 19 (1) ◽  
pp. 76-80 ◽  
Author(s):  
Edith M.C. Lau ◽  
Bill G. Gillespie ◽  
Lisa Valenti ◽  
Dianne O'Connell

1991 ◽  
Vol 18 (4) ◽  
pp. 463 ◽  
Author(s):  
HJ Spencer ◽  
C Palmer ◽  
K Parry-Jones

Results from a long-term radio-tracking study of pteropodid fruit-bats are reported. Grey-headed fruit bats (Pteropus poliocephalus) captured from seven colonies in eastern New South Wales, Australia, were fitted with collar-mounted radio transmitters to permit their movements to be monitored over the following year. The sheepskin-lined leather collars were well tolerated by the bats over periods of 6-18 months. Bats moved between major colony sites for distances of up to 750 km, with movements occurring in both northerly and southerly directions. One bat from Lismore had a feeding range of 25 km, whereas in Sydney bats flew up to 17 km each night to feeding sites. There was considerable interchange between bats in adjacent colonies.


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