Population Analysis and Modelling Unit

Box Hill South, Australia

Population Analysis and Modelling Unit

Box Hill South, Australia
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Ellis M.V.,Population Analysis and Modelling Unit | Taylor J.E.,Australian Catholic University
Australian Zoologist | Year: 2014

Loss and fragmentation of the native vegetation of the Central Western Plains of New South Wales was followed by declines of woodland-dependent species. Drought is likely to have further suppressed many animal populations. Here we report on changes in woodland bird reporting rates between surveys in 2005-2009 (drought declared period) and surveys in 2010-2013 following the drought-breaking rains of 2010. By 2013 the number of species detected per survey had just recovered to the level of surveys in 2005/6.The 2013 species composition of the region was similar to that recorded in the 2005-2009 drought surveys, with half of the small insectivorous and nectarivorous woodland birds remaining rare and restricted.Woodland remnants in the landscape continued to be dominated by the same, usually large, species of birds, but reporting rates of 13 of the 15 most common species declined. Conversely, several smaller, foliage gleaning passerines had higher reporting rates post-drought, with Striated Pardalote and Western Gerygone becoming two of the most frequendy recorded species. Taxonomic and life history attributes usually did not predict population changes for species post-drought, with the only feeding guild showing a consistent trend being the mistletoe specialists, with only two species. Even after the drought-breaking rains of 2010, there appears to be a reduced vigour in these woodland landscapes.

Ellis M.,Western Region Biodiversity Conservation Project | Ellis M.,Population Analysis and Modelling Unit
Australian Zoologist | Year: 2013

As part of regional biological surveys 51 sites were established in the rangelands of western New South Wales, Australia.To investigate the impacts of pit size, drift fence material and fence configuration on capture rates small vertebrates each site consisted of two 201 bucket traps with two configurations of flyscreen drift fences (transparent), two PVC pipe traps with the same two configurations of fencing, and two PVC pipe traps with dampcourse (opaque) in the same two configurations. PVC pipe traps caught more species and individuals than 20 1 plastic buckets (41 versus 38 species, 232 versus 208 captures, respectively when pooled across the two fence configurations using flyscreen). Four fences radiating in a cross pattern from a pit caught 41% more individuals, but not the number of species, compared to two radiating fences (463 versus 328 captures) when pooled across the two pit types and the two fence materials. Capture success was influenced by the fence material used, with mammals being more often captured when using flyscreen fences and reptiles more often when using dampcourse fences (28 versus 18 and 256 versus 283 captures, respectively).The arboreal skink Cryptoblepharus carnabyi showed the strongest difference in the number of captures between flyscreen (27 captures) and dampcourse (67 captures) when used in conjunction with PVC pipe. If a broad biological survey is to be undertaken then a mixture of pit sizes and fence materials is warranted within the survey design. If population studies are the primary concern, then consideration of the benefits of increased capture rates versus costs of installing additional fencing needs to be including in the planning of the field sampling.

Taylor J.E.,Australian Catholic University | Ellis M.V.,Population Analysis and Modelling Unit | Rayner L.,Australian Catholic University | Rayner L.,Australian National University
Forest Ecology and Management | Year: 2014

Conservation planning for many fauna relies on an ability to predict length of time lags to production of habitat requirements in restoration plantings or with natural regeneration. One key consideration is the growth rate of dominant trees, as tree age and size are linked to characteristics that provide fauna habitat, such as canopy cover, tree hollows and coarse woody debris. In this study we examined growth rate and mortality of Eucalyptus species for all individuals with diameter at breast height (DBH). ≥. 15. cm on forty one-ha sites in temperate semi-arid woodland in eastern Australia. Over five years (2008-2013) encompassing drought and flood, mean growth was <2.5. cm in DBH. Mixed effects models indicated that growth rate differed among species, and decreased with increasing senescence and greater initial foliage projective cover on the site. There was no link between initial tree DBH and growth rate for most species. Growth in DBH was similarly variable in large and small trees. Consequently increases in cross-sectional area, and hence biomass accumulation, are likely to be faster in larger trees. Growth of E. microcarpa, E. camaldulensis, E. blakelyi and E. conica did not significantly differ but was faster than that of E. populnea and E. melliodora. The random factors site and tree identity (for multi-stemmed trees) explained around 10% and 30% of the overall variability in growth rate respectively. Twelve trees (~1%) died and 4 live trees were cut down and removed. Five (6.5%) of the 75 standing dead trees present in 2008 collapsed, and a further eight (10.5%) were cut down and removed by people. Forty saplings of four species with DBH. <. 15. cm in 2008 grew to DBH. ≥. 15. cm by 2013, equating to a recruitment rate of <4%, but this occurred on only nine of the 40 sites. Our study suggests mortality rate is being met by recruitment rate at the regional scale, but recruitment was extremely patchy and may result in site scale extinctions. The growth rates measured indicate that trees planted to create fauna habitat may take centuries to reach sizes that would contain large nesting or roosting hollows for fauna. © 2014 .

Ellis M.V.,Western Zone Conservation and Planning Unit | Ellis M.V.,Population Analysis and Modelling Unit | Taylor J.E.,Australian Catholic University | Rayner L.,Australian National University
Ecological Management and Restoration | Year: 2015

Hollows, also known as tree cavities, are critical to the survival of many animal species but are too poorly mapped across landscapes to allow for their adequate consideration in regional planning. Managing cost is important, so we tested whether freely available satellite-derived foliage projective cover and field-measured stand attributes could be used separately or combined to predict tree hollow abundance in relictual Australian temperate woodlands. Satellite-derived foliage projective cover revealed variation in woody vegetation densities both within mapped woodland remnants and cleared areas of the agricultural matrix. Plot-based field assessment of the actual number of hollows in each one-hectare site (n = 110 sites) revealed a relationship with foliage cover. Improvement of the model was achieved if site-based estimates of the proportion of the canopy due to Eucalyptus species and the number of mature trees per hectare were included. Remotely sensed foliage cover can improve on traditional vegetation mapping for predicting hollow-bearing tree and hollow abundances at landscape scales when managing hollow-dependent fauna habitat across relictual woodlands in temperate Australian agricultural landscapes. At finer scales, the addition of other predictors is necessary to raise the accuracy of the predicted hollow densities. © 2015 Ecological Society of Australia and Wiley Publishing Asia Pty Ltd.

Ellis M.V.,Population Analysis and Modelling Unit | Bedward M.,Population Analysis and Modelling Unit | Bedward M.,University llongong
Ecosphere | Year: 2014

Drift fences with traps are commonly used for ecological research and survey. Field studies have examined the effectiveness of selected fence layouts, but comprehensive field testing is impractical. We applied a simulation approach to investigate how the interaction of fence layout and animal movement type influence fence encounter rates. A range of fence layouts, varying in spacing and configuration, were chosen based on common field practices and recommendations in the literature. Animal movement patterns ranged from meandering (Brownian) to highly directional over distances of 10 to 500 m.We found that fences in short, straight, widely spaced arrangements would be encountered more frequently by highly mobile animals than the same amount of fence in complex or continuous configurations. The dispersed arrangement was encountered just as often by animals with more limited movement patterns as were closer spaced fences. Consequently, for broad-scale surveys, as opposed to studies on individuals' movements and microhabitat use, we recommend spacing trap/fence units in relation to the movement abilities of the most mobile species being sought. For studies that require intense point sampling, additional fencing should increase the total rate that animals encounter fences at a point but the increase will not be proportional to the additional fencing used. The software is provided to allow for other configurations of fences and movement patterns to be investigated. © 2014 Ellis and Bedward.

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