Habitat requirements of the yellow-footed antechinus (Antechinus flavipes) in box - ironbark forest, Victoria, Australia

2008 ◽  
Vol 35 (2) ◽  
pp. 128 ◽  
Author(s):  
Luke T. Kelly ◽  
Andrew F. Bennett
Keyword(s):  
Forest Structure ◽  
Dry Forest ◽  
Habitat Requirements ◽  
Theoretic Approach ◽  
Logistic Regression Models ◽  
Explanatory Variables ◽  
Rock Cover ◽  
Eastern Australia ◽  
Large Trees ◽  
Information Theoretic Approach

Understanding the habitat requirements of a species is critical for effective conservation-based management. In this study, we investigated the influence of forest structure on the distribution of the yellow-footed antechinus (Antechinus flavipes), a small dasyurid marsupial characteristic of dry forests on the inland side of the Great Dividing Range, Australia. Hair-sampling tubes were used to determine the occurrence of A. flavipes at 60 sites stratified across one of the largest remaining tracts of dry box–ironbark forest in south-eastern Australia. We considered the role of six potential explanatory variables: large trees, hollow-bearing trees, coppice hollows, logs, rock cover and litter. Logistic regression models were examined using an information-theoretic approach to determine the variables that best explained the presence or absence of the species. Hierarchical partitioning was employed to further explore relationships between occurrence of A. flavipes and explanatory variables. Forest structure accounted for a substantial proportion of the variation in occurrence of A. flavipes between sites. The strongest influence on the presence of A. flavipes was the cover of litter at survey sites. The density of hollow-bearing trees and rock cover were also positive influences. The conservation of A. flavipes will be enhanced by retention of habitat components that ensure a structurally complex environment in box–ironbark forests. This will also benefit the conservation of several threatened species in this dry forest ecosystem.

Habitat selection by nesting and brood-rearing sharp-tailed grouse

2009 ◽  
Vol 87 (4) ◽  
pp. 326-336 ◽  
Author(s):  
Alicia D. Goddard ◽  
Russell D. Dawson ◽  
Michael P. Gillingham
Keyword(s):  
Spatial Scales ◽  
Conditional Logistic Regression ◽  
Habitat Type ◽  
Theoretic Approach ◽  
Information Theoretic ◽  
Logistic Regression Models ◽  
Brood Rearing ◽  
Shrub Steppe ◽  
Information Theoretic Approach ◽  
Selection Of

Breeding success is a critical component of population stability and is often influenced by the habitats used during the breeding season. Current hypotheses suggest that sharp-tailed grouse ( Tympanuchus phasianellus (L., 1758)) select nest and brood-rearing habitats that provide both lateral and overhead cover to avoid detection by predators. We examined the selection of nesting and brood-rearing habitats of sharp-tailed grouse at three spatial scales (landscape, patch, and site) in northeastern British Columbia using standard and conditional logistic regression models and an information–theoretic approach. At the patch and site scales, our results validate our predictions, as nesting females selected shrub–steppe habitats, greater shrub and grass cover, taller vegetation, and greater residual vegetation compared with random sites. Brood-rearing females selected for agricultural habitats during the early brood-rearing period (0–14 days), but did not show selection of any habitat type or site attribute during the late brood-rearing period (15–49 days). We suggest that the selection of shrub-dominated habitats by nesting females supports the hypothesis that females select sites and habitats that maximize concealment. We further suggest that selection of shrub-dominated habitat is occurring in response to changes in habitat conditions and availability, as natural grassland communities have diminished across the landscape.

scholarly journals Forest Edges Negatively Affect Golden-Cheeked Warbler Nest Survival

The Condor ◽  
2007 ◽  
Vol 109 (3) ◽  
pp. 628-637
Author(s):  
Rebecca G. Peak
Keyword(s):  
Breeding Season ◽  
Nest Survival ◽  
Forest Edge ◽  
Breeding Habitat ◽  
Conservation Strategies ◽  
Edge Density ◽  
Parameter Estimates ◽  
Theoretic Approach ◽  
Explanatory Variables ◽  
Information Theoretic Approach

Abstract Abstract. I used an information-theoretic approach to determine support for hypotheses concerning the effects of edge and temporal factors on Golden-cheeked Warbler (Dendroica chrysoparia) nest survival on Fort Hood Military Reservation, Texas, during 2003–2006. I predicted that nest survival would be greater earlier in the breeding season than later in the breeding season, in areas with less forest edge than in areas with more forest edge, and during the laying and incubation stages than during the nestling stage. I used the logistic-exposure method to model nest survival as a function of the explanatory variables and to produce model-based estimates of daily and period survival. The overall daily survival rate was 0.96 (95% CI: 0.94, 0.97) and overall period survival was 0.34 (95% CI: 0.23, 0.46). Forest edge density had the strongest effect on nest survival. Nest survival decreased as forest edge density increased. Period survival tended to decrease as the breeding season progressed, but the 95% confidence intervals of the model-averaged parameter estimates overlapped. These results demonstrate that effective conservation strategies designed to provide high-quality breeding habitat for this endangered species should include measures to reduce predation by edge-adapted predators.

Predicting the occurrence of the quokka, Setonix brachyurus (Macropodidae:Marsupialia), in Western Australia's northern jarrah forest

2007 ◽  
Vol 34 (3) ◽  
pp. 194 ◽  
Author(s):  
Matt W. Hayward ◽  
Paul J. de Tores ◽  
Michael J. Dillon ◽  
Peter B. Banks
Keyword(s):  
Linear Models ◽  
Parameter Estimate ◽  
Weight Of Evidence ◽  
Theoretic Approach ◽  
Age Classes ◽  
Jarrah Forest ◽  
Explanatory Variables ◽  
Model Average ◽  
Information Theoretic Approach ◽  
Fox Control

The quokka, Setonix brachyurus, is a medium-sized, macropodid marsupial that is endemic to south-western Australia. It has declined markedly in its distribution and abundance since the early 1930s and is listed as vulnerable under IUCN criteria. The presence or absence of quokka populations at 66 sites in the northern jarrah forest of Australia was investigated using generalised linear models (GLM). We hypothesised that fox control and the presence of a mosaic of post-fire seral stages within Agonis linearifolia swamp vegetation were important in predicting the presence of quokkas. The number of poison meat baits delivered per hectare, the average number of years since the swamps burnt and the number of post-fire age classes within the swamps (mosaic value) were used as explanatory variables. Two models had substantial support (ΔAICc < 2), with the best approximating model including the variables ‘baiting’ and ‘swamp age’, and the second-best model including the additional variable ‘swamp mosaic value’. The two best models had Akaike weights (weight of evidence as being the best model of the data) of 0.465 and 0.308 respectively. We used an information-theoretic approach and multimodel inference to determine the best approximating model of baiting, swamp age and swamp mosaic, and Akaike weights to assess model fit and to rank variable importance. Baiting had a model average parameter estimate of 98, swamp age 79 and a mosaic of swamp age classes 42, implying that baiting was more than twice as important as the number of swamp ages classes at a site in predicting the occurrence of quokkas. Evidence from our analysis therefore supports previous studies that concluded that continued fox control and the maintenance of a mosaic of early seral stage (<10 years since fire) and long unburnt habitat (>19 years since fire) are essential for its conservation.

scholarly journals Forest fuel bed ignitability under marginal fire weather conditions in Eucalyptus forests

2019 ◽  
Vol 28 (3) ◽  
pp. 198 ◽  
Author(s):  
Jane G. Cawson ◽  
Thomas J. Duff
Keyword(s):  
Weather Conditions ◽  
Field Method ◽  
Fire Weather ◽  
Theoretic Approach ◽  
Prescribed Burns ◽  
Information Theoretic ◽  
Logistic Regression Models ◽  
Spatial Coverage ◽  
Information Theoretic Approach ◽  
Fuel Moisture Content

Fires burning under marginal fire-weather conditions tend to be patchy in terms of their spatial coverage. This patchiness is partially driven by variability in the ignitability of the fuel bed. An understanding of fuel-bed ignitability through space and time would help fire managers to more effectively carry out prescribed burns to achieve desired levels of burn coverage in Eucalyptus forests. We sought to identify the key fuel-bed attributes influencing ignitability under marginal weather conditions. We recorded ignition successes and failures at 45 points within 5 operational prescribed burns and used the data to build logistic regression models to predict the probability of ignition as a function of fuel-bed attributes. Models were ranked using an information theoretic approach. The four highest ranked models explained 48–54% of the variance in ignitability. Surface fine-fuel moisture content (FFMC) and overall fuel hazard (i.e. fuel arrangement) were the strongest predictors of ignitability, occurring in all four highest ranking models. Both surface FFMC and overall fuel hazard were negatively related to ignition likelihood, contradicting a commonly assumed positive relationship between fuel hazard and flammability. Our field method to measure ignition success could be applied across more prescribed burns to develop operationally useful models of ignitability.

Quantifying wildfire growth rates using smoke plume observations derived from weather radar

2018 ◽  
Vol 27 (8) ◽  
pp. 514 ◽  
Author(s):  
Thomas J. Duff ◽  
Derek M. Chong ◽  
Trent D. Penman
Keyword(s):  
Real Time ◽  
Quantitative Methods ◽  
Radar Data ◽  
Rate Of Change ◽  
Theoretic Approach ◽  
Weather Radars ◽  
Time Estimates ◽  
Eastern Australia ◽  
Fire Area ◽  
Information Theoretic Approach

Fast-moving wildfires can result in substantial losses of infrastructure, property and life. During such events, real-time intelligence is critical for managing firefighting activities and public safety. The ability of fixed-site weather radars to detect the plumes from fires has long been recognised; however, quantitative methods to link properties of radar observed plumes to fire behaviour are lacking. We investigated the potential for weather radars to provide real time estimates of the growth of large fires in south-eastern Australia. Specifically, we examined whether the rate of change in fire area could be approximated using the change in volume represented by radar returns. We evaluated a series of linear mixed-effects models predicting fire-area growth using radar data representing a range of dBZ thresholds and search volumes. Models were compared using an information–theoretic approach. Radar return volume was found to be a robust predictor of fire-area change. The best model had a minimum threshold of 10 dBZ and a search radius of 60 km (R2 = 0.64). Fire area and radar relationships did not vary significantly between radar stations, suggesting broad applicability beyond the dataset. Further development of the use of weather radars for wildfire monitoring could yield substantial benefits because of their high frequency of scan and broad coverage over many populated areas.

scholarly journals Environmental factors affecting the wintering raptor community in Armenia, Southern Caucasus

2021 ◽  
Author(s):  
Gianpasquale Chiatante ◽  
Michele Panuccio
Keyword(s):  
General Pattern ◽  
Abundant Species ◽  
Theoretic Approach ◽  
Factors Affecting ◽  
Milvus Migrans ◽  
Gyps Fulvus ◽  
Black Kite ◽  
Southern Caucasus ◽  
And Migration ◽  
Information Theoretic Approach

AbstractThe species–habitat relationships can change during the year because of the seasonality of resources. Therefore, the investigation of habitat use by animals in each season plays a fundamental role in their conservation. The main aim of this research was to investigate the raptor community that spends the winter in Armenia, southern Caucasus, and to explore its relationship with environmental features, such as land use and topography. During January 2012, we collected data by carrying out 15 roadside counts along which we calculated three community parameters: the relative abundance, the species richness, and the species diversity. Then, we carried out a multiple linear regression with the Information-Theoretic Approach, to explain the relationship between the parameters and environmental variables. Besides, we computed a Canonical Correspondence Analysis (CCA) between the species and the environment around their observations. As a general pattern, the community was associated with permanent crops, maybe because of their heterogeneity, which in turn allows them to support higher densities of prey during the winter. The most abundant species was the Black Kite (Milvus migrans), followed by the Common Kestrel (Falco tinnunculus) and the Griffon Vulture (Gyps fulvus). To our knowledge, this is one of the first studies investigating the wintering raptor community in the Caucasus, with raptors generally studied in this area during the breeding season and migration.

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