Academic literature on the topic 'Ninox strenua'

The diet of powerful owls (Ninox strenua) living at Christmas Hills, 35 km north-east of Melboume, was examined by analysis of 686 regurgitated pellets collected over two years. Mammalian prey was found in 89%, insects in 13%, vegetation in 11% and birds in 10% of the pellets. Of the mammals, common ringtail possums occurred most frequently in the pellets over the year. There was no seasonal difference in the frequency of occurrences of common ringtail possums and sugar gliders in pellets. However, common brushtail possums were more likely to be taken in spring than in the other seasons. More adult common ringtail possums were taken as prey than were other age classes over the year, except in summer when high numbers of young were consumed by the owls.

This study identified and compared the abundance and detectability of owls and other nocturnal birds, over 1 year, in an urban parkland of a Brisbane suburb to a peri-urban/hinterland/rainforest site 27km away. Five owl species were detected, but only at the peri-urban/hinterland/rainforest site, they were powerful owl Ninox strenua, southern boobook Ninox boobook, sooty owl, Tyto tenebricosa, masked owl Tyto novaehollandiae and barn owl Tyto alba. A single southern boobook was detected outside the study, at the urban site. The tawny frogmouth Podargus strigoides was only detected at the urban site whereas the plumed frogmouth Podargus ocellatus plumiferus was only detected at the rainforest site. The bush stone-curlew Burhinus grallarius was the most frequently detected nocturnal species, yet we discuss its recent decline in Brisbane. Incidentally recorded mammals, reptiles, frogs and diurnal birds are given. The rainforest site had more scansorial mammals whereas the urban site had more possums, dogs and cats.

The diet of Powerful Owls (Ninox strenua) living at Christmas Hills, 35km north-east of Melbourne was examined by analysis of 686 regurgitated pellets collected over two years. An aid was also developed to help identify potential mammalian prey species based on hair and skeletal characteristics. The following features were found to be most useful in distinguishing between the three species of arboreal marsupials - Common Ringtail Possum (Pseudocheirus peregrinus), Common Brushtail Possum (Trichosurus vulpecula) and Sugar Glider (Petaurus breviceps): - Cross-sectional width of primary guard hairs. - The size and shape of the nasal, frontal, parietal and squamosal bones of the skull. - Dentition. The size and shape of the upper incisor, canine and premolar teeth. The size and shape of the lower incisor and premolar teeth. - The size of the humerus. The Sugar Glider has a much smaller humerus than that of the Common Ringtail Possum and the Common Brushtail Possum. In the Common Brushtail Possum the entepicondyle ends in a very sharp point but the Common Ringtail Possum this point is not as sharp. - The Common Ringtail Possum’s femur has a very prominent trochanter which projects further than that in the Common Brushtail Possum. The femur of the Sugar Glider is distinguished by having a very large depression between the condyle and the trochanter. - The Common Brushtail Possum’s scapula has a narrower lower blade (relative to length) than that in the Common Ringtail Possum. The scapula of the Sugar Glider is smaller in size than that of the other two possums.The pelvic girdle Of the Common Brushtail Possum has a much wider ischium than those of the Common Brushtail Possum and the Sugar Glider. The ilium of the Sugar is much narrower and smaller than that of the other two possums Mammalian prey was found in 89%, insects in 13% and birds in 10% of the pellets. Of the mammals, Common Ringtail Possums occurred most frequently in the pellets over the year. There was no seasonal difference in the frequency of occurrence of Common Ringtail Possums and Sugar Gliders in pellets. However, Common Brushtail Possums were more likely to be taken in spring than in the other seasons. More adult Common Ringtail Possums were taken as prey than were other age classes over the year, except in summer when high numbers of young were consumed by the owls. The habitat of the Powerful Owl was examined by ground surveys and spotlight surveys in sixteen sites within the Warrandyte-Kinglake Nature Conservation Link. Four categories of survey sites were chosen with the following features. Category A - Sites with a dense understorey of shrubs and small trees, as well as many old trees (>10/ha) which might be suitable for nest hollows. Category B - Sites which lacked a dense understorey of shrubs and small trees and containing few or no old trees suitable for nest hollows. Category C - Sites with a dense understorey of shrubs and small trees but containing few or no old trees suitable for nest hollows. Category D - Sites which lacked a dense understorey of shrubs and small trees but having old trees (>10/ha) which might be suitable for nest hollows. High prey densities strongly correlated with the presence of hollows at these sites. In the light of the results, management recommendations were made for the future conservation of the Powerful Owls living at Christmas Hills. The following recommendations were particularly important: 1. Cleared or semi - cleared land within the Warrandyte Kinglake Nature Conservation Link be revegetated using indigenous species of eucalypts and waffles in order to provide a contiguous native forest corridor for the movement of possums and gliders between the Yarra River Valley and the Kinglake Plateau. 2. Continued planting of Eucalyptus spp. and Acacia spp. in the forested areas of the Warrandyte-Kinglake Nature Conservation Link. 3. Continued protection of healthy living trees to provide a continuous supply of hollow trees. 4. No falling of dead standing trees for firewood collecting as these can provide nest hollows for prey species of the Powerful Owl.

In this research I investigated ecological attributes of Powerful Owls (Ninox strenua) in a continuum of habitats throughout the Yarra Valley corridor of Victoria, Australia. These habitats ranged from a highly urbanized parkland (the Yarra Valley Metropolitan Park) to a relatively undisturbed closed forest (Toolangi State Forest). Different aspects of the owls' ecology were investigated at six sites to determine whether their behaviour changed when they occupied habitats with different levels of urbanization and disturbance. The ecological attributes investigated were habitat utilization and habitat requirements (for both roosting and nesting), adult behaviour (through radio-tracking), juvenile behaviour and dispersal (through radio tracking), diet (through analysing regurgitated food pellets) and breeding success rates. A number of methods were used to capture adult Powerful Owls. These are described and their effectiveness discussed. The types of radio-transmitters and colour bands used for identification of owls are also described. The results showed that Powerful Owls are present and successfully breed in urban and suburban areas and that they can tolerate moderate levels of disturbance. However, Powerful Owls do require sites with high prey densities, roost trees and trees with suitable breeding hollows. In comparison with Powerful Owls living elsewhere in forests, the urban owls displayed higher tolerance levels to disturbance and were less selective in terms of habitat usage and diet. Home range sizes of urban Powerful Owls also appeared much smaller than those of the forest-dwelling Powerful Owls. This is probably due to the high prey densities in the urban areas. The ecology of the Powerful Owl is compared with that of two owl species from North America, the Northern Spotted Owl (Strix occidentalis caurind) and the Great Horned Owl (Bubo virginianus). In particular, I compared the similarities and differences in habitat requirements and breeding successes in different habitats for the three species. Overall, it would appear that urban areas can support Powerful Owls providing some old-growth trees are maintained to provide nest hollows. Implications for the long-term management of Powerful Owls in urban areas are also discussed.

This thesis utilises passive acoustic monitoring as a framework to study Powerful Owls (Ninox strenua) in south-east Queensland. The study quantitively describes the vocalisations of adult and chick Powerful Owls and utilises open-source machine learning software to create automated species recognition tools for use in citizen science programs. The results indicate that call characteristics historically used to sex adult Powerful Owls are likely unreliable. Testing of the automated call recognisers resulted in highly promising outcomes, which suggests that they are likely to be valuable tools for future study.

Over half of the world’s human population are living within an urban environment. As a result, urbanisation of the natural landscape has increased, involving extensive land use change, and reducing the ecological resilience of species living within these complex environments. Habitat fragmentation and isolation caused by urbanisation can reduce the landscape connectivity of the ecological network. Landscape connectivity between habitat patches is critical to sustain genetic diversity, migration and sufficient territories for many species within complex landscapes. Therefore to increase ecological resilience for species within an urban system increased effort is required on applying conservation measures to natural areas within an urban environment. The powerful owl (Ninox strenua) is one of many species affected by increasing urbanisation and land use change. It is the largest owl species in Australia and considered vulnerable within New South Wales. It is a habitat specialist that requires high density woody vegetation cover for both foraging (main prey being arboreal marsupials) and nesting, and has an extensive home-range. Though previous research has acknowledged the effect urbanisation will have on the owl, none have previously gone into its dispersal habitat requirements and the influence landscape connectivity will have on its dispersal and occurrence throughout an urbanised system. Hence this study has investigated the influence woody vegetation connectivity has on the dispersal and occurrence of the powerful owl within the Greater Sydney Region, NSW. The study is split into two main sections, 1) Mapping woody vegetation and 2) Analysing and evaluating landscape connectivity for the powerful owl. To generate a land cover map of the study area, high resolution aerial photographs and an object oriented analysis in combination with a classification tree was used. The land cover map produced for the study area achieved high overall classification accuracy (>85%) and for the woody vegetation class (>90%). To analyse landscape connectivity the circuit theory was used. The circuit theory takes into account all possible pathways the owl could potentially use for dispersal depending on the permeability and resistance of the landscape. Resistance layers were developed from the woody vegetation land cover map and other environmental or anthropogenic features which may facilitate or prevent dispersal. A novel approach to evaluate the connectivity surfaces with species distribution modelling was developed using presence data of powerful owl observations. Woody vegetation connectivity was determined to have a critical effect on dispersal between habitat patches for the powerful owl. Sensitivity to disturbance of its dispersal habitat was explored, with the results indicating high sensitivity to disturbance of its dispersal habitat. Therefore increasing land use change within the Sydney area will potentially decrease the available habitat for dispersal and reduce the powerful owl’s ecological resilience to future disturbance.