We explored the effects of land-cover configuration, body size and trophic diversity in determining avian species richness on Prince Edward Island, Canada. Data on avian species richness were obtained from the Maritim...We explored the effects of land-cover configuration, body size and trophic diversity in determining avian species richness on Prince Edward Island, Canada. Data on avian species richness were obtained from the Maritime Breeding Bird Atlas data. Prince Edward Island was divided into 97 sampling cells of 10 × 10 km. Land-cover metrics were calculated using a forest inventory database, Fragstats and ArcView version 8.1. The relationships between avian species richness and explanatory variables were explored using correlation analysis, mixed forward-backward stepwise analysis, generalized linear models and Akaike’s information criterion. Models predicted between 27% and 63% of the variability in species richness, attributing substantial explanatory power to both the average body size and the range of body size spanned by the avian community. The body-size frequency distribution showed that avian communities were dominated by species weighing between 50 and 80 g. Habitat metrics associated with forests were more important to the avifauna than those related to agriculture. Avian species richness also decreased with both the fragmentation and isolation of wetlands. The total area covered by the human infrastructure land-cover and its subdivision were also important. Clearly, body size plays a key role in determining the diversity of birds on Prince Edward Island. In particular, species weighing 50 - 80 g appear to have sufficient resources to be successful on Prince Edward Island’s landscapes. Our findings also highlighted the importance of controlling the expansion of human infrastructure and both the fragmentation and reduction in size of wetlands to maintain avian species richness patterns.展开更多
Background: Eurasian Sparrowhawks(Accipiter nisus) increasingly represent successful city-dwellers. Thereby, a rich food supply indicated by high numbers of small birds is believed to be the key driver for this bird-e...Background: Eurasian Sparrowhawks(Accipiter nisus) increasingly represent successful city-dwellers. Thereby, a rich food supply indicated by high numbers of small birds is believed to be the key driver for this bird-eating raptor species to settle in urban environments. However, as small passerine birds show particularly strong antipredator responses, sparrowhawks may not simply focus on patches of highest prey densities, but rather respond strategically to prey behavior, raising the importance of other parameters in determining the occurrence within urban landscapes.Methods: To deepen our knowledge on habitat requirements of urban sparrowhawks, bird surveys were carried out during winter between December 2005 and January 2017 in 36 city parks in Vienna, Austria. Besides food supply also park size, canopy heterogeneity and the connectivity with other green spaces were considered.Results: Occurrence of sparrowhawks was positively affected by increasing park size, prey density and the interaction between both. Bird feeder density and park connectivity with other green spaces were of minor importance in explaining the presence of this species. Canopy heterogeneity didn't affect city park occupancy by Eurasian Sparrowhawks.Conclusions: Our results suggest that large city parks, particularly when characterized by high prey densities, substantially contribute to protect and preserve ecologically important bird species such as raptors within the urban environment—a landscape already struggling with biodiversity losses and functional homogenization.展开更多
In this paper, a method to design bird-strike-resistant aircraft structures is presented and illustrated through examples. The focus is on bird strike experiments and simulations. The explicit finite element software ...In this paper, a method to design bird-strike-resistant aircraft structures is presented and illustrated through examples. The focus is on bird strike experiments and simulations. The explicit finite element software PAM-CRASH is employed to conduct bird strike simulations, and a coupled Smooth Particles Hydrodynamic（SPH） and Finite Element（FE） method is used to simulate the interaction between a bird and a target structure. The SPH method is explained, and an SPH bird model is established. Constitutive models for various structural materials, such as aluminum alloys, composite materials, honeycomb, and foam materials that are used in aircraft structures,are presented, and model parameters are identified by conducting various material tests. Good agreements between simulation results and experimental data suggest that the numerical model is capable of predicting the dynamic responses of various aircraft structures under a bird strike,and numerical simulation can be used as a tool to design bird-strike-resistant aircraft structures.展开更多
文摘We explored the effects of land-cover configuration, body size and trophic diversity in determining avian species richness on Prince Edward Island, Canada. Data on avian species richness were obtained from the Maritime Breeding Bird Atlas data. Prince Edward Island was divided into 97 sampling cells of 10 × 10 km. Land-cover metrics were calculated using a forest inventory database, Fragstats and ArcView version 8.1. The relationships between avian species richness and explanatory variables were explored using correlation analysis, mixed forward-backward stepwise analysis, generalized linear models and Akaike’s information criterion. Models predicted between 27% and 63% of the variability in species richness, attributing substantial explanatory power to both the average body size and the range of body size spanned by the avian community. The body-size frequency distribution showed that avian communities were dominated by species weighing between 50 and 80 g. Habitat metrics associated with forests were more important to the avifauna than those related to agriculture. Avian species richness also decreased with both the fragmentation and isolation of wetlands. The total area covered by the human infrastructure land-cover and its subdivision were also important. Clearly, body size plays a key role in determining the diversity of birds on Prince Edward Island. In particular, species weighing 50 - 80 g appear to have sufficient resources to be successful on Prince Edward Island’s landscapes. Our findings also highlighted the importance of controlling the expansion of human infrastructure and both the fragmentation and reduction in size of wetlands to maintain avian species richness patterns.
文摘Background: Eurasian Sparrowhawks(Accipiter nisus) increasingly represent successful city-dwellers. Thereby, a rich food supply indicated by high numbers of small birds is believed to be the key driver for this bird-eating raptor species to settle in urban environments. However, as small passerine birds show particularly strong antipredator responses, sparrowhawks may not simply focus on patches of highest prey densities, but rather respond strategically to prey behavior, raising the importance of other parameters in determining the occurrence within urban landscapes.Methods: To deepen our knowledge on habitat requirements of urban sparrowhawks, bird surveys were carried out during winter between December 2005 and January 2017 in 36 city parks in Vienna, Austria. Besides food supply also park size, canopy heterogeneity and the connectivity with other green spaces were considered.Results: Occurrence of sparrowhawks was positively affected by increasing park size, prey density and the interaction between both. Bird feeder density and park connectivity with other green spaces were of minor importance in explaining the presence of this species. Canopy heterogeneity didn't affect city park occupancy by Eurasian Sparrowhawks.Conclusions: Our results suggest that large city parks, particularly when characterized by high prey densities, substantially contribute to protect and preserve ecologically important bird species such as raptors within the urban environment—a landscape already struggling with biodiversity losses and functional homogenization.
基金supported by Natural Science Foundation of China (No.11472225)
文摘In this paper, a method to design bird-strike-resistant aircraft structures is presented and illustrated through examples. The focus is on bird strike experiments and simulations. The explicit finite element software PAM-CRASH is employed to conduct bird strike simulations, and a coupled Smooth Particles Hydrodynamic（SPH） and Finite Element（FE） method is used to simulate the interaction between a bird and a target structure. The SPH method is explained, and an SPH bird model is established. Constitutive models for various structural materials, such as aluminum alloys, composite materials, honeycomb, and foam materials that are used in aircraft structures,are presented, and model parameters are identified by conducting various material tests. Good agreements between simulation results and experimental data suggest that the numerical model is capable of predicting the dynamic responses of various aircraft structures under a bird strike,and numerical simulation can be used as a tool to design bird-strike-resistant aircraft structures.
