A small,isolated Amur tiger population ranges across the southwest Primorskii Krai region in Russia and Hunchun region in China.Many individuals,with“dual nationality,”cross the border frequently.Formulating effecti...A small,isolated Amur tiger population ranges across the southwest Primorskii Krai region in Russia and Hunchun region in China.Many individuals,with“dual nationality,”cross the border frequently.Formulating effective conservation strategies requires a clear understanding of tiger food requirements in both countries.While the diets of tigers ranging in Russia is clearly understood,little is known of the tigers’feeding habits in China..We used scat analysis combined with data on the abundance of 4 prey species to examine Amur tiger diet and prey preferences in Hunchun.We examined 53 tiger scat samples from 2011 to 2016 and found that tigers preyed on 12 species(11 species in winter),4 of which were domestic animals with 33.58%biomass contribution;this was the first record of Amur tigers eating lynx in this area.Tigers showed a strong preference for wild boar(Jacobs index:+0.849),which were also the most frequently consumed prey,and a strong avoidance of roe deer(Jacobs index:–0.693).On the Russian side,domestic animals(just dog)were rarely found in tiger scat,and tigers did not show strong avoidance of roe deer,but of sika deer.We also found red deer footprints during winter surveys and that tigers ate red deer on the Chinese side,while there was no record of red deer feeding on the Russian side.Reducing or eliminating human disturbance,such as grazing,is essential to recovering tiger prey and habitat in this area and the Sino–Russian joint ungulate annual survey is indispensable for prey estimates of this small,isolated Amur tiger population.展开更多
Prey have evolved anti-predator defences that reduce or eliminate the risk of predation. Predators often reproduce at specific sites over many years causing permanent threats to local prey species. Such prey may respo...Prey have evolved anti-predator defences that reduce or eliminate the risk of predation. Predators often reproduce at specific sites over many years causing permanent threats to local prey species. Such prey may respond by moving elsewhere thereby reducing local population abundance, or they may stay put and adjust their behavior to the presence of predators. We tested these predictions by analyzing population abundance and anti-predator behavior within 100 m of and 500 m away from nests of sparrowhawks Accipiter nisus and goshawks A. gentilis for 80 species of birds. Population abundance of prey was reduced by 11% near goshawk nests and by 15% near sparrowhawk nests when compared with nearby control sites in similar habitats. Flight initiation distance （FID） of prey, estimated as the distance at which birds took flight when approached by a human, increased by 50% in the presence of hawk nests, providing evidence of adjustment of anti-predator behavior to prevailing risks of predation. Susceptibility to predation was estimated as log transformed abundance of the observed number of prey items obtained from prey remains collected around nests minus log transformed expected number of prey according to point counts of breeding birds. FID increased from 10 to 46 m with increasing susceptibility of prey species to predation by the goshawk and from 12 to 15 m with increasing susceptibility of prey species to predation by the sparrowhawk. These findings suggest that prey adjust their distribution and anti-predator behavior to the risk of predation.展开更多
Generalist mammalian predators hunt for prey in different ways than raptors,often relying on ambush attack.Such differences in predator behavior can have profound effects on susceptibility of different species of prey...Generalist mammalian predators hunt for prey in different ways than raptors,often relying on ambush attack.Such differences in predator behavior can have profound effects on susceptibility of different species of prey to predation,but can also modify the behavior of prey.We investigated susceptibility of common birds to predation by domestic cats Felis catus,relying on an extensive data set on prey abundance and prey availability as determined by standardized bird counts.Susceptibility to cat predation for different species of birds was not significantly correlated with susceptibility to predation by sparrowhawk Accipiter nisus,but with susceptibility to goshawk Accipiter gentilis predation. Susceptibility to goshawk predation was independently predicted by susceptibility to cat and sparrowhawk predation.We cross-validated our estimate of susceptibilityto cat predation by showing that the frequency of birds with tail loss increased strongly with sus-ceptibility to cat predation.Male birds were disproportionately preyed upon,especially if havingsong posts low in the vegetation,and if having short flight distances when singing.Colonially breeding species were less susceptible to predation than solitary species.Bird species with high levels of innate immune defense against bacterial infections had high susceptibility to cat predation.These findings suggest that predation by cats has been an important selection pressure affecting anti-predation behavior,sexual display and immune function in common birds.展开更多
The poinsettia thrips Echinothrips americanus Morgan is a relatively new pest that has spread rapidly worldwide and causes serious damage in both vegetable and ornamental plants.In this study,we investigated if and ho...The poinsettia thrips Echinothrips americanus Morgan is a relatively new pest that has spread rapidly worldwide and causes serious damage in both vegetable and ornamental plants.In this study,we investigated if and how effective this pest can be controlled in gerbera by the omnivorous predator Macrolophus pygmaeus(Rambur).Because herbivores on plants can interact through a shared predator,we also investigated how poinsettia thrips control is affected by the presence of the greenhouse whitefly Trialeurodes vaporariorum(Westwood),a pest that commonly coexists with E.americanus in gerbera.In laboratory studies,we found that the predator M.pygmaeus fed on both pests when offered together.Olfactometer tests showed a clear preference of the predators for plants infested by whiteflies but not by thrips.In a greenhouse experiment,densities of both pests on single gerbera plants were reduced to very low levels by the predator,either with both pests present together or alone.Hence,predator‐mediated effects between whiteflies and thrips played only a minor role.The plant feeding of the shared predator probably reduced the dependence of predator survival and reproduction on the densities of the two pests,thereby weakening potential predator‐mediated effects.Thus,M.pygmaeus is a good candidate for biological control of both pests in gerbera.However,further research is needed to investigate pest control at larger scales,when the pests can occur on different plants.展开更多
基金This study was funded by the National Key Programme of Research and Development,Ministry of Science and Technology(2016YFC0503200)the Fundamental Research Funds for the Central Universities(2572014EA06,2572016AA10)+2 种基金the National Natural Science Foundation of China(Grant ID 31272336,31572285)China Postdoctoral Science Foundation funded project(2015M581416,LBH-Z14017)2 projects of the State Forestry Administration,entitled“Study on Tiger and Amur Leopard Population Resources Monitoring Technology”and“Survey Standard Compiling and Information Summary of Amur Leopard and Tiger Population and Habitat.”。
文摘A small,isolated Amur tiger population ranges across the southwest Primorskii Krai region in Russia and Hunchun region in China.Many individuals,with“dual nationality,”cross the border frequently.Formulating effective conservation strategies requires a clear understanding of tiger food requirements in both countries.While the diets of tigers ranging in Russia is clearly understood,little is known of the tigers’feeding habits in China..We used scat analysis combined with data on the abundance of 4 prey species to examine Amur tiger diet and prey preferences in Hunchun.We examined 53 tiger scat samples from 2011 to 2016 and found that tigers preyed on 12 species(11 species in winter),4 of which were domestic animals with 33.58%biomass contribution;this was the first record of Amur tigers eating lynx in this area.Tigers showed a strong preference for wild boar(Jacobs index:+0.849),which were also the most frequently consumed prey,and a strong avoidance of roe deer(Jacobs index:–0.693).On the Russian side,domestic animals(just dog)were rarely found in tiger scat,and tigers did not show strong avoidance of roe deer,but of sika deer.We also found red deer footprints during winter surveys and that tigers ate red deer on the Chinese side,while there was no record of red deer feeding on the Russian side.Reducing or eliminating human disturbance,such as grazing,is essential to recovering tiger prey and habitat in this area and the Sino–Russian joint ungulate annual survey is indispensable for prey estimates of this small,isolated Amur tiger population.
文摘Prey have evolved anti-predator defences that reduce or eliminate the risk of predation. Predators often reproduce at specific sites over many years causing permanent threats to local prey species. Such prey may respond by moving elsewhere thereby reducing local population abundance, or they may stay put and adjust their behavior to the presence of predators. We tested these predictions by analyzing population abundance and anti-predator behavior within 100 m of and 500 m away from nests of sparrowhawks Accipiter nisus and goshawks A. gentilis for 80 species of birds. Population abundance of prey was reduced by 11% near goshawk nests and by 15% near sparrowhawk nests when compared with nearby control sites in similar habitats. Flight initiation distance （FID） of prey, estimated as the distance at which birds took flight when approached by a human, increased by 50% in the presence of hawk nests, providing evidence of adjustment of anti-predator behavior to prevailing risks of predation. Susceptibility to predation was estimated as log transformed abundance of the observed number of prey items obtained from prey remains collected around nests minus log transformed expected number of prey according to point counts of breeding birds. FID increased from 10 to 46 m with increasing susceptibility of prey species to predation by the goshawk and from 12 to 15 m with increasing susceptibility of prey species to predation by the sparrowhawk. These findings suggest that prey adjust their distribution and anti-predator behavior to the risk of predation.
文摘Generalist mammalian predators hunt for prey in different ways than raptors,often relying on ambush attack.Such differences in predator behavior can have profound effects on susceptibility of different species of prey to predation,but can also modify the behavior of prey.We investigated susceptibility of common birds to predation by domestic cats Felis catus,relying on an extensive data set on prey abundance and prey availability as determined by standardized bird counts.Susceptibility to cat predation for different species of birds was not significantly correlated with susceptibility to predation by sparrowhawk Accipiter nisus,but with susceptibility to goshawk Accipiter gentilis predation. Susceptibility to goshawk predation was independently predicted by susceptibility to cat and sparrowhawk predation.We cross-validated our estimate of susceptibilityto cat predation by showing that the frequency of birds with tail loss increased strongly with sus-ceptibility to cat predation.Male birds were disproportionately preyed upon,especially if havingsong posts low in the vegetation,and if having short flight distances when singing.Colonially breeding species were less susceptible to predation than solitary species.Bird species with high levels of innate immune defense against bacterial infections had high susceptibility to cat predation.These findings suggest that predation by cats has been an important selection pressure affecting anti-predation behavior,sexual display and immune function in common birds.
基金This study was funded by the Dutch Product Board for Horticulture.Part of this work was supported by COST Action FA 1105:Towards a sustainable and productive EU organic greenhouse horticulture.
文摘The poinsettia thrips Echinothrips americanus Morgan is a relatively new pest that has spread rapidly worldwide and causes serious damage in both vegetable and ornamental plants.In this study,we investigated if and how effective this pest can be controlled in gerbera by the omnivorous predator Macrolophus pygmaeus(Rambur).Because herbivores on plants can interact through a shared predator,we also investigated how poinsettia thrips control is affected by the presence of the greenhouse whitefly Trialeurodes vaporariorum(Westwood),a pest that commonly coexists with E.americanus in gerbera.In laboratory studies,we found that the predator M.pygmaeus fed on both pests when offered together.Olfactometer tests showed a clear preference of the predators for plants infested by whiteflies but not by thrips.In a greenhouse experiment,densities of both pests on single gerbera plants were reduced to very low levels by the predator,either with both pests present together or alone.Hence,predator‐mediated effects between whiteflies and thrips played only a minor role.The plant feeding of the shared predator probably reduced the dependence of predator survival and reproduction on the densities of the two pests,thereby weakening potential predator‐mediated effects.Thus,M.pygmaeus is a good candidate for biological control of both pests in gerbera.However,further research is needed to investigate pest control at larger scales,when the pests can occur on different plants.
