Egg rejection in birds is a specific adaptation toward avian brood parasitism,whereas nest sanitation is a general behavior for cleaning the nest and avoiding predation.However,both behaviors refer to the action of ej...Egg rejection in birds is a specific adaptation toward avian brood parasitism,whereas nest sanitation is a general behavior for cleaning the nest and avoiding predation.However,both behaviors refer to the action of ejecting objects out of the nest,and nest sanitation has been proposed as a preadaptation for egg rejection.Here,we tested the eliciting effect of nest sanitation on egg rejection in the red-whiskered bulbul Pycnonotus jocosus,a potential host species that are sympatric with parasitic cuckoos.We conducted meta-analyses of previous studies on both nest sanitation and egg rejection,in order to evaluate the consistency of our conclusions.Our results showed that nest sanitation did not elicit egg rejection in P.jocosus.The conclusions concerning such an eliciting effect from previous studies were mixed,whereas the methodologies were inconsistent,making the studies unsuitable for comparisons.However,the ejection frequency of nest sanitation was consistently higher than the frequency of egg rejection across different host species or populations.These results suggest that nest sanitation,which is an ancient behavior,is more fundamental than egg rejection,but the effect of the former on the latter is complex and needs further study.Standardized methodologies and the integration of behavior,physiology,and modeling may provide better opportunities to explore the relationship between nest sanitation and egg rejection.展开更多
Many invasive species exploit anthropogenically disturbed habitats, but most of those taxa evolved long before humans. Presumably, then, an ability to use natural （non-anthropogenic） disturbances pre-adapted invader...Many invasive species exploit anthropogenically disturbed habitats, but most of those taxa evolved long before humans. Presumably, then, an ability to use natural （non-anthropogenic） disturbances pre-adapted invaders to a world later degraded by people. Studies on invasive species in naturally disturbed habitats thus can clarify the ancestral niche of invaders. In the Australian tropics, metallic starlings Aplonis metallica nest communally in emergent rainforest trees during the wet-season, and invasive cane toads Rhinella marina join other predators （mammals, birds, reptiles, and other anurans） to exploit the food resources beneath those trees. Compared to conspecifics found along nearby roads through the forest, cane toads beneath bird-nesting trees occur at higher densities, and are smaller in body size. The sex ratio is female-biased, and recapture records suggest that fe- males may be philopatric at these sites （whereas recaptures were rare for both sexes found along the roads）. Some toads were found under the same trees in successive wet-seasons. Spooling showed that distances moved per night were similar along the road versus under the trees, but toads under trees showed lower net displacements. Diets also differed （based upon scat analysis）, with tree toads feeding more on beetles and less on ants. These nutrient-rich hotspots are ex- ploited primarily by adult females and juvenile toads, whereas adult males congregate at breeding sites. By magnifying pre-existing intraspecific divergences in habitat use, bird rookeries may en- hance population viability of cane toads by enabling critical age and sex classes to exploit food- rich patches that are rarely used by adult males.展开更多
基金This work was funded by the Hainan Provincial Natural Science Foundation of China(320CXTD437 and 2019RC189 to C.Y.)the National Science Foundation of China(No.31672303 to C.Y.).
文摘Egg rejection in birds is a specific adaptation toward avian brood parasitism,whereas nest sanitation is a general behavior for cleaning the nest and avoiding predation.However,both behaviors refer to the action of ejecting objects out of the nest,and nest sanitation has been proposed as a preadaptation for egg rejection.Here,we tested the eliciting effect of nest sanitation on egg rejection in the red-whiskered bulbul Pycnonotus jocosus,a potential host species that are sympatric with parasitic cuckoos.We conducted meta-analyses of previous studies on both nest sanitation and egg rejection,in order to evaluate the consistency of our conclusions.Our results showed that nest sanitation did not elicit egg rejection in P.jocosus.The conclusions concerning such an eliciting effect from previous studies were mixed,whereas the methodologies were inconsistent,making the studies unsuitable for comparisons.However,the ejection frequency of nest sanitation was consistently higher than the frequency of egg rejection across different host species or populations.These results suggest that nest sanitation,which is an ancient behavior,is more fundamental than egg rejection,but the effect of the former on the latter is complex and needs further study.Standardized methodologies and the integration of behavior,physiology,and modeling may provide better opportunities to explore the relationship between nest sanitation and egg rejection.
文摘Many invasive species exploit anthropogenically disturbed habitats, but most of those taxa evolved long before humans. Presumably, then, an ability to use natural （non-anthropogenic） disturbances pre-adapted invaders to a world later degraded by people. Studies on invasive species in naturally disturbed habitats thus can clarify the ancestral niche of invaders. In the Australian tropics, metallic starlings Aplonis metallica nest communally in emergent rainforest trees during the wet-season, and invasive cane toads Rhinella marina join other predators （mammals, birds, reptiles, and other anurans） to exploit the food resources beneath those trees. Compared to conspecifics found along nearby roads through the forest, cane toads beneath bird-nesting trees occur at higher densities, and are smaller in body size. The sex ratio is female-biased, and recapture records suggest that fe- males may be philopatric at these sites （whereas recaptures were rare for both sexes found along the roads）. Some toads were found under the same trees in successive wet-seasons. Spooling showed that distances moved per night were similar along the road versus under the trees, but toads under trees showed lower net displacements. Diets also differed （based upon scat analysis）, with tree toads feeding more on beetles and less on ants. These nutrient-rich hotspots are ex- ploited primarily by adult females and juvenile toads, whereas adult males congregate at breeding sites. By magnifying pre-existing intraspecific divergences in habitat use, bird rookeries may en- hance population viability of cane toads by enabling critical age and sex classes to exploit food- rich patches that are rarely used by adult males.
