After breeding,Black-necked Grebes(Podiceps nigricollis)perform a moult-migration to autumn hypersaline staging sites,where they moult the flight feathers and forage on superabundant brine shrimp(Artemia spp.)before l...After breeding,Black-necked Grebes(Podiceps nigricollis)perform a moult-migration to autumn hypersaline staging sites,where they moult the flight feathers and forage on superabundant brine shrimp(Artemia spp.)before leaving for wintering areas.During the stay in moulting sites,the grebes experience changes in organs and muscle size(atrophy,hypertrophy),and almost double their body mass,which has been suggested to act as an insurance against a collapse in prey availability in late autumn.During two years we collected blood samples from hundreds of individuals at one of the most important European moulting sites(the Odiel marshes,SW Spain),which is a highly polluted area due to mining drainage and chemical industry.We assessed the potential effect of moulting stage,day of the year and body condition on 16 blood biochemical parameters.Because of the changes in prey availability and body composition of grebes,we expected some physiological adjustments during moult.Elevated levels of cholesterol suggested that birds in active moult increased foraging effort to face the costs of moulting.There was increased amount of lactate dehydrogenase,corresponding to periods of breast muscle atrophy.Birds in active moult augmented protein ingestion,likely to account for the requirements of feather growth.We also show that the probability of fasting due to low prey availability increased late in the moulting season,as demonstrated by an increase in plasmaβ-hydroxy-butyrate.展开更多
Brine shrimp Artemia franciscana provide food for many migrating and staging birds that spend summer and fall on Great Salt Lake,Utah,USA.Artemia produce live young and cysts(hard-walled eggs);these cysts are commerci...Brine shrimp Artemia franciscana provide food for many migrating and staging birds that spend summer and fall on Great Salt Lake,Utah,USA.Artemia produce live young and cysts(hard-walled eggs);these cysts are commercially harvested on Great Salt Lake and support a large industry in Utah.It is unclear the impact that millions of hungry birds have on the Artemia population in the lake.To help assess that,this study evaluated cyst viability(percentage of cysts that contain an embryo)and hatchability(percent of cysts that hatch)from cysts that had passed through the digestive tract of eared grebes Podiceps nigricollis and cysts obtained directly from Great Salt Lake at the same site where each grebe was collected.Hatchability was significantly higher for cysts collected from the water column(19%)than from the stomach(0.3%)or intestines(3%)of eared grebes.Viability also was significantly different for cysts collected from the water column(29%),stomach(0.7%),and intestines(5%).These results indicate that eared grebes nutritionally benefit from eating cysts and that they may be an important food source for grebes in late fall after the adult population of Artemia dies off due to the water becoming too cold.Also,enough cysts survive their passage through the digestive system that grebes can vector hatchable cysts to other waterbodies.展开更多
基金P07-CVI-02700 from the Con-sejería de Innovacion,Ciencia y Empresa(Junta de Andalucía)/EU-ERDF.
文摘After breeding,Black-necked Grebes(Podiceps nigricollis)perform a moult-migration to autumn hypersaline staging sites,where they moult the flight feathers and forage on superabundant brine shrimp(Artemia spp.)before leaving for wintering areas.During the stay in moulting sites,the grebes experience changes in organs and muscle size(atrophy,hypertrophy),and almost double their body mass,which has been suggested to act as an insurance against a collapse in prey availability in late autumn.During two years we collected blood samples from hundreds of individuals at one of the most important European moulting sites(the Odiel marshes,SW Spain),which is a highly polluted area due to mining drainage and chemical industry.We assessed the potential effect of moulting stage,day of the year and body condition on 16 blood biochemical parameters.Because of the changes in prey availability and body composition of grebes,we expected some physiological adjustments during moult.Elevated levels of cholesterol suggested that birds in active moult increased foraging effort to face the costs of moulting.There was increased amount of lactate dehydrogenase,corresponding to periods of breast muscle atrophy.Birds in active moult augmented protein ingestion,likely to account for the requirements of feather growth.We also show that the probability of fasting due to low prey availability increased late in the moulting season,as demonstrated by an increase in plasmaβ-hydroxy-butyrate.
基金Supported by the Great Salt Lake Ecosystem Program of Utah Division of Wildlife Resources,Utah Agricultural Experiment Station(article No.9534)and Ecology Center of Utah State Universityapproved by Institutional Animal Care and Use Committee of Utah State University(10087)+2 种基金permitted by the state of Utah(1BAND10069,2COLL10039)the U.S.Bird Banding Lab(21175)and the U.S.Fish and Wildlife Service(MB693916-0).
文摘Brine shrimp Artemia franciscana provide food for many migrating and staging birds that spend summer and fall on Great Salt Lake,Utah,USA.Artemia produce live young and cysts(hard-walled eggs);these cysts are commercially harvested on Great Salt Lake and support a large industry in Utah.It is unclear the impact that millions of hungry birds have on the Artemia population in the lake.To help assess that,this study evaluated cyst viability(percentage of cysts that contain an embryo)and hatchability(percent of cysts that hatch)from cysts that had passed through the digestive tract of eared grebes Podiceps nigricollis and cysts obtained directly from Great Salt Lake at the same site where each grebe was collected.Hatchability was significantly higher for cysts collected from the water column(19%)than from the stomach(0.3%)or intestines(3%)of eared grebes.Viability also was significantly different for cysts collected from the water column(29%),stomach(0.7%),and intestines(5%).These results indicate that eared grebes nutritionally benefit from eating cysts and that they may be an important food source for grebes in late fall after the adult population of Artemia dies off due to the water becoming too cold.Also,enough cysts survive their passage through the digestive system that grebes can vector hatchable cysts to other waterbodies.
