Johannes Oehm, B. Thalinger, Hannes Mayr, M. Traugott
Avian carcasses can provide important information on the trophic ecology of birds. Usually, the number of carcasses available for examination is limited and therefore it is important to gain as much dietary information per specimen as possible. In piscivorous birds and raptors, the stomach has been the primary source of dietary information, whereas the gut (intestine) has so far been neglected as it usually contains only a few morphologically identifiable hard parts of prey. Molecular approaches have the potential to retrieve dietary information from the gut, although this has not yet been verified. As well as identifying the prey, it is important to estimate any secondary predation to avoid food web errors in dietary analyses. The assignment of accidentally consumed prey is notoriously difficult regardless of the prey identification approach used. In the present study, morphological and molecular analyses were, for the first time, combined to maximize the dietary information retrievable from the complete digestive tract of Great Cormorants Phalacrocorax carbo sinensis. Moreover, a novel approach based on predator–prey size ratios was applied to these piscivorous birds to minimize the number of samples that might contain secondarily predated prey. The stomach contents of the examined birds were found to provide the most dietary information when morphological and molecular analyses were used in combination. However, compared with the morphological approach, the molecular analysis increased the number of fish species detected by 39%. The molecular approach also permitted the identification of fish DNA in the Cormorant guts. Predator–prey size ratios derived from morphological analysis of fish hard parts can reduce the incidence of potential confounding influence of secondarily predated prey by 80%. Our findings demonstrate that a combination of morphological and molecular approaches maximizes the trophic information retrievable from bird carcasses.
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Pub Date : 1957-10-01DOI: 10.1111/j.1474-919X.1957.tb03050.x
F. Turček
Summary. 1. The species‐composition, number of individuals and biomass per one‐hectare are given. The three groups of areas studied were: (1) bare pastures, with an intermediate number of bird species, few individuals and high biomass of mainly carnivorous and insectivorous birds; (2) conifer plantations 1 to 5 years old, with the smallest number of bird species and the smallest biomass, but an intermediate number of individuals; (3) plantations six to twenty years old, with the highest number of both species and individuals of birds, but only intermediate biomass. 2. The change from pasture to forest occurs about six to ten years after planting. The last forest birds come in about 20 years after planting. 3. Birds have an important role in establishing the shrub layer and mixing some tree‐species into the plantation, by dissemination. 4. Throughout the entire successional series the bird population seems to have a kernel of species, while other species come or go and/or change in density with the stages.
{"title":"THE BIRD SUCCESSION IN THE CONIFER PLANTATIONS ON MAT‐GRASS LAND IN SLOVAKIA (CSR).","authors":"F. Turček","doi":"10.1111/j.1474-919X.1957.tb03050.x","DOIUrl":"https://doi.org/10.1111/j.1474-919X.1957.tb03050.x","url":null,"abstract":"Summary. 1. The species‐composition, number of individuals and biomass per one‐hectare are given. The three groups of areas studied were: (1) bare pastures, with an intermediate number of bird species, few individuals and high biomass of mainly carnivorous and insectivorous birds; (2) conifer plantations 1 to 5 years old, with the smallest number of bird species and the smallest biomass, but an intermediate number of individuals; (3) plantations six to twenty years old, with the highest number of both species and individuals of birds, but only intermediate biomass. 2. The change from pasture to forest occurs about six to ten years after planting. The last forest birds come in about 20 years after planting. 3. Birds have an important role in establishing the shrub layer and mixing some tree‐species into the plantation, by dissemination. 4. Throughout the entire successional series the bird population seems to have a kernel of species, while other species come or go and/or change in density with the stages.","PeriodicalId":290967,"journal":{"name":"The Ibis","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1957-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121588416","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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