Search results for " Ornithology"
showing 10 items of 72 documents
Effects of geolocators on hatching success, return rates, breeding movements, and change in body mass in 16 species of Arctic-breeding shorebirds
2016
Background Geolocators are useful for tracking movements of long-distance migrants, but potential negative effects on birds have not been well studied. We tested for effects of geolocators (0.8–2.0 g total, representing 0.1–3.9 % of mean body mass) on 16 species of migratory shorebirds, including five species with 2–4 subspecies each for a total of 23 study taxa. Study species spanned a range of body sizes (26–1091 g) and eight genera, and were tagged at 23 breeding and eight nonbreeding sites. We compared breeding performance and return rates of birds with geolocators to control groups while controlling for potential confounding variables. Results We detected negative effects of tags for t…
A comparative study of Ural Owl Strix uralensis breeding season diet within its European breeding range, derived from nest box monitoring schemes
2018
Capsule: Voles are the main prey of the Ural Owl Strix uralensis in Europe, with larger prey and higher prey diversity being positively associated with owl breeding performance. Aims: To assess the breeding diet and its influence on the breeding performance of the Ural Owl across a north–south gradient of its European range using nest box monitoring data. Methods: Comparable monitoring of nest boxes in different biogeographical regions of Europe (Finland, Latvia, Slovenia) and diet analysis from nest samples to assess the taxonomic and trait influence of prey on owl breeding performance in different environments. Results: High plasticity in the Ural Owl hunting behaviour under different pre…
Differences in time and space use between two sympatric Acrocephalus warblers with similar diets
2016
Capsule: We found high diet overlap and different uses of space and time between Moustached Warblers Acrocephalus melanopogon and Reed Warblers Acrocephalus scirpaceus breeding in sympatry at a marshland in Spain. Aims: To study the degree of diet overlap between both species, their space use on a local scale and their breeding phenologies. Methods: We studied the breeding phenologies of the two species by standardized ringing activity. Spatial distribution was investigated by point counts. We determined diet composition from emetic samples and we collected invertebrates by standardized sweep-netting to estimate food availability. Results: Diet and prey selection were similar among species.…
Bayesian Immature Survival Analysis of the Largest Colony of Common Murre (Uria aalge) in the Baltic Sea
2019
In long-lived species, such as seabirds, immature survival is the most important life history parameter after adult survival. The assessment of immature survival has often been difficult due to extended periods in which young birds remain unobservable at sea. This study presents results on survival of immature Common Murre (Uria aalge) obtained from an extensive mark-recapture study of a large colony at Stora Karlso in the Baltic Sea, Sweden. This colony, in contrast with other colonies, has the unique feature that many 1-year-old birds return to the colony (12%). Between 2006 and 2016, 28,930 chicks were marked at fledging, of which 5,493 individuals were later resighted in the colony. Ann…
Dietary characterization of Savi s Warbler Locustaella luscinioides and Great Reed Warbler Acrocephalus rundinaceus in eastern Spain
2017
[EN] This research deals with two insectivorous reedbed-nesting songbirds, the Savi's Warbler Locustella luscinioides and the Great Reed Warbler Acrocephalus arundinaceus breeding at the Marjal de Pego-Oliva (Valencia-Alicante, Spain). Our aims were to study the diet and the prey selection of the two species and to assess the dietary differences between them. Diet composition has been assessed by examining samples off regurgitated food obtained using apomorphine as an emetic. Prey availability was estimated through standardized invertebrate sampling. The diet of the two warblers were significantly different and included arthropods belonging to the orders Araneida, Coleoptera, Hymenoptera, H…
Territoriality versus flocking in the Zenaida dove (Zenaida aurita): resource polymorphism revisited using morphological and genetic analyses.
2011
11 pages; International audience; The term “resource polymorphism” refers to the existence of alternative phenotypes in relation to resource use, as a result of disruptive selection. Evidence for resource polymorphism is widespread in fish but remains scarce in birds. Although Zenaida Doves (Zenaida aurita) usually defend year-round territories, doves on Barbados can also be observed foraging at seed-storage sites in large flocks with little, if any, inter-individual aggression. On the basis of morphological variation, it has been suggested (Sol et al. 2005) that this represents a case of resource polymorphism, primarily driven by competition for territories. Using new data, we revisited th…
Sexing birds using discriminant function analysis: a critical appraisal.
2011
9 pages; International audience; Discriminant function analysis (DFA) based on morphological measurements is a quick, inexpensive, and efficient method for sex determination in field studies on cryptically monomorphic bird species. However, behind the apparent standardization and relative simplicity of DFA lie subtle differences and pitfalls that have been neglected in some studies. Most of these concerns directly affect assessment of the discriminant performance, a parameter of crucial importance in practice because it provides a measure of the quality of an equation that may be used in later field studies. Using results from 141 published studies and simulations based on a large data set …
Changes in body mass and hormone levels between wintering and spring staging areas in Dark-bellied brent geese Branta bernicla bernicla
2006
International audience; Wintering migratory geese generally replenish protein stores lost during migration before building up their fat stores (Gauthier et al. 1992). Dark-bellied brent geese Branta bernicla bernicla winter mainly along the coasts of France, England and the south-western part of the Netherlands, and stage from March till late May mainly in the Wadden Sea, stretching from the northern Netherlands to Denmark (Ebbinge et al. 1999). During spring, geese accumulate body stores needed both for their long-distance migration to the breeding grounds and for reproduction (Spaans et al. 1993, Ebbinge and Spaans 1995). Dark-bellied brent geese, migrating about 5000 km between the winte…
Factors Shaping Breeding Phenology in Birds: An Assessment of Two Sympatric Acrocephalus Warblers with Different Life Histories
2020
El periodo reproductivo es un rasgo crucial de la historia de la vida e implica importantes consecuencias para la eficacia biologica. Las diferencias en las estrategias de historia de vida pueden conducir a diferentes respuestas a las mismas condiciones ambientales, incluso entre especies estrechamente relacionadas. Investigar los factores que afectan el periodo reproductivo en especies estrechamente relacionadas y simpatricas puede ayudar a comprender la relacion entre los diferentes rasgos de la historia de vida y las respuestas especificas de las especies a los factores ecologicos. En este trabajo investigamos los efectos del momento estacional (fotoperiodo), la variabilidad climatica lo…
Decomposition of nest material in tree holes and nest-boxes occupied by European Starlings Sturnus vulgaris: an experimental study
2017
Numerous bird species depend on the availability of tree cavities, and most non-excavators fill their cavities with considerable amounts of nest material. If not removed, this material can accumulate and render cavities unusable, as recorded in some nest-box studies. Data from earlier studies of tree cavities, however, showed that nest material can decrease mostly due to in situ decomposition, but the relative difference between nest decomposition in tree holes and nest-boxes is still unknown. We undertook parallel studies of decay in tree holes and nest-boxes used by European Starlings Sturnus vulgaris in oak-hornbeam stands (SW Poland). We inserted into its tree holes and nest-boxes litte…