Hae
Aineistot 1-10 / 20
Maternally transferred thyroid hormones and life-history variation in birds
<p>1. In vertebrates, thyroid hormones (THs) play an important role in the regulation of growth, development, metabolism, photoperiodic responses and migration. Maternally transferred THs are important for normal early ...
Habitat use by post-fledging white-tailed eagles shows avoidance of human infrastructure and agricultural areas
Habitat use studies provide invaluable information for the conservation of species that suffer from habitat loss or degradation. We used satellite telemetry to study the habitat use of white-tailed eagles (Haliaeetus ...
A rapid increase of large-sized waterfowl does not explain the population declines of small-sized waterbird at their breeding sites
Certain species experience rapid population increases in human-modified and -affected environments. Conservation actions and increased wintertime food availability have led to a population increase of several large herbivorous ...
Birds of three worlds: moult migration to high Arctic expands a boreal-temperate flyway to a third biome
<p>Background: Knowledge on migration patterns and flyways is a key for understanding the dynamics of migratory populations and evolution of migratory behaviour. Bird migration is usually considered to be movements between ...
Identifying the paths of climate effects on population dynamics: dynamic and multilevel structural equation model around the annual cycle
<p>How environmental factors influence population dynamics in long-distance migrants is complicated by the spatiotemporal diversity of the environment the individuals experience during the annual cycle. The effects of weather on several different aspects of life history have been well studied, but a better understanding is needed on how weather affects population dynamics through the different associated traits. We utilise 77 years of data from pied flycatcher (Ficedula hypoleuca), to identify the most relevant climate signals associated with population growth rate. The strongest signals on population growth were observed from climate during periods when the birds were not present in the focal location. The population decline was associated with increasing precipitation in the African non-breeding quarters in the autumn (near the arrival of migrants) and with increasing winter temperature along the migration route (before migration). The number of fledglings was associated positively with increasing winter temperature in non-breeding area and negatively with increasing winter temperature in Europe. These possible carry-over effects did not arise via timing of breeding or clutch size but the exact mechanism remains to be revealed in future studies. High population density and low fledgling production were the intrinsic factors reducing the breeding population. We conclude that weather during all seasons has the potential to affect the reproductive success or population growth rate of this species. Our results show how weather can influence the population dynamics of a migratory species through multiple pathways, even at times of the annual cycle when the birds are in a different location than the climate signal.</p>...
Within-individual repeatability in telomere length: A meta-analysis in nonmammalian vertebrates
Telomere length is increasingly used as a biomarker of long-term somatic state and future survival prospects. While most studies have overlooked this aspect, biological interpretations based on a given telomere length will ...
Interplays between pre- and post-natal environments affect early-life mortality, body mass and telomere dynamics in the wild
<p>Early-life conditions are crucial determinants of phenotype and fitness. The effects of pre- and post-natal conditions on fitness prospects have been widely studied but their interactive effects have received less attention. In birds, asynchronous hatching creates challenging developmental conditions for the last-hatched chicks, but differential allocation in last-laid eggs might help to compensate this initial handicap. The relative importance and potential interaction between pre- and post-hatching developmental conditions for different fitness components remains mostly unknown. We manipulated hatching order in wild pied flycatchers (Ficedula hypoleuca), creating three groups: natural asynchrony (last-laid eggs hatching last), reversed asynchrony (last-laid eggs hatching first) and hatching synchrony (all eggs hatching at once). We examined the effects of these manipulations on early-life survival, growth and telomere length, a potential cellular biomarker of fitness prospects. Mortality was mostly affected by hatching order, with last-hatched chicks being more likely to die. Early-life telomere dynamics and growth were influenced by the interplays between laying and hatching order. Last-laid but first-hatched chicks were heavier but had shorter telomeres 5 days after hatching than their siblings, indicating rapid early growth with potential adverse consequences on telomere length. Synchronous chicks did not suffer any apparent cost of hatching synchronously. Impaired phenotypes only occurred when reversing the natural hatching order (i.e. developmental mismatch), suggesting that maternal investment in last-laid eggs might indeed counterbalance the initial handicap of last-hatched chicks. Our experimental study thus highlights that potential interplays between pre- and post-natal environments are likely to shape fitness prospects in the wild.</p>...
The Indo-European flyway: Opportunities and constraints reflected by Common Rosefinches breeding across Europe
<p>Aim </p><p>The configuration of the earth's landmasses influences global weather systems and spatiotemporal resource availability, thereby shaping biogeographical patterns and migratory routes of animals. Here, we aim to identify potential migratory barriers and corridors, as well as general migration strategies within the understudied Indo-European flyway.<br></p><p>Location <br></p><p>Europe, Central Asia.<br></p><p>Major taxon studied <br></p><p>Common rosefinches.<br></p><p>Methods <br></p><p>We used a combination of theoretical optimization modelling and empirical tracking of Common Rosefinches (Carpodacus erythrinus) breeding across a large latitudinal gradient in Europe. First, we identified optimal migration routes driven by wind and resource availability along the Indo-European flyway. Second, we tracked rosefinches from five breeding populations using light-level geolocators. Finally, we compared to what extent empirical tracks overlapped with the modelled optimal routes.<br></p><p>Results<br></p><p>In autumn, theoretical wind driven migration routes formed a broad-front corridor connecting Europe and the Indian Subcontinent while the theoretical resource driven routes formed a distinct north-south divide. The latter pattern also reflected the rosefinch tracks with all but the most southerly breeding birds making a northern detour towards non-breeding sites in Pakistan and India. In spring, the resource availability model predicted a similar migratory divide, however, the southern route seemed relatively more favourable and closely matched with the optimal wind driven migration routes. Spring tracking data showed larger overlap with the modelled wind driven migration routes compared to the resource driven routes.<br></p><p>Main conclusions<br></p><p>Optimal wind and resource driven migration routes along the Indo-European flyway are seasonally specific and to a large extend do not overlap with one another. Under these conditions, migratory birds adopt seasonally distinct migration strategies following energy minimization strategy in autumn, driven by resource availability, and time minimizing strategy in spring, driven by wind conditions. Our optimal migration models can be applied worldwide and used to validate against empirical data to explain large-scale biogeographic pattern of migratory animals.</p>...
Predicting spatio-temporal distributions of migratory populations using Gaussian process modelling
<p><br></p><p>1. Knowledge concerning spatio-temporal distributions of populations is a prerequisite for successful conservation and management of migratory animals. Achieving cost-effective monitoring of large-scale ...