Should I stay or should I fly? Migration phenology, individual-based migration decision and seasonal changes in foraging behaviour of Common Woodpigeons.

Migration is used by many species as a strategy to deal with a seasonally changing environment. For some species, migration patterns can vary across different or even within the same breeding area. The Common Woodpigeon Columba palumbus, an abundant and widespread Palearctic species, exhibits three migratory strategies (strictly migratory, partially migratory and resident) across its European breeding grounds. Based on ring recoveries and satellite tracking data, we investigated the migration and foraging behaviour of Woodpigeons breeding in Southwestern Europe (Portugal) and Central Europe (Germany). We found that individuals could be classified as residents (Portugal) or partial migrants (Germany), with migrating individuals following the European sector of the East Atlantic flyway, and mainly wintering in France. In addition to general data on migration phenology, we provide evidence for different migration strategies (migration of varying distances or resident behaviour), low wintering site fidelity and the use of multiple wintering sites. Furthermore, tracking data provided information on migratory behaviour in consecutive years, clearly showing that individuals may switch migratory strategies (resident vs. migrant) between years, i.e. are facultative partial migrants. While individuals from Portugal mainly stayed within a large park ('green urban area') year-round, Woodpigeons from the city of Giessen (Germany) regularly left the urban area to forage on surrounding farmland (with an average distance covered of 5.7 km), particularly from July to September. Overall, our results highlight the behavioural plasticity in Woodpigeons in terms of foraging and migration strategies within and amongst individuals as well as populations.

Global political responsibility for the conservation of albatrosses and large petrels.

Migratory marine species cross political borders and enter the high seas, where the lack of an effective global management framework for biodiversity leaves them vulnerable to threats. Here, we combine 10,108 tracks from 5775 individual birds at 87 sites with data on breeding population sizes to estimate the relative year-round importance of national jurisdictions and high seas areas for 39 species of albatrosses and large petrels. Populations from every country made extensive use of the high seas, indicating the stake each country has in the management of biodiversity in international waters. We quantified the links among national populations of these threatened seabirds and the regional fisheries management organizations (RFMOs) which regulate fishing in the high seas. This work makes explicit the relative responsibilities that each country and RFMO has for the management of shared biodiversity, providing invaluable information for the conservation and management of migratory species in the marine realm.

Prevalence and genetic diversity of avian haemosporidian parasites in wild bird species of the order Columbiformes.

Diseases can play a role in species decline. Among them, haemosporidian parasites, vector-transmitted protozoan parasites, are known to constitute a risk for different avian species. However, the magnitude of haemosporidian infection in wild columbiform birds, including strongly decreasing European turtle doves, is largely unknown. We examined the prevalence and diversity of haemosporidian parasites Plasmodium, Leucocytozoon and subgenera Haemoproteus and Parahaemoproteus in six species of the order Columbiformes during breeding season and migration by applying nested PCR, one-step multiplex PCR assay and microscopy. We detected infections in 109 of the 259 screened individuals (42%), including 15 distinct haemosporidian mitochondrial cytochrome b lineages, representing five H. (Haemoproteus), two H. (Parahaemoproteus), five Leucocytozoon and three Plasmodium lineages. Five of these lineages have never been described before. We discriminated between single and mixed infections and determined host species-specific prevalence for each parasite genus. Observed differences among sampled host species are discussed with reference to behavioural characteristics, including nesting and migration strategy. Our results support previous suggestions that migratory birds have a higher prevalence and diversity of blood parasites than resident or short-distance migratory species. A phylogenetic reconstruction provided evidence for H. (Haemoproteus) as well as H. (Parahaemoproteus) infections in columbiform birds. Based on microscopic examination, we quantified parasitemia, indicating the probability of negative effects on the host. This study provides a large-scale baseline description of haemosporidian infections of wild birds belonging to the order Columbiformes sampled in the northern hemisphere. The results enable the monitoring of future changes in parasite transmission areas, distribution and diversity associated with global change, posing a potential risk for declining avian species as the European turtle dove.

Weak effects of geolocators on small birds: A meta-analysis controlled for phylogeny and publication bias.

Currently, the deployment of tracking devices is one of the most frequently used approaches to study movement ecology of birds. Recent miniaturization of light-level geolocators enabled studying small bird species whose migratory patterns were widely unknown. However, geolocators may reduce vital rates in tagged birds and may bias obtained movement data. There is a need for a thorough assessment of the potential tag effects on small birds, as previous meta-analyses did not evaluate unpublished data and impact of multiple life-history traits, focused mainly on large species and the number of published studies tagging small birds has increased substantially. We quantitatively reviewed 549 records extracted from 74 published and 48 unpublished studies on over 7,800 tagged and 17,800 control individuals to examine the effects of geolocator tagging on small bird species (body mass <100 g). We calculated the effect of tagging on apparent survival, condition, phenology and breeding performance and identified the most important predictors of the magnitude of effect sizes. Even though the effects were not statistically significant in phylogenetically controlled models, we found a weak negative impact of geolocators on apparent survival. The negative effect on apparent survival was stronger with increasing relative load of the device and with geolocators attached using elastic harnesses. Moreover, tagging effects were stronger in smaller species. In conclusion, we found a weak effect on apparent survival of tagged birds and managed to pinpoint key aspects and drivers of tagging effects. We provide recommendations for establishing matched control group for proper effect size assessment in future studies and outline various aspects of tagging that need further investigation. Finally, our results encourage further use of geolocators on small bird species but the ethical aspects and scientific benefits should always be considered.

High prevalence of Trichomonas gallinae in wild columbids across western and southern Europe.

BACKGROUND: Avian trichomonosis is known as a widespread disease in columbids and passerines, and recent findings have highlighted the pathogenic character of some lineages found in wild birds. Trichomonosis can affect wild bird populations including endangered species, as has been shown for Mauritian pink pigeons Nesoenas mayeri in Mauritius and suggested for European turtle doves Streptopelia turtur in the UK. However, the disease trichomonosis is caused only by pathogenic lineages of the parasite Trichomonas gallinae. Therefore, understanding the prevalence and distribution of both potentially pathogenic and non-pathogenic T. gallinae lineages in turtle doves and other columbids across Europe is relevant to estimate the potential impact of the disease on a continental scale. RESULTS: We examined 281 samples from four wild columbid species for Trichomonas infection and determined the genetic lineages. The overall prevalence was 74%. There were significant differences between the species (P = 0.007). The highest prevalence was found in stock doves Columba oenas (86%, n = 79) followed by wood pigeons Columba palumbus (70%, n = 61) and turtle doves (67%, n = 65), while three of five collared doves Streptopelia decaocto (60%) were infected. We found seven different lineages, including four lineages present in columbids in the UK, one lineage already described from Spain and three new lineages, one of those found in a single turtle dove migrating through Italy and another one found in a breeding stock dove. Stock doves from Germany and collared doves from Malta were infected with a potentially pathogenic lineage (lineage A/B), which is known to cause lesions and mortality in columbids, raptors and finches. CONCLUSIONS: Generally, turtle doves showed high prevalence of Trichomonas infection. Furthermore, the potentially pathogenic lineage A/B (or genotype B according to previous literature) was found in a recovering stock dove population. Both findings are worrying for these columbid species due to the occasional epidemic character of trichomonosis, which can have severe negative effects on populations.

Seabird mortality induced by land-based artificial lights.

Artificial lights at night cause high mortality of seabirds, one of the most endangered groups of birds globally. Fledglings of burrow-nesting seabirds, and to a lesser extent adults, are attracted to and then grounded (i.e., forced to land) by lights when they fly at night. We reviewed the current state of knowledge of seabird attraction to light to identify information gaps and propose measures to address the problem. Although species in families such as Alcidae and Anatidae can be grounded by artificial light, the most affected seabirds are petrels and shearwaters (Procellariiformes). At least 56 species of Procellariiformes, more than one-third of them (24) threatened, are subject to grounding by lights. Seabirds grounded by lights have been found worldwide, mainly on oceanic islands but also at some continental locations. Petrel breeding grounds confined to formerly uninhabited islands are particularly at risk from light pollution due to tourism and urban sprawl. Where it is impractical to ban external lights, rescue programs of grounded birds offer the most immediate and employed mitigation to reduce the rate of light-induced mortality and save thousands of birds every year. These programs also provide useful information for seabird management. However, these data are typically fragmentary, biased, and uncertain and can lead to inaccurate impact estimates and poor understanding of the phenomenon of seabird attraction to lights. We believe the most urgently needed actions to mitigate and understand light-induced mortality of seabirds are estimation of mortality and effects on populations; determination of threshold light levels and safe distances from light sources; documentation of the fate of rescued birds; improvement of rescue campaigns, particularly in terms of increasing recovery rates and level of care; and research on seabird-friendly lights to reduce attraction.

Genomic evidence of demographic fluctuations and lack of genetic structure across flyways in a long distance migrant, the European turtle dove.

BACKGROUND: Understanding how past climatic oscillations have affected organismic evolution will help predict the impact that current climate change has on living organisms. The European turtle dove, Streptopelia turtur, is a warm-temperature adapted species and a long distance migrant that uses multiple flyways to move between Europe and Africa. Despite being abundant, it is categorized as vulnerable because of a long-term demographic decline. We studied the demographic history and population genetic structure of the European turtle dove using genomic data and mitochondrial DNA sequences from individuals sampled across Europe, and performing paleoclimatic niche modelling simulations. RESULTS: Overall our data suggest that this species is panmictic across Europe, and is not genetically structured across flyways. We found the genetic signatures of demographic fluctuations, inferring an effective population size (Ne) expansion that occurred between the late Pleistocene and early Holocene, followed by a decrease in the Ne that started between the mid Holocene and the present. Our niche modelling analyses suggest that the variations in the Ne are coincident with recent changes in the availability of suitable habitat. CONCLUSIONS: We argue that the European turtle dove is prone to undergo demographic fluctuations, a trait that makes it sensitive to anthropogenic impacts, especially when its numbers are decreasing. Also, considering the lack of genetic structure, we suggest all populations across Europe are equally relevant for conservation.

Morphometrics and stable isotopes differentiate wintering populations of a migratory bird.

BACKGROUND: Describing migratory connectivity in mobile animals is crucial for understanding the selective pressures acting on different populations throughout their life cycle. Tracking single individuals has provided valuable data, but for most species the data available are still spurious and usually limited to a few individuals. Since different populations of migratory birds can be distinguished by a combination of morphometric measurements and the isotopic composition of their feathers, it is possible to measure these parameters on a large sample to differentiate populations. METHODS: We studied northern wheatears, Oenanthe oenanthe, captured in their African wintering range and applied discriminant analyses on morphometric measurements and stable isotope signatures to determine whether birds found in different areas were distinguishable from each other. RESULTS: Morphometric and isotopic measurements alone were not sufficient to discriminate between the birds of ssp. oenanthe from different areas in Africa. When combining the two measurements, however, assignment to the different groups became substantially more accurate. Following the discriminant analysis of morphometrics and δ(2)H, δ(13)C, and δ(15)N isotopes signatures, 19 of 20 oenanthe from Kenya, 15 of 20 oenanthe from Mali/Mauritania, and 19 of 20 oenanthe from Niger were assigned correctly to their wintering area. CONCLUSIONS: Our results show that birds at different wintering sites can be distinguished from each other when using a combination of markers. We discuss the possible breeding origins of these wintering birds.

Keeping the clock set under the midnight sun: diurnal periodicity and synchrony of avian Isospora parasites cycle in the High Arctic.

For Isospora (Protozoa: Eimeriidae) parasites of passerine birds, diurnal periodicity of oocyst output is a well-described phenomenon. From the temporal zone to the tropics, oocyst production is correlated with the light-dark cycle, peaking in the afternoon hours. However, nothing is known about the existence of diurnal periodicity of these parasites in the birds of High Arctic environments, under permanent light during summer. We sampled free-ranging Snow Bunting (Aves: Passeriformes), on Svalbard in summer and tested oocysts output of Isospora plectrophenaxia. Here we show that under the permanent light conditions of Arctic summer in the wild, Isospora plectrophenaxia, a parasite of the Snow Bunting, still keeps the 24-h rhythm of oocyst output with the peak in the post-meridiem hours, despite the absence of diurnal periodicity in host's activity. Our findings prove the ability of avian Isospora to invoke alternative cues for synchronizing the circadian rhythms. Possible cues and adaptive significance of diurnal periodicity of parasite output in High Arctic are discussed. The maintenance of synchronization and timing of the parasite life-cycle stages is under positive selection pressure even in permanent daylight in the Arctic.

Fat stores in a migratory bird: a reservoir of carotenoid pigments for times of need?

Carotenoids are well known for their immune-stimulant function in birds and other vertebrates. Moreover, they have potential antioxidant capacity, scavenging free radicals and protecting cell compartments from oxidation. Most essential carotenoids are fat soluble and could be stored for times of need especially in adipose tissues, built up by migratory birds as the main source of energy on long-distance flights. In an exclusive diet experiment, garden warblers (Sylvia borin) were fed ad libitum with an experimental diet, enriched with two different dose rates of carotenoids, or with control food, during the period of their first autumn migration. Plasma carotenoid content was measured via HPLC and chroma of plasma and fat examined with a spectrophotometer. Birds were infected with Isospora spp. and intensity of infection determined by oocyst counts 3 days post infection. Plasma lutein levels and chroma of subcutaneous fat stores were positively correlated and chroma values of these fat stores increased in the birds that got the higher dose rate, whereas they decreased significantly in the control group after infection with Isospora spp. Chroma of subcutaneous fat deposits in vivo and intensity of Isospora infection were negatively correlated. By measuring the chroma of fat deposits in vivo, we show that fat can be a reservoir for carotenoids. These colorful antioxidants are stored in the fat and taken from there in times of a higher demand, e.g. when mounting an immune response to parasites.

Observations regarding the use of the aquaretic agent conivaptan for treatment of hyponatremia.

The treatment of hyponatremia, especially euvolemic and hypervolemic hyponatremia, has changed with the development of drugs which function as vasopressin receptor antagonists. These agents increase solute-free water excretion by the kidney resulting in an aquaresis. Conivaptan, a vasopressin receptor antagonist, has recently been approved by the FDA in the United States for use in the therapy of both euvolemic and hypervolemic hyponatremia. This report summarizes one center's experience with ten patients treated with this new drug. The patients had euvolemic hyponatremia with serum sodium levels less than 128 mEq/l. The same protocol was used in all patients with the conivaptan being given as a 20-mg intravenous loading dose followed by a 20-mg continuous 24-h infusion. Review of the data revealed that six of the ten patients had an excellent response to the therapy, with serum sodium increasing by a mean of 8.5+/-0.8 mEq/l (increases ranged from 7 to 12 mEq/l over 24 h). No significant changes in serum potassium levels or mean arterial pressures were noted. Two of the ten patients experienced a decrease in urine osmolality without a significant increase in serum sodium. Two other patients had only slight decreases in urine osmolality, and no significant increase in serum sodium levels. The data reveal that conivaptan is useful in the management of significant hyponatremia. There were no significant untoward effects, with the exception of one patient whose blood pressure decreased during the conivaptan infusion and who responded to cessation of the infusion and saline replacement therapy. This new class of drugs holds great promise for the treatment of dilutional hyponatremic disorders.