Biological Earth observation with animal sensors

Space-based tracking technology using low-cost miniature tags is now delivering data on fine-scale animal movement at near-global scale. Linked with remotely sensed environmental data, this offers a biological lens on habitat integrity and connectivity for conservation and human health; a global network of animal sentinels of environmen-tal change

Migratory Species Show Distinct Patterns in Corticosterone Levels during Spring and Autumn Migrations

Twice a year billions of birds migrate between breeding and wintering grounds. To facilitate migrations, birds develop migratory disposition, a complex suite of behavioral and physiological adjustments. Glucocorticoid hormone corticosterone is involved in the regulation of migratory behavior and physiology, however no consensus on its exact role in controlling avian migration exists. Using a large dataset on seven songbird species (long- and short-distance migrants) obtained during eleven consecutive migratory seasons on the Courish Spit of the Baltic Sea, we showed the general tendency of similar baseline corticosterone concentrations during both migrations, although stress-induced levels were generally much higher during spring. No difference between long- and short-distance migrants was found in either baseline or stress-induced levels, while there was substantial between-species variation, especially in baseline concentrations. The distinct patterns of corticosterone secretion during seasonal migrations even in ecologically similar species indicate that it is likely to be a species-specific trait. Thus, our study corroborates the inconsistency found in earlier studies and demonstrates how scientific understanding of the role of corticosterone during migration is still evolving. Rather low baseline corticosterone concentrations observed in this study emphasize that birds in both migratory seasons were not in a “stressed” state before capture

FDR and food intake

FDR of temporarily caged and wild wheatears on Helgond island, Germany

Data from: Faster spring migration in northern wheatears is not explained by an endogenous seasonal difference in refueling rates

A widespread phenomenon in migrant birds is that they travel faster in spring than in autumn. During migration birds spend most time at stopover sites and, correspondingly, the faster spring migration is mainly explained by shorter stopovers in spring than autumn. Because a main purpose of stopovers is to replenish the fuel used in flight, a higher rate of fuel deposition (FDR) in spring is thought to explain the shorter stopovers and hence shorter total duration of migration in spring. Critical migratory processes, including the onset and extent of pre-migratory fueling, are endogenously regulated. It is therefore not unlikely that refueling at stopover sites is, at least partly, also under endogenous control. We here tested whether there is an endogenous seasonal difference in food intake and FDR, which could contribute to shorter stopovers and hence faster migration in spring. We measured daily food intake and daily FDR in two subspecies of the northern wheatear Oenanthe oenanthe, temporarily confined at stopover under identical constant indoor conditions in spring and autumn. The two wheatear subspecies differed markedly in absolute food intake and FDR. Within subspecies, however, food intake and FDR did not differ between spring and autumn, indicating that faster spring migration in northern wheatears is not explained by an endogenously controlled seasonal difference in birds’ motivation to refuel. To further substantiate this claim, similar measurements should be taken at other locations along northern wheatears’ migration routes. Comparable experiments in other species could test the generality of our results

Data_Demina_etal_2018

This Zip archive includes one csv- and one txt -file. These files provide all data used for the analyses included in the research article along with short description of columns in the data table

Juvenile dispersal in Reed Warblers Acrocephalus scirpaceus at night

The aim of this study was to test whether juvenile dispersal in Reed Warblers Acrocephalus scirpaceus takes place at night. If this does occur then the questions arise: “in which part of the night, at what age and physiological condition do they disperse?” In 1999 on the Courish Spit on the Baltic we ringed large numbers of Reed Warbler pulli at three isolated reedbed sites. Each night from late July until mid September we tape-lured Reed Warblers in a habitat atypical of this species. The trapping site was nearly equidistant from the two main plots where pulli were ringed. Additionally, in 1997-1999 at one of the reedbed study sites Reed Warblers starting and ending nocturnal flights were captured in high nets while at the same site, during the daytime, birds were trapped in standard mist nets. Our results suggest that juvenile dispersal of Reed Warblers takes place at night. The analysis of capture histories of ten birds ringed as pulli or just after fledging shows that: (1) age of birds during nocturnal movements was 33-49 days; (2) birds moved towards the NE and SW mainly during the last two hours before sunrise; (3) flight duration did not exceed 75 min; (4) all birds had low fuel stores and were in active moult; (5) nocturnal juvenile dispersal occurs by movements from one isolated reedbed area to another

Data from: Global lack of flyway structure in a cosmopolitan bird revealed by a genome wide survey of single nucleotide polymorphisms

Knowledge about population structure and connectivity of waterfowl species, especially mallards (Anas platyrhynchos), is a priority due to recent outbreaks of Avian Influenza. Ringing studies that trace large-scale movement patterns have to date been unable to detect clearly delineated mallard populations. We employed 363 single nucleotide polymorphism (SNP) markers in combination with population genetics and phylogeographic approaches to conduct a population genomic test of panmixia in 801 mallards from 45 locations world-wide. Basic population genetic and phylogenetic methods suggest no or very little population structure on continental scales. Nor could individual-based structuring algorithms discern geographical structuring. Model-based coalescent analyses for testing models of population structure pointed to strong genetic connectivity among the world’s mallard population. These diverse approaches all support the conclusion that there is a lack of clear population structure, suggesting that the world’s mallards, perhaps with minor exceptions, form a single large, mainly interbreeding population

Widespread horizontal genomic exchange does not erode species barriers among sympatric ducks

BACKGROUND:The study of speciation and maintenance of species barriers is at the core of evolutionary biology. During speciation the genome of one population becomes separated from other populations of the same species, which may lead to genomic incompatibility with time. This separation is complete when no fertile offspring is produced from inter-population matings, which is the basis of the biological species concept. Birds, in particular ducks, are recognised as a challenging and illustrative group of higher vertebrates for speciation studies. There are many sympatric and ecologically similar duck species, among which fertile hybrids occur relatively frequently in nature, yet these species remain distinct.RESULTS:We show that the degree of shared single nucleotide polymorphisms (SNPs) between five species of dabbling ducks (genus Anas) is an order of magnitude higher than that previously reported between any pair of eukaryotic species with comparable evolutionary distances. We demonstrate that hybridisation has led to sustained exchange of genetic material between duck species on an evolutionary time scale without disintegrating species boundaries. Even though behavioural, genetic and ecological factors uphold species boundaries in ducks, we detect opposing forces allowing for viable interspecific hybrids, with long-term evolutionary implications. Based on the superspecies concept we here introduce the novel term "supra-population" to explain the persistence of SNPs identical by descent within the studied ducks despite their history as distinct species dating back millions of years.CONCLUSIONS:By reviewing evidence from speciation theory, palaeogeography and palaeontology we propose a fundamentally new model of speciation to accommodate our genetic findings in dabbling ducks. This model, we argue, may also shed light on longstanding unresolved general speciation and hybridisation patterns in higher organisms, e.g. in other bird groups with unusually high hybridisation rates. Observed parallels to horizontal gene transfer in bacteria facilitate the understanding of why ducks have been such an evolutionarily successful group of animals. There is large evolutionary potential in the ability to exchange genes among species and the resulting dramatic increase of effective population size to counter selective constraints

Mallard SNP genotypes

Plain text file holding genoytpes of all analysed mallards