Individual shifts toward safety explain age-related foraging distribution in a gregarious shorebird

Although age-related spatial segregation is ubiquitous, the underlying mechanisms are poorly understood. Here, we aim to elucidate the processes behind a previously established age-related foraging distribution of red knots (Calidris canutus canutus) in their main wintering area in West Africa (Banc d’Arguin, Mauritania). Based on 10 years of observations of 1232 uniquely color-ringed individuals of 1 to 18+ years old, we examined whether the observed age-related foraging distribution resulted from 1) spatial differences in mortality or 2) age-related shifts in habitat use. Using multistate capture–recapture modeling, we showed that with age foraging red knots moved away from the shoreline, that is, to areas with fewer surprise attacks by raptors. Considering uncertainties in the subjective gradient in predation danger with increasing distance from shore (as assessed from correlations between vigilance and distance from shore in foraging birds), we applied 2 different danger zone boundaries, at 40 m and 500 m from shore. Between years, red knots had a much higher chance to move from the dangerous nearshore area to the “safe” area beyond (71–78% and 26% for 40-m and 500-m danger zone boundary, respectively), than vice versa (4% and 14%). For neither danger zone boundary value did we find differences in annual mortality for individuals using either dangerous or safe zone, so the move away from the shore with age is attributed to individual careers rather than differential mortality. We argue that longitudinal studies like ours will reveal that ontogenetic shifts in habitat use are more common than so far acknowledged

Changes in the waterbird community of the Parc National du Banc d'Arguin, Mauritania, 1980-2017

The Parc National du Banc d’Arguin in Mauritania hosts the largest concentrations of coastal waterbirds along the East Atlantic Flyway. In spite of this importance, a review of the changes in the numbers of waterbirds in the area is lacking since the first complete count in 1980. Here we analysed the seven complete waterbird counts made since then, and the additional yearly counts made in one subunit (Iwik region) since 2003.We present evidence for changes in the community composition of waterbirds over the past four decades. Total waterbird numbers showed a decrease between 1980 and 2017, with only Great White Pelican Pelecanus onocrotalus showing a significantincrease in numbers. Five species showed significant declines: Long-tailed Cormorant Phalacrocorax africanus, Red Knot Calidris canutus, Bar-tailed Godwit Limosa lapponica, Eurasian Curlew Numenius arquata, and Western Marsh Harrier Circus aeruginosus. In the remaining species, the variation in numbers between counts was too large, and the number of complete counts too small, for trends to be detected. The yearly counts at Iwik region also showed sharp decreases in the numbers of Red Knot, Bar-tailed Godwit, and Marsh Harrier, but not of Long-tailed Cormorant and Eurasian Curlew. A multivariate analysis revealed a significant effect of year on species composition, which was caused mainly by changes in the species depending on the intertidal mudflats for feeding (generally in decline) vs. the species depending on fish and crustaceans in the sublittoral and offshore zones (often showing increases)

Publisher correction:Resource landscapes explain contrasting patterns of aggregation and site fidelity by red knots at two wintering sites

[This corrects the article DOI: 10.1186/s40462-018-0142-4.].</p

Central-West Siberian-breeding Bar-tailed Godwits (<i>Limosa lapponica</i>) segregate in two morphologically distinct flyway populations

Long-distance migratory species often include multiple breeding populations, with distinct migration routes, wintering areas and annual-cycle timing. Detailed knowledge on population structure and migratory connectivity provides the basis for studies on the evolution of migration strategies and for species conservation. Currently, five subspecies of Bar-tailed Godwits Limosa lapponica have been described. However, with two apparently separate breeding and wintering areas, the taxonomic status of the subspecies L. l. taymyrensis remains unclear. Here we compare taymyrensis Bar-tailed Godwits wintering in the Middle East and West Africa, respectively, with respect to migration behaviour, breeding area, morphology and population genetic differentation in mitochondrial DNA. By tracking 52 individuals from wintering and staging areas over multiple years, we show that Bar-tailed Godwits wintering in the Middle East bred on the northern West-Siberian Plain (n = 19), while birds from West Africa bred further east, mostly on the Taimyr Peninsula (n = 12). The two groups differed significantly in body size and shape, and also in the timing of both northward and southward migrations. However, they were not genetically differentiated, indicating that the phenotypic (i.e. geographical, morphological and phenological) differences arose either very recently or without current reproductive isolation. We conclude that the taymyrensis taxon consists of two distinct populations with mostly non-overlapping flyways, which warrant treatment as separate taxonomic units. We propose to distinguish a more narrowly defined taymyrensis subspecies (i.e. the Bar-tailed Godwits wintering in West Africa and breeding on Taimyr), from a new subspecies (i.e. the birds wintering in the Middle East and breeding on the northern West-Siberian Plain)

Publisher Correction:Fuelling conditions at staging sites can mitigate Arctic warming effects in a migratory bird (Nature Communications, (2018), 9, 1, (4263), 10.1038/s41467-018-06673-5)

In the original HTML version of this Article, the order of authors within the author list was incorrect. The consortium VRS Castricum was incorrectly listed after Theunis Piersma and should have been listed after Cornelis J. Camphuysen. This error has been corrected in the HTML version of the Article; the PDF version was correct at the time of publication

Fuelling conditions at staging sites can mitigate Arctic warming effects in a migratory bird

Under climate warming, migratory birds should align reproduction dates with advancing plant and arthropod phenology. To arrive on the breeding grounds earlier, migrants may speed up spring migration by curtailing the time spent en route, possibly at the cost of decreased survival rates. Based on a decades-long series of observations along an entire flyway, we show that when refuelling time is limited, variation in food abundance in the spring staging area affects fitness. Bar-tailed godwits migrating from West Africa to the Siberian Arctic reduce refuelling time at their European staging site and thus maintain a close match between breeding and tundra phenology. Annual survival probability decreases with shorter refuelling times, but correlates positively with refuelling rate, which in turn is correlated with food abundance in the staging area. This chain of effects implies that conditions in the temperate zone determine the ability of godwits to cope with climate-related changes in the Arctic

Первая находка тонкоклювого буревестника В западном секторе российской арктики

А dead male Short-tailed Shearwater was found on 25 June 2019 on the tundra 4 km away from the coast of the Knipovich Bay, northern Taimyr Peninsula (76°05′18″ N, 98°26′29″ E). It is the first record of this speciesin the western sector of the Russian Arctic

Roodsnavelkeerkringvogel Phaethon aethereus in Nederland

Een op Texel gevonden dode roodsnavelkeerkringvogel was de reden de twee Nederlandse vondsten te bespreken. De aandacht voor de soort leverde bovendien een zichtwaarneming van een langsvliegend exemplaar in Nederland op die nog niet eerder algemeen bekend was. De Nederlandse keerkringvogels zijn ook in het licht van andere Noordwest-Europese gevallen beschouwd. Dit betreft vier dode en tien levende exemplaren. De dode komen uit het winterhalfjaar, de levende uit het zomerhalfjaar. Mogelijk zijn de dode vogels met schepen aangevoerd