Little is known on the food and feeding ecology of the soft-plumaged petrel
Pterodroma mollis
, which is the single gadfly petrel
Pterodroma
spp. with a circumpolar breeding distribution within the ...Southern Ocean. Our primary goal was to describe its diet at Kerguelen Islands, which is the southernmost breeding locality of the species. Soft-plumaged petrels fed on fish (71% by mass), and secondarily on crustaceans (22%), while cephalopods (7%) and other items (< 1%) were minor dietary components. Eight-hundred and sixty prey were identified from the pooled 33 food samples, with the 2 hyperiid amphipods
Cyllopus magellanicus
(48%) and
Themisto gaudichaudii
(35%) being the main food items by number. Owing to their larger size than crustaceans, mesopelagic fishes were the main prey by mass, with myctophids being the most important fish family in terms of both abundance (68% of the fish) and diversity (10 species). Prey distribution indicated that soft-plumaged petrels foraged primarily in oceanic subantarctic waters to feed their chicks. The oceanic life style of gadfly petrels was then highlighted by a review of their diet worldwide (20 species, 26 studies). Gadfly petrels prey mainly upon mesopelagic fishes (chiefly myctophids) and squids with their relative proportions depending on species and localities. Crustaceans are minor food items for tropical species, but they form a significant part of the food of the small- and medium-sized petrels that live in temperate and cold waters. The review underlines the need for more well-designed investigations on this globally endangered group of seabirds, since dietary information is available for only 57% of the 35 species of gadfly petrels.
Migratory shorebird populations are declining worldwide, showing an apparent inability to respond to the interplaying challenges emerging along their flyways. Within the East Atlantic Flyway, ...non-breeding populations show moderate to strong declines in Sub-Saharan Africa, contrasting with stable or increasing trends in Europe. Local factors are insufficient to explain the opposite tendencies and, therefore, investigating migratory strategies and connectivity of these populations may help identifying the drivers of their demography. We followed the migratory journeys of 20 grey plovers (Pluvialis squatarola) from their wintering grounds in Guinea-Bissau (West Africa), Portugal and France (Europe) using tracking devices. Grey plovers wintering in Africa and Europe were found to share breeding grounds at European Russia and Western Siberia, revealing low migratory connectivity in the Eastern Atlantic population. All individuals followed a "skipping" migratory strategy, flying mostly mid-distance bouts, and using an unexpected large network of stopover sites to re-fuel usually for short periods. We identified 66 different stopover sites along the West African, European and Russian/Siberian coasts. All birds stopped at the Wadden Sea in both migratory periods, highlighting the importance of this region and the risk for a potential bottleneck. Low migratory connectivity and similar migratory strategies shared by grey plovers wintering in Europe and West Africa do not support their contrasting population trends.
The Eurasian Curlew is an endangered long-lived shorebird breeding in grassland and moorland, with declining numbers across its range due to habitat loss and former hunting. In this context, any ...additional adult mortality can have a noticeable impact on population dynamics, hence on extinction risk. We report a case of a GPS-tagged individual which track revealed an unusual stopover at the bottom of a wind turbine along its migration route. The curlew rested hours in an unfavourable environment before moving to the adjacent coastal shore, then completed its migration journey the next day. In previous studies, GPS-tags helped to identify death casualties at wind farms, but to our knowledge this is the first detailed report of a non-lethal injury of a tagged animal by a wind turbine, probably by the vortex of rotors. This case alerts on the further potential impacts of wind farm development close to breeding, wintering and stopover sites frequented by Eurasian curlews and other birds. Any wind farm development project should consider the opportunity to avoid, reduce or compensate potential lethal and non-lethal impacts on wildlife.
•We document how a GPS-tagged migratory Eurasian Curlew interacted with a wind turbine.•Data collected by the GPS tag prove that the bird trajectory stopped at a wind turbine.•The outcome of the interaction was non-lethal as the Eurasian curlew completed its migratory journey the next day.•Eurasian Curlew is globally threatened due to widespread declines in breeding populations, so that assessment of all potential threats to adult survival is important.
Migration patterns in birds vary in space and time. Spatial patterns include chain, leapfrog and telescopic migration. Temporal patterns such as migration duration, number, and duration of stopovers ...may vary according to breeding latitude, sex, and season. This study aimed to verify these patterns in a long‐distance migrant, the Eurasian curlew Numenius arquata arquata, and to provide a synopsis of spatio‐temporal migration patterns in this species of concern throughout the East Atlantic Flyway. We tagged 85 adults with GPS‐data loggers in Germany, Poland, France and Estonia between 2013 and 2019. We computed the distance flown, linear loxodromic distance, duration, stopover number, total stopover duration, mean stopover duration, departure time and arrival time for 177 out of 187 tracks. On average (± standard deviation), spring migration occurred from 4 to 14 April (10.2 ± 8.4 days), curlews flew 3.623 ± 1.366 km, and had 5.8 ± 3.6 stopovers, with a duration of 29.4 ± 38.2 h per stopover, while autumn migration occurred from 18 to 29 June (10.9 ± 9.9 days), curlews flew 3.362 ± 1.351 km, and had 5.4 ± 4.0 stopovers, with 31.8 ± 32.3 h per stopover. Curlews displayed chain migration because wintering curlews maintained the latitudinal sequence to their breeding sites. Southern curlews had a longer nesting period due to their earlier arrivals. While spring arrival at breeding sites did not differ between the sexes, in autumn females departed earlier than males. Migration duration and distance, as well as stopover number and duration, showed a significant increase with breeding site latitude but did not differ between the sexes or between spring and autumn migrations, suggesting that curlews took a comparable amount of time migrating during both seasons. The high site faithfulness in curlews suggests that rapid autumn migration allows them to return to defend their winter foraging areas.
Departure decisions in long-distance migratory bird species may depend on favourable weather conditions and beneficial resources at the destination location, overarched by genetic triggers. However, ...few studies have tried to validate the significance of these three concepts simultaneously, and long-term, high-resolution tagging datasets recording individual movements across consecutive years are scarce. We used such a dataset to explore intraspecific and intra-individual variabilities in departure and arrival decisions from/to wintering grounds in relation to these three different concepts in bird migration.
We equipped 23 curlews (Numenius arquata) wintering in the Wadden Sea with Global Positioning System data loggers to record their spatio-temporal patterns of departure from and arrival at their wintering site, and the first part of their spring migration. We obtained data for 42 migrations over 6 years, with 12 individuals performing repeat migrations in consecutive years. Day of year of departure and arrival was related to 38 meteorological and bird-related predictors using the least absolute shrinkage and selection operator (LASSO) to identify drivers of departure and arrival decisions.
Curlews migrated almost exclusively to Arctic and sub-Arctic Russia for breeding. They left their wintering site mainly during the evening from mid- to late April and returned between the end of June and mid-July. There was no difference in departure times between the sexes. Weather parameters did not impact departure decisions; if departure days coincided with headwind conditions, the birds accounted for this by flying at higher altitudes of up to several kilometres. Curlews breeding further away in areas with late snowmelt departed later. Departures dates varied by only < 4 days in individual curlews tagged over consecutive years.
These results suggest that the trigger for migration in this long-distance migrant is largely independent of weather conditions but is subject to resource availability in breeding areas. The high intra-individual repeatability of departure days among subsequent years and the lack of relationship to weather parameters suggest the importance of genetic triggers in prompting the start of migration. Further insights into the timing of migration in immatures and closely related birds might help to further unravel the genetic mechanisms triggering migration patterns.
Many farmland birds, such as the Eurasian Curlew (Numenius arquata; here in after Curlew), are in steep decline. So far, decreased reproduction and, hence, an insufficient number of offspring to ...compensate for adult mortality has been considered the main driver of the recent population collapse. However, despite extensive conservation measures in most breeding areas, there are no signs of a general reversal of the population trend. Accordingly, conservation has to focus on decreasing adult mortality outside the breeding areas as well. For Curlews breeding in NW Germany, ring recoveries suggest that the main wintering areas are the coastlines of western France and southern England. However, such data are often biased in space and time. Here, we used GPS tracking to investigate the wintering areas and post-breeding migration of Curlews of the main German breeding population based on large sample size. Altogether, we tagged 86 adult breeding birds at 23 subareas across a transect of about 250 km (in length) in NW Germany. Curlews started post-breeding migration right after finishing breeding or attempting to breed, which was mainly in mid-June. We identified the coastlines of Great Britain/Ireland, western France and the Netherlands, in particular the Rhine-Meuse-Delta and the Wadden Sea, as the main wintering areas of Curlews breeding in NW Germany. We found a latitudinal structuration of migration, with birds nesting further north using more northerly wintering areas. However, in some cases, wintering areas of birds of the same subpopulation were located more than a thousand kilometres apart from each other. All three main stopover areas identified by our study (German/Dutch Wadden Sea, Dutch Rhine-Meuse-Delta, French Normandy) overlap in large parts with the main wintering areas. Since Curlews spend most of the year outside their breeding areas, and wintering and stopover areas also suffer from rapid environmental change, conservation has to additionally focus on these areas. Nearly one third (29%) of the tracked birds wintered in France or used French stopover areas. Accordingly, they might potentially be affected by a resumption of hunting, which is currently in discussion in France. Our study provides an important basis for the protection of wintering and stopover areas of the main German breeding population but also for other wader species migrating along the East Atlantic Flyway.
Display omitted
•Identification of wintering and stopover areas of Curlews breeding in NW-Germany.•Main wintering areas based on GPS tracking: coastlines of GB/IR, western FR and NL.•Geographical latitude of nesting sites was related to latitude of wintering areas.•Main stopover areas overlapped in large parts with main wintering areas.•One third of the population could be affected by resumption of hunting in France.
The Freshwater Animal Diversity Assessment (FADA) project estimated that freshwater animal species represent 9.5% of the 1.2 million species described. Knowing that freshwater represents only 0.01% ...of the earth's surface, these wetlands are suitable habitats for a great part of the world's total biodiversity. However, it has been shown that there is a lack of knowledge on these species, including freshwater invertebrates. Nevertheless, they play a key role in the majority of freshwater ecosystems and in their foodweb networks. Freshwater invertebrates are the food resource of many species, such as fish and birds. The knowledge of their morphological, energetic and nutritive characteristics allows a better understanding of their selection by predators (size, energy intake etc.), but also leads to the improvement of wetland management. Although information about freshwater invertebrates exists in literature, they are generally heterogeneous, dispersed and difficult to collect. To facilitate the accessibility of these data and, thus, optimise and accelerate research projects including freshwater invertebrates, we propose a literature review describing 14 morphological and nutritive characteristics (size, dry weight, gross energy, crude protein etc.) for 656 taxa of freshwater invertebrates.
This dataset is a review from 104 publications from 1935 to 2020, compiling 14 characteristics when available (size, dry weight, gross energy, crude protein etc.) for 656 taxa of freshwater invertebrates.
In ecological systems, it is necessary to describe the trophic niches of species and their segregation or overlap to understand the distribution of species in the community. In oceanic systems, the ...community structure of top predators such as seabird communities has been well documented with many studies in several biogeographical areas. But for coastal habitats, very few investigations on the trophic structure have been carried out in avian communities. In this study, the trophic resource partitioning was investigated on eight of the most abundant species of a shorebird community on the central Atlantic coast of France. Our work comprised a comprehensive sample of birds with different ecomorphogical patterns and data on their main prey to encompass potential sources of overlap and segregation in this community. We examined the stable carbon (δ13C) and nitrogen (δ15N) isotopic composition of blood to investigate the trophic structure (1) on a temporal scale by comparing migration and wintering periods; (2) on a spatial scale through inter-site comparisons; and (3) on the community level within groups of phylogenetically related species. Diets appeared different in several cases between periods, between sites and between juveniles and adults for the same sites. A clear trophic partitioning was established with four functional groups of predators in winter inside the community. The Grey Plover, the Bar-tailed Godwit, the Curlew and a majority of the dunlins were worm-eaters mainly feeding on Nereis diversicolor or Nephtys hombergii. Two species were predominantly deposit-suspensivorous mollusc-eaters, including the Red Knot and the Black-tailed Godwit feeding mainly on Macoma balthica. The Oystercatcher fed mainly on suspensivorous molluscs like Cerastodrema edule and two species including the Redshank and some dunlins adopted opportunistic behaviours feeding on mudflat and/or in marshes.
•We examine the trophic resource partitioning among eight shorebird species.•We examine the trophic structure by stable carbon and nitrogen isotopic in blood.•A clear trophic partitioning was established with four functional groups.•Differences in isotopic signatures between juveniles and adults are largely variable.•Not only strictly marine diets were observed but some completed by terrestrial prey.
Habitat selection is an important process in birds that influences individual survival and fitness, and ultimately shapes population dynamics. As a consequence, strong selective pressures apply to ...favor strategies allowing individuals to choose high-quality habitat for foraging while reducing predation risk and competition. In long-distance migratory birds, such as shorebirds, the non-breeding period is considered as a key period of their annual cycle with reported effects on individual survival and subsequent reproduction. Site selection by non-breeding shorebirds should depend on habitat quality for them to ensure survival until the next breeding season. More specifically, birds should distribute in space and time according to their resource availability and specialize on feeding habitats or/and prey to reduce intraspecific competition. To test this hypothesis, we studied Bar-tailed Godwits (
Limosa lapponica
) at one of their main non-breeding sites along the French coast. We first used GPS tracking to investigate their foraging and roosting home ranges as well as core sampling to define the diversity of available habitats and their quality as feeding resources. We then compared individual habitat selection in relation to feeding home range sizes and benthic macrofauna abundances. Our results provide the first fine scale definition of shorebird movements and distribution along the non-breeding period. We found that godwits showed an extreme fidelity to restricted feeding areas (about 3.4 km
2
) during winter, with low overlap between individual feeding home ranges. Each bird appeared to mainly use 4–6 of the 11 available foraging habitats, with a specialization on 1 to 2 main habitats and their associated prey. However, our results did not emphasize a clear relationship between home range sizes and the quality of bird feeding sites. This study thus demonstrates the high specialization of individual non-breeding Bar-tailed godwits relying on specific foraging grounds and habitats, with important implications for the conservation of this species.
Farmland birds are among the most threatened species in Europe, largely as a result of the intensification of agriculture leading to widespread biodiversity losses. Ground-breeding shorebirds in ...grassland and arable habitats are particularly exposed to human threats and predation in highly modified landscapes; however, parts of their populations still breed in natural habitats and could provide a reservoir for threatened populations. This study aimed to improve our knowledge of the spatio-temporal use of breeding habitats by Eurasian curlew Numenius arquata arquata in a core area of the population in remote north-eastern Europe. A total of 83 adult birds across Europe were tagged with GPS devices between 2014 and 2022 to analyse their home-range sizes, habitat use and hatching success. Birds were distributed at breeding sites from 52°N to 66°N between Finland and the Ural Mountains. Forty-one percent of individuals nested in bogs, 33% in grassland, and 20% in abandoned farmland. Birds nested predominantly in bogs at northern latitudes and in grassland at southern latitudes, while abandoned farmland was mainly used at intermediate latitudes. The mean home range was largest for birds breeding predominantly in grassland while birds in bogs had the highest hatching success rate. Russia and Finland host the core population of the subspecies N. a. arquata during breeding period, which is essential for preserving the species on a European scale. Their survival may depend on well-preserved bogs and the maintenance of grassland areas, given that large areas of abandoned farmland are destined to become either forest or to be reclaimed for cereal crops or fodder grass in the short and medium terms. Given the large breeding populations in both countries, Russia and Finland have major responsibilities to maintain these essential populations on a biogeographical scale.
•Abandoned farmlands are important breeding habitats for shorebirds.•Breeding success is higher for curlews breeding in bogs than in grasslands.•Home range sizes and shapes depend on fragmentation of landscape around nests.•Breeding phenology depends on breeding latitude in east-northern Europe.
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