Bird migration in space and time: chain migration by Eurasian curlew Numenius arquata arquata along the East Atlantic Flyway

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

Invertebrate abundance increases with vegetation productivity across natural and agricultural wader breeding habitats in Europe

Grassland breeding waders have been steadily declining across Europe. Recent studies indicating a dramatic decline in grassland invertebrates' abundance and biomass, the key food of most grassland wader chicks, suggest a likely driver of the demise of waders. While agricultural intensification is generally inferred as the main cause for arthropod decline there is surprisingly little information on the relationship between land use intensity and total arthropod abundance in grasslands. Here, we explored those relationships across several key wader breeding habitats by surveying ground-active, aerial and soil-dwelling invertebrate communities in five European countries that range from natural undisturbed bogs to intensively managed grasslands. Using maximum vegetation growth and soil moisture content we investigated how they shape the size of the invertebrate community within and across different countries. We found predominantly positive relationships between grassland invertebrate abundance, biomass and body weight with increasing vegetation growth and soil moisture. Maximum vegetation growth was strongly positively related to ground-active invertebrate abundance and biomass and abundance of soil dwelling invertebrates (mainly earthworms). Body weight of aerial invertebrates furthermore increased with increasing maximum vegetation growth. Our results provide little support for the hypothesis that agricultural practices associated with intensification of grassland management result in an abundance decline of invertebrate prey for wader chicks. Conservation practices aiming to enhance wader chick survival require a careful balancing act between maintaining habitat productivity to secure high prey abundance, and keeping productivity low enough to maintain open swards that do not need to be cut before chicks have fledged

Blankaartia acuscutellaris (Walch, 1922) (Actinotrichida: Trombiculidae) collected from the great snipe Gallinago media (Latham, 1787) (Charadriformes: Scolopacidae) in Poland – new host and country record for chigger mite genus and species

International audienceThe parasitic chigger mite, Blankaartia acuscutellaris, collected from a female of Gallinago media is recorded from Poland for the first time. The locality, which constitutes the northernmost record of B. acuscutellaris in the Palaearctic, raises the question of possibility of establishing a new population on the verges of the species’ distribution range. Metric data for larvae, extending the knowledge of intra-specific variation, are provided

Cross-continental differences in Black-tailed Godwit breeding densities are best explained by arthropod abundance in the chick-hatching period

The endangered continental Black-tailed Godwit (Limosa limosa limosa) is a migratory ground-nesting wader breeding in a wide variety of open, wet habitats across Europe. Conservation research has concentrated on the causes of population decline, but we know surprisingly little about whether any resources limit local breeding populations and if so, whether these are resources for the adults or the chicks. We collected data from 63 key breeding sites in five countries across Europe to test whether, after correcting for differences in surveyed areas, the size of Godwit breeding populations was related to environmental variables (vegetation biomass, soil moisture) or food resources for adult birds (soil invertebrates) or chicks (vegetation dwelling arthropods) measured during different times of the reproductive cycle. We found the number of Godwit territories to be positively related to arthropod abundance during the chick-hatching period. We found additional, weaker support for a positive relation between Godwit territory numbers and the abundance of soil-dwelling invertebrates (mostly earthworms) at clutch laying, but not at chick-hatching. These relationships were observed across countries, while we found little support for relationships within countries, possibly due to the smaller range in conditions that exist within countries. Both vegetation growth and soil moisture weren’t related to Godwit territory numbers. Our results suggest that food abundance for chicks, and to a lesser extent adult birds, are key factors determining the size of local Godwit breeding populations. Conservation management aiming to enhance local Godwit populations should therefore consider the impacts of management strategies on the arthropod prey of chicks

Cross-continental differences in Black-tailed Godwit breeding densities are best explained by arthropod abundance in the chick-hatching period

The endangered continental Black-tailed Godwit (Limosa limosa limosa) is a migratory ground-nesting wader breeding in a wide variety of open, wet habitats across Europe. Conservation research has concentrated on the causes of population decline, but we know surprisingly little about whether any resources limit local breeding populations and if so, whether these are resources for the adults or the chicks. We collected data from 63 key breeding sites in five countries across Europe to test whether, after correcting for differences in surveyed areas, the size of Godwit breeding populations was related to environmental variables (vegetation biomass, soil moisture) or food resources for adult birds (soil invertebrates) or chicks (vegetation dwelling arthropods) measured during different times of the reproductive cycle. We found the number of Godwit territories to be positively related to arthropod abundance during the chick-hatching period. We found additional, weaker support for a positive relation between Godwit territory numbers and the abundance of soil-dwelling invertebrates (mostly earthworms) at clutch laying, but not at chick-hatching. These relationships were observed across countries, while we found little support for relationships within countries, possibly due to the smaller range in conditions that exist within countries. Both vegetation growth and soil moisture weren’t related to Godwit territory numbers. Our results suggest that food abundance for chicks, and to a lesser extent adult birds, are key factors determining the size of local Godwit breeding populations. Conservation management aiming to enhance local Godwit populations should therefore consider the impacts of management strategies on the arthropod prey of chicks

Invertebrate abundance increases with vegetation productivity across natural and agricultural wader breeding habitats in Europe

Abstract Grassland breeding waders have been steadily declining across Europe. Recent studies indicating a dramatic decline in grassland invertebrates’ abundance and biomass, the key food of most grassland wader chicks, suggest a likely driver of the demise of waders. While agricultural intensification is generally inferred as the main cause for arthropod decline there is surprisingly little information on the relationship between land use intensity and total arthropod abundance in grasslands. Here, we explored those relationships across several key wader breeding habitats by surveying ground-active, aerial and soil-dwelling invertebrate communities in five European countries that range from natural undisturbed bogs to intensively managed grasslands. Using maximum vegetation growth and soil moisture content we investigated how they shape the size of the invertebrate community within and across different countries. We found predominantly positive relationships between grassland invertebrate abundance, biomass and body weight with increasing vegetation growth and soil moisture. Maximum vegetation growth was strongly positively related to ground-active invertebrate abundance and biomass and abundance of soil dwelling invertebrates (mainly earthworms). Body weight of aerial invertebrates furthermore increased with increasing maximum vegetation growth. Our results provide little support for the hypothesis that agricultural practices associated with intensification of grassland management result in an abundance decline of invertebrate prey for wader chicks. Conservation practices aiming to enhance wader chick survival require a careful balancing act between maintaining habitat productivity to secure high prey abundance, and keeping productivity low enough to maintain open swards that do not need to be cut before chicks have fledged