scholarly journals Migrating curlews on schedule: departure and arrival patterns of a long-distance migrant depend on time and breeding location rather than on wind conditions

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Philipp Schwemmer ◽  
Moritz Mercker ◽  
Klaus Heinrich Vanselow ◽  
Pierrick Bocher ◽  
Stefan Garthe

Abstract Background 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. Methods 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. Results 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. Conclusions 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.

2020 ◽  
Author(s):  
Philipp Schwemmer ◽  
Moritz Mercker ◽  
Klaus Heinrich Vanselow ◽  
Pierrick Bocher ◽  
Stefan Garthe

Abstract Background: 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.Methods: 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 migration. We obtained data for 42 migrations over 6 years, with 12 individuals performing repeat migrations in consecutive years. Departure and arrival dates were related to 73 meteorological and bird-related predictors using the least absolute shrinkage and selection operator (LASSO) to identify drivers of departure and arrival decisions.Results: 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.Conclusions: These results suggest that the trigger for migration in a 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.


2020 ◽  
Author(s):  
Philipp Schwemmer ◽  
Moritz Mercker ◽  
Klaus Heinrich Vanselow ◽  
Pierrick Bocher ◽  
Stefan Garthe

Abstract Background: Choosing the appropriate time to depart for spring migration is crucial to achieving a successful subsequent breeding season among migratory bird species. We expected Eurasian Curlews (Numenius arquata) to start their migration during favourable weather conditions and to adjust their flight heights to prevailing wind conditions.Methods: We equipped 23 curlews with Global Positioning System data loggers to record the spatio-temporal patterns of their departure from and arrival at their wintering site in the Wadden Sea, as well as the first part of their migration. We obtained data for 42 curlew migrations over a period of 6 years. Departure and arrival dates were related to 73 meteorological and bird-related predictors using the least absolute shrinkage and selection operator (LASSO) to identify drivers of departure and arrival decisions.Results: Curlews migrated almost exclusively to the western part of Russia for breeding. They left the Wadden Sea mainly during the evening hours 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, but males tended to return from their breeding sites later than females. Flight speeds of the birds increased significantly with increasing tailwind component, suggesting that they timed their migration according to favourable wind conditions. However, curlews left the Wadden Sea during various wind and weather conditions, with significant numbers leaving during headwind conditions, in contrast to the apparent wind-driven start of migration. Curlews migrated at very low altitudes during tailwind conditions, but flew significantly higher during headwind conditions, at altitudes of up to several kilometres. Departure dates varied by <4 days in individual curlews that were tagged over consecutive years. Conclusions: Our results suggest that the start of migration in a long-distance migrant mainly depends on the date and is independent of weather conditions. Given the high repeatability of the departure day among subsequent years, this clearly suggests the existence of an internal clock prompting the start of migration. Further insights into the timing of migration in immatures and closely related birds might help us to understand the genetic mechanisms triggering temporal migration patterns.


1970 ◽  
pp. 20-34 ◽  
Author(s):  
Imran A Dar ◽  
Mithas A Dar

The main thrust in this research work has been given on the evaluation of current status of Avifauna associated with Shallabug wetland. The main objectives were to evaluate the bird population fluctuation, to determine various threats to waterbirds and their habitats, and to present the remedial measures based on the key issues identified. For the purpose of present investigation, the study area was divided systematically into three study units of 700 m² each. Visual census method was used for the estimation of bird population. Visual counting was made with the help of high power field binocular (SG- 9.2) from respective vantage points. The birds were observed on the monthly basis in 2008 and the fluctuation in bird population was determined in different seasons: summer, autumn and winter.  The observations were made from 5:00 am to 7:00 am (when they come out from their resting place) and 6:00 pm to 7:00 pm (when they approach towards their resting place). The analysis of the results showed that the Shallabug Wetland is particularly important for migratory bird species and marsh land breeding species. The wetland was also found important for long distance migrants as a stopper site for feeding and resting. The bird population showed fluctuation with site differences as well as with changing seasons. Key words: Wetland, Shallabug, Avifauna, Fluctuation, Wetland managementDOI: 10.3126/jowe.v2i1.1853 Journal of Wetlands Ecology, (2009) vol. 2, pp 20-34


2011 ◽  
Vol 57 (3) ◽  
pp. 247-256 ◽  
Author(s):  
Reuven Yosef ◽  
Piotr Zduniak

The wryneck is an unusual representative of PalearcticPicidaein that it is a long-distance migrant, whose populations have declined across Europe in the last century. Israel is at the eastern extremes of the known wryneck migration routes in the spring, which are little studied. Hence, we studied the species migration patterns and staging at Eilat, the southern tip of Israel being a very important stopover site for many migratory bird species. During 28 springs and 25 autumn migration seasons in the years 1983-2010, a total of 588 wrynecks were trapped.The mean number of birds recorded per spring season was 18.32 (SE = 2.12) and only 3.00 ± 0.71 per autumn season. The analysis performed for spring passage showed that the mean proportion of juveniles to all birds to which ages were assigned was 48.9 ± 5.2%. Furthermore, we did not find any differences in the dates of ringing, wing length, body mass or body condition index of juvenile and adults. We retrapped 97 (18.9%) wrynecks during the spring. The average proportion retrapped per season was 18.3 ± 2.9% and the average stopover was 4.8 ± 0.4 days. Recaptured birds were in better body condition than at first capture, and the body condition index gained significantly during their stay at the stopover site. The low conservation priority accorded to these habitats — and ignored in spite of many studies from the reagion — highlights the importance of the preservation of priority areas such that avian and other migrations can continue with minimal human impact.


2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Florian Packmor ◽  
Thomas Klinner ◽  
Bradley K. Woodworth ◽  
Cas Eikenaar ◽  
Heiko Schmaljohann

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
José A. Alves ◽  
Maria P. Dias ◽  
Verónica Méndez ◽  
Borgný Katrínardóttir ◽  
Tómas G. Gunnarsson

Abstract Landbirds undertaking within-continent migrations have the possibility to stop en route, but most long-distance migrants must also undertake large non-stop sea crossings, the length of which can vary greatly. For shorebirds migrating from Iceland to West Africa, the shortest route would involve one of the longest continuous sea crossings while alternative, mostly overland, routes are available. Using geolocators to track the migration of Icelandic whimbrels (Numenius phaeopus), we show that they can complete a round-trip of 11,000 km making two non-stop sea crossings and flying at speeds of up to 24 m s−1; the fastest recorded for shorebirds flying over the ocean. Although wind support could reduce flight energetic costs, whimbrels faced headwinds up to twice their ground speed, indicating that unfavourable and potentially fatal weather conditions are not uncommon. Such apparently high risk migrations might be more common than previously thought, with potential fitness gains outweighing the costs.


2018 ◽  
Vol 6 (4) ◽  
pp. 124
Author(s):  
Antonella Giorgio ◽  
Salvatore De Bonis ◽  
Rosario Balestrieri ◽  
Giovanni Rossi ◽  
Marco Guida

Worldwide, bacteria are the most ubiquitous microorganisms, and it has been extensively demonstrated that migratory wild birds can increase bacterial global scale dispersion through long-distance migration and dispersal. The microbial community hosted by wild birds can be highly diverse, including pathogenic strains that can contribute to infections and disease spread. This study focused on feather and plumage bacteria within bird microbial communities. Samples were collected during ornithological activities in a bird ringing station. Bacterial identification was carried out via DNA barcoding of the partial 16S rRNA gene. Thirty-seven isolates of bacteria were identified on the chest feathers of 60 migratory birds belonging to three trans-Saharan species: Muscicapa striata, Hippolais icterina, and Sylvia borin. Our results demonstrate the possibility of bacterial transfer, including pathogens, through bird migration between very distant countries. The data from the analysis of plumage bacteria can aid in the explanation of phenomena such as migratory birds’ fitness or the development of secondary sexual traits. Moreover, these results have deep hygienic–sanitary implications, since many bird species have synanthropic behaviors during their migration that increase the probability of disease spread.


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