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Senner N.R.,Cornell University | Senner N.R.,University of Groningen | Hochachka W.M.,Cornell University | Fox J.W.,British Antarctic Survey | And 2 more authors.
PLoS ONE | Year: 2014

Recent years have seen a growing consensus that events during one part of an animal's annual cycle can detrimentally affect its future fitness. Notably, migratory species have been shown to commonly display such carry-over effects, facing severe time constraints and physiological stresses that can influence events across seasons. However, to date, no study has examined a full annual cycle to determine when these carry-over effects arise and how long they persist within and across years. Understanding when carry-over effects are created and how they persist is critical to identifying those periods and geographic locations that constrain the annual cycle of a population and determining how selection is acting upon individuals throughout the entire year. Using three consecutive years of migration tracks and four consecutive years of breeding success data, we tested whether carry-over effects in the form of timing deviations during one migratory segment of the annual cycle represent fitness costs that persist or accumulate across the annual cycle for a long-distance migratory bird, the Hudsonian godwit, Limosa haemastica. We found that individual godwits could migrate progressively later than population mean over the course of an entire migration period, especially southbound migration, but that these deviations did not accumulate across the entire year and were not consistently detected among individuals across years. Furthermore, neither the accumulation of lateness during previous portions of the annual cycle nor arrival date at the breeding grounds resulted in individuals suffering reductions in their breeding success or survival. Given their extreme life history, such a lack of carry-over effects suggests that strong selection exists on godwits at each stage of the annual cycle and that carry-over effects may not be able to persist in such a system, but also emphasizes that high-quality stopover and wintering sites are critical to the maintenance of long-distance migratory populations. © 2014 Senner et al.


Schmaljohann H.,Institute of Avian Research Vogelwarte Helgoland | Buchmann M.,Unterer Sand 12 | Fox J.W.,Migrate Technology Ltd. | Bairlein F.,Institute of Avian Research Vogelwarte Helgoland
Behavioral Ecology and Sociobiology | Year: 2012

Movement ecology studies have highlighted the importance of individual-based research. As tracking devices have not been applicable for identifying year-around movements of small birds until recently, migration routes of such species relied on visual observations and ring recoveries. Within the Palaearctic-African migration system, loop migration seems to be the overall migration pattern. The interindividual variations within species-specific migration routes are, however, unknown. Here, we track the individual migration routes and annual cycles of male Northern Wheatears Oenanthe oenanthe, a trans-Sahara songbird migrant from a German breeding population with light-level geolocators. Two migrated most likely via Spain towards western Africa but returned via Corsica/Sardinia, while two others seemed to migrate via Sardinia and Corsica in autumn and via Spain and France in spring (loop migration). The fifth took presumably the same route via France and the Balearics in both seasons. All birds wintered in the Sahel zone of western Africa. Overall migration distances for autumn and spring were similar (about 4,100 km), whereas the overall migratory speed was generally higher in spring (126 km day-1) than in autumn (88 km day-1). Birds spent about 130 days at the breeding area and 147 days at the wintering grounds. © 2012 Springer-Verlag.


Schmaljohann H.,Institute of Avian Research Vogelwarte Helgoland | Fox J.W.,Migrate Technology Ltd | Bairlein F.,Institute of Avian Research Vogelwarte Helgoland
Animal Behaviour | Year: 2012

Migrants' responses to varying meteorological and magnetic conditions and their consequent costs in terms of energy and time are crucial for the understanding of the spatial principles guiding migration. Until now, studies of birds' phenotypic responses to environmental conditions and estimated costs of migration in terms of energy and time have focused on single sites and have rarely followed individuals along entire migration routes. We used individual-based light level geolocators to track birds' daily phenotypic responses to the environmental conditions experienced along a 30 000. km migration between Alaska and Africa. In autumn, departures of northern wheatears, Oenanthe oenanthe, were highly dependent on low temperatures and light winds but there was no such apparent dependence in spring. Migration was 1.4-times faster in spring than in autumn. There was an unexpected shift in the ratio of migration:stopover time towards less stopover time in spring, reducing spring's total energy costs for migration with respect to distance covered by nearly 50% in comparison to autumn. Despite strong changes in declination during migration, offering near-experimental conditions, birds did not navigate exclusively along any major compass course. In contrast to expectations, these high-Arctic migrants did not follow great circle routes; their hypothetical energetic benefit (ca. 20% for flying) might be insufficient and conditions for orientation too unfavourable to favour its evolution. © 2012 The Association for the Study of Animal Behaviour.


Solovyeva D.V.,Russian Academy of Sciences | Afanasiev V.,Natural Environment Research Council | Fox J.W.,Natural Environment Research Council | Fox J.W.,Migrate Technology Ltd | And 2 more authors.
Endangered Species Research | Year: 2012

We determined, for the first time, individual linkages between breeding areas of nesting female scaly-sided mergansers Mergus squamatus in the Russian Far East and their previously unknown wintering grounds in coastal Korea and inland China. Geolocators were deployed on nesting females caught and recaptured on nests along a 40-km stretch of the Kievka River. Mean positions for brood-rearing females during the summer were on average within 61.9 km of the nest site, suggesting reasonable device accuracy for subsequent location of winter quarters. Geolocation data showed that most birds wintered on freshwater habitats throughout mainland China, straddling an area 830 km E-W and 1100 km N-S. Most wintered in discrete mountainous areas with extensive timber cover, large rivers and low human population density. Three birds tracked in more than one season returned to within 25-150 km of previous wintering areas in successive years, suggesting winter fidelity to catchments if not specific sites. A single female from the adjacent Avvakumovka catchment wintered on saltwater in Korea, at least 1300 km east of Chinese wintering birds. Most sea duck species (Tribe Mergini) form pairs away from breeding areas, suggesting that this high level of winter dispersal amongst close-nesting females is a potential mechanism to maintain gene flow in this threatened species that has specialist habitat requirements. Hence, female scaly-sided mergansers disperse widely from breeding areas, but show fidelity to nesting areas and winter quarters. © Inter-Research 2012.


Eraud C.,Office National de la Chasse et de la Faune Sauvage | Riviere M.,Maisonneuve | Lormee H.,Office National de la Chasse et de la Faune Sauvage | Fox J.W.,Migrate Technology Ltd | And 2 more authors.
PLoS ONE | Year: 2013

The identification of migration routes, wintering grounds and stopover sites are crucial issues for the understanding of the Palearctic-African bird migration system as well as for the development of relevant conservation strategies for trans-Saharan migrants. Using miniaturized light-level geolocators we report a comprehensive and detailed year round track of a granivorous trans-Saharan migrant, the European Turtle Dove (Streptopelia turtur). From five recovered loggers, our data provide new insights on migratory journeys and winter destinations of Turtle Doves originating from a breeding population in Western France. Data confirm that Turtle Doves wintered in West Africa. The main wintering area encompassed Western Mali, the Inner Delta Niger and the Malian/Mauritanian border. Some individuals also extended their wintering ranges over North Guinea, North-West of Burkina Faso and the Ivory-Coast. Our results reveal that all individuals did not spend the winter period at a single location; some of them experienced a clear eastward shift of several hundred kilometres. We also found evidence for a loop migration pattern, with a post-breeding migration flyway lying west of the spring route. Finally, we found that on their way back to breeding grounds Turtle Doves needed to refuel after crossing the Sahara desert. Contrary to previous suggestions, our data reveal that birds used stopover sites for several weeks, presumably in Morocco and North Algeria. This later finding is a crucial issue for future conservation strategies because environmental conditions on these staging areas might play a pivotal role in population dynamics of this declining species. © 2013 Eraud et al.


Jahn A.E.,University of Florida | Jahn A.E.,University of Buenos Aires | Levey D.J.,University of Florida | Levey D.J.,National Science Foundation | And 6 more authors.
Auk | Year: 2013

Little is known about the timing of migration, migration routes, and migratory connectivity of most of the >230 species of birds that breed at south temperate latitudes of South America and then migrate toward the tropics to overwinter. We used light-level geolocators to track the migration of 3 male and 3 female Fork-tailed Flycatchers (Tyrannus savana) captured on their breeding territories in Argentina. All birds initiated fall migration between late January and late February, and migrated 45 to 66 km day-1 in a northwesterly direction through central South America to either one or two wintering areas. Five individuals first spent several weeks (in April and May) in western Amazonia (mainly Peru, northwestern Brazil, and southern Colombia) before moving east to spend the rest of the non-breeding season in central Venezuela and northern Brazil. One individual occupied primarily one wintering area in eastern Colombia, northwestern Brazil, and southwestern Venezuela. Fall migration took approximately 7-12 weeks to complete and covered a distance of 2,888-4,105 km. We did not analyze spring migration data because of broad overlap with the austral spring equinox. These results are the first data on wintering locations, migration timing, and routes of individual migrant passerine birds that breed in South America. Given the general lack of similar data for practically all migratory birds that breed in South America, geolocator technology has the potential to revolutionize our understanding of how birds migrate-and the threats they face-on South America's rapidly changing landscape. © 2013 by The American Ornithologists' Union. All rights reserved.


Beason J.P.,Rocky Mountain Bird Observatory | Gunn C.,P. O. Box 791 | Potter K.M.,White River National Forest | Sparks R.A.,Rocky Mountain Bird Observatory | And 2 more authors.
Wilson Journal of Ornithology | Year: 2012

Winter ranges have been identified for most neotropical migrant bird species, those that spend the winter months in Central and South America and summer months in North America. Published accounts and specimen collections of the Northern Black Swift (Cypseloides niger borealis) during spring and fall migration are extremely limited and winter records are nonexistent. We placed light-level geolocators on four Black Swifts in August 2009, and retrieved three a year later. Data from the geolocators revealed initiation of fall migration (10 to 19 Sep 2009), arrival dates at wintering areas (28 Sep to 12 Oct 2009), departure dates from wintering areas (9 to 20 May 2010), and return dates to breeding sites (23 May to 18 Jun 2010) for Northern Black Swifts breeding in interior North America (Colorado, USA). Northern Black Swifts traveled 6,901 km from the Box Canyon breeding site and 7,025 km from Fulton Resurgence Cave to the center of the wintering area. The swifts traveled at an average speed of 341 km/day during the 2009 fall migration and an average speed of 393 km/day during the 2010 spring migration. This is the first evidence that western Brazil is the wintering area for a subset of the Northern Black Swift, extending the known winter distribution of this species to South America. © 2012 by the Wilson Ornithological Society.


Delmore K.E.,University of British Columbia | Fox J.W.,British Antarctic Survey | Fox J.W.,Migrate Technology Ltd | Irwin D.E.,University of British Columbia
Proceedings of the Royal Society B: Biological Sciences | Year: 2012

Migratory divides are contact zones between breeding populations that use divergent migratory routes and have been described in a variety of species. These divides are ofmajor importance to evolution, ecology and conservation but have been identified using limited band recovery data and/or indirect methods. Data from band recoveries and mitochondrial haplotypes suggested that inland and coastal Swainson's thrushes (Catharus ustulatus) form a migratory divide in western North America. We attached light-level geolocators to birds at the edges of this contact zone to provide, to our knowledge, the first direct test of a putative divide using data from individual birds over the entire annual cycle. Coastal thrushes migrated along the west coast to Mexico, Guatemala and Honduras. Some of these birds used multiple wintering sites. Inland thrushes migrated across the Rocky Mountains, through central North America to Columbia and Venezuela. These birds migrated longer distances than coastal birds and performed a loop migration, navigating over the Gulf of Mexico in autumn and around this barrier in spring. These findings support the suggestion that divergent migratory behaviour could contribute to reproductive isolation betweenmigrants, advance our understanding of their non-breeding ecology, and are integral to development of detailed conservation strategies for this group. © 2012 The Royal Society.


Tottrup A.P.,Copenhagen University | Klaassen R.H.G.,Lund University | Strandberg R.,Lund University | Thorup K.,Copenhagen University | And 7 more authors.
Proceedings of the Royal Society B: Biological Sciences | Year: 2012

The small size of the billions of migrating songbirds commuting between temperate breeding sites and the tropics has long prevented the study of the largest part of their annual cycle outside the breeding grounds. Using light-level loggers (geolocators), we recorded the entire annual migratory cycle of the red-backed shrike Lanius collurio, a trans-equatorial Eurasian-African passerine migrant. We tested differences between autumn and spring migration for nine individuals. Duration of migration between breeding and winter sites was significantly longer in autumn (average 96 days) when compared with spring (63 days). This difference was explained by much longer staging periods during autumn (71 days) than spring (9 days). Between staging periods, the birds travelled faster during autumn (356 km d -1) than during spring (233 km d -1). All birds made a protracted stop (53 days) in Sahelian sub-Sahara on southbound migration. The birds performed a distinct loop migration (22 000 km) where spring distance, including a detour across the Arabian Peninsula, exceeded the autumn distance by 22 per cent. Geographical scatter between routes was particularly narrow in spring, with navigational convergence towards the crossing point from Africa to the Arabian Peninsula. Temporal variation between individuals was relatively constant, while different individuals tended to be consistently early or late at different departure/arrival occasions during the annual cycle. These results demonstrate the existence of fundamentally different spatio-temporal migration strategies used by the birds during autumn and spring migration, and that songbirds may rely on distinct staging areas for completion of their annual cycle, suggesting more sophisticated endogenous control mechanisms than merely clockand- compass guidance among terrestrial solitary migrants. After a century with metal-ringing, year-round tracking of long-distance migratory songbirds promises further insights into bird migration. © 2011 The Royal Society.


Akesson S.,Lund University | Klaassen R.,Lund University | Holmgren J.,Lund University | Fox J.W.,Natural Environment Research Council | And 2 more authors.
PLoS ONE | Year: 2012

The tracking of small avian migrants has only recently become possible by the use of small light-level geolocators, allowing the reconstruction of whole migration routes, as well as timing and speed of migration and identification of wintering areas. Such information is crucial for evaluating theories about migration strategies and pinpointing critical areas for migrants of potential conservation value. Here we report data about migration in the common swift, a highly aerial and long-distance migrating species for which only limited information based on ringing recoveries about migration routes and wintering areas is available. Six individuals were successfully tracked throughout a complete migration cycle from Sweden to Africa and back. The autumn migration followed a similar route in all individuals, with an initial southward movement through Europe followed by a more southwest-bound course through Western Sahara to Sub-Saharan stopovers, before a south-eastward approach to the final wintering areas in the Congo basin. After approximately six months at wintering sites, which shifted in three of the individuals, spring migration commenced in late April towards a restricted stopover area in West Africa in all but one individual that migrated directly towards north from the wintering area. The first part of spring migration involved a crossing of the Gulf of Guinea in those individuals that visited West Africa. Spring migration was generally wind assisted within Africa, while through Europe variable or head winds were encountered. The average detour at about 50% could be explained by the existence of key feeding sites and wind patterns. The common swift adopts a mixed fly-and-forage strategy, facilitated by its favourable aerodynamic design allowing for efficient use of fuel. This strategy allowed swifts to reach average migration speeds well above 300 km/day in spring, which is higher than possible for similar sized passerines. This study demonstrates that new technology may drastically change our views about migration routes and strategies in small birds, as well as showing the unexpected use of very limited geographical areas during migration that may have important consequences for conservation strategies for migrants. © 2012 Åkesson et al.

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