Reed warbler orientation: initiation of nocturnal migratory flights in relation to visibility of celestial cues at dusk

Åkesson, Susanne; Wålinder, Göran; Karlsson, Lennart; Ehnbom, Sophie

doi:10.1006/anbe.2000.1562

Cited by 80 publications

(71 citation statements)

References 35 publications

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“…If the expected wind support is low and not likely, birds wait for it for only some certain period of time (the "departure window") before departing anyway, even with headwinds (after the "giving-up time"). The occurrence of this mechanism was confirmed by the studies of Ckesson & Hedenström (2000) and Ckesson et al (2001), in which -despite a general tendency for migrants to depart with tailwinds and visible orientation cues -some cases of departure with unfavourable weather conditions were noted. This happened especially after birds encountered with a series of days affording.…”

Section: Introductionmentioning

confidence: 71%

Synchronisation of the Autumn Mass Migration of Passerines: a Case of RobinsErithacus rubecula

et al. 2005

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Section: Introductionmentioning

confidence: 71%

Synchronisation of the Autumn Mass Migration of Passerines: a Case of RobinsErithacus rubecula

et al. 2005

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“…In long-distance migrants, which in both seasons migrate during a shorter period and under more predictable weather conditions, variation in departure time is smaller (Hebrard 1971;Bolshakov and Bulyuk 2001;Å kesson et al 2001;Bolshakov and Chernetsov 2004;Bolshakov et al 2003a, b). Temporal distribution of captures of juvenile robins with different potential flight duration: a Fuel load insufficient to fly until Civil Twilight.…”

Section: Discussionmentioning

confidence: 95%

Timing of nocturnal autumn migratory departures in juvenile European robins (Erithacus rubecula) and endogenous and external factors

Bulyuk¹,

Tsvey²

2006

J Ornithol

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Many passerine medium distance nocturnal migrants take off from stopover sites not only at the beginning of the night, but also in the middle and at the end of the night. In this paper, we tested two explanations for this phenomenon: (1) that departure time is governed by fuel stores, and (2) that departure time is influenced by the weather. The relationship of temporal distribution of migratory nocturnal departures with body condition and weather factors was studied in juvenile European robins (Erithacus rubecula) during autumn migration. The study was done on the Courish Spit on the Baltic Sea in 1997-2003 by retrapping 74 ringed birds in high mist nets during nocturnal migratory departure. Departure time was not related to fuel stores at arrival and departure, stopover duration, fuel deposition rate or progress of the season. Nor did the local weather at departure influence departure time. A possible reason was a large variation in the behaviour of the birds. European robins which made 1-day stopovers arrived and departed during better weather conditions than birds that stopped over for longer periods. In the former cohort, a significant model with four predictors explained 55% of variation in departure time. It is assumed that weather at the night of departure and during the previous night influenced the time of take-offs in these birds. In robins which made long stopovers, departure time is probably governed by their individual endogenous circadian rhythms of activity, which are related to the environment in a complex way.

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“…The tailwinds associated with this synoptic weather pattern are particularly valuable to migrants crossing the Gulf, because they increase ground speed and reduce travel time and energy expenditure (36,38,52). Additionally, the clear skies of low-humidity nights provide good visibility for departure orientation; clear skies correlate with more departures and less orientation scatter (53). Ordinal day is likely important for predicting the arrival of over-water departures because synoptic weather systems favoring trans-Gulf flights (i.e., strong cold fronts moving into the GOM) become more common later in the fall (late September through October) (19,27,54).…”

Section: Discussionmentioning

confidence: 99%

Fat, weather, and date affect migratory songbirds’ departure decisions, routes, and time it takes to cross the Gulf of Mexico

Deppe

Ward

Bolus

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

166

210

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Approximately two thirds of migratory songbirds in eastern North America negotiate the Gulf of Mexico (GOM), where inclement weather coupled with no refueling or resting opportunities can be lethal. However, decisions made when navigating such features and their consequences remain largely unknown due to technological limitations of tracking small animals over large areas. We used automated radio telemetry to track three songbird species (Red-eyed Vireo, Swainson's Thrush, Wood Thrush) from coastal Alabama to the northern Yucatan Peninsula (YP) during fall migration. Detecting songbirds after crossing ∼1,000 km of open water allowed us to examine intrinsic (age, wing length, fat) and extrinsic (weather, date) variables shaping departure decisions, arrival at the YP, and crossing times. Large fat reserves and low humidity, indicative of beneficial synoptic weather patterns, favored southward departure across the Gulf. Individuals detected in the YP departed with large fat reserves and later in the fall with profitable winds, and flight durations (mean = 22.4 h) were positively related to wind profit. Age was not related to departure behavior, arrival, or travel time. However, vireos negotiated the GOM differently than thrushes, including different departure decisions, lower probability of detection in the YP, and longer crossing times. Defense of winter territories by thrushes but not vireos and species-specific foraging habits may explain the divergent migratory behaviors. Fat reserves appear extremely important to departure decisions and arrival in the YP. As habitat along the GOM is degraded, birds may be limited in their ability to acquire fat to cross the Gulf. migration | ecological barrier | Gulf of Mexico | songbirds | weather D uring migration, animals encounter ecological barriers, inhospitable environmental features that prevent or impede movement due to increased risk of mortality from starvation, predation, collision, and severe environmental conditions (e.g., weather for aerial migrants, aquatic temperature or chemical gradients for aquatic migrants) (1-5). Because barriers can have important consequences on survival and future reproductive success (6), animals have evolved behavioral, morphological, and/or physiological means to safely negotiate them (7-9). Barriers can include large geographic features (e.g., large water bodies, deserts, mountains), inhospitable land cover types (e.g., agricultural "deserts"), anthropogenic structures (e.g., tall buildings, towers, dams, weirs), and unfavorable weather and aquatic conditions (e.g., droughts, storms, strong temperature gradients), although the extent to which any of these functions as a barrier to migration varies (4,5,(10)(11)(12).Approximately two thirds of all songbird species and millions of individuals breeding in eastern Canada and the United States encounter the Gulf of Mexico (GOM) while migrating to tropical or subtropical wintering grounds in the Caribbean, Mexico, and Central and South America (13). Unfavorable weather conditions combine...

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Reed warbler orientation: initiation of nocturnal migratory flights in relation to visibility of celestial cues at dusk

Cited by 80 publications

References 35 publications

Synchronisation of the Autumn Mass Migration of Passerines: a Case of RobinsErithacus rubecula

Synchronisation of the Autumn Mass Migration of Passerines: a Case of RobinsErithacus rubecula

Timing of nocturnal autumn migratory departures in juvenile European robins (Erithacus rubecula) and endogenous and external factors

Fat, weather, and date affect migratory songbirds’ departure decisions, routes, and time it takes to cross the Gulf of Mexico

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