Ecological factors influence timing of departures in nocturnally migrating songbirds at Falsterbo, Sweden

Sjöberg, Sissel; Alerstam, Thomas; Åkesson, Susanne; Muheim, Rachel

doi:10.1016/j.anbehav.2017.03.007

Cited by 32 publications

(44 citation statements)

References 40 publications

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“…Late departures were found in leucorhoa Wheatears flying towards a nearby coast and thus initially circumventing the extended sea barrier (Figure ). This matches the results of comparable radiotelemetry studies (Schmaljohann & Naef‐Daenzer, ; Sjöberg et al., ; Smolinsky et al., ), but see (Sjöberg et al., ). Late departures towards the seasonally appropriate migration direction were found among oenanthe Wheatears only (Figure ).…”

Section: Discussionsupporting

confidence: 89%

“…Further, at the end of civil twilight, the brightest stars get visible. The observed pattern in this study together with others (Sjöberg et al., ) suggests that migratory songbirds depend on input of either or both cues before departure. This dependence could potentially prevent the innate (subspecies‐specific) difference from its manifestation under free‐flying conditions and hence explain its apparent absence in the present study (Figure ).…”

Section: Discussionsupporting

confidence: 87%

“…Nocturnal migrants use celestial cues, for example polarized light patterns and stars, to calibrate their different compass systems and for navigation at night (reviewed in Chernetsov, ). Their temporal occurrence during evening twilight has been hypothesized to affect nocturnal departure timing (Åkesson, Alerstam, & Hedenström, ) and/or provide a temporal threshold for earliest nocturnal departures (Sjöberg et al., ). This is supported by our study, as earliest departures occurred at sun elevations of c .…”

Section: Discussionmentioning

confidence: 99%

“…Part of this variation seems to be explained by intrinsic factors (fuel stores) and extrinsic factors (wind; Müller et al, 2016), which are known to act as cues for day-to-day departure decisions in migrants (Bolus et al, 2017;Deppe et al, 2015;Schmaljohann & Eikenaar, 2017;Shamoun-Baranes, Liechti, & Vansteelant, 2017;Smolinsky, Diehl, Radzio, Delaney, & Moore, 2013). Several studies revealed that birds carrying large fuel stores and experiencing favourable winds depart early at night, whereas birds migrating with little fuel and under unfavourable winds show considerable variation in their nocturnal departure timing (Eikenaar, Müller, Kämpfer, & Schmaljohann, 2016;Schmaljohann & Naef-Daenzer, 2011;Sjöberg, Alerstam, Åkesson, & Muheim, 2017;Sjöberg et al, 2015;Smolinsky et al, 2013), but this pattern is not ubiquitous (Bolshakov et al, 2007;Bulyuk, 2012;Bulyuk & Tsvey, 2006). There is also suggestive evidence that nocturnal departure timing advances with a decrease in night length (Eikenaar et al, 2016;Schmaljohann et al, 2013;Sjöberg et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

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Nocturnal departure timing in songbirds facing distinct migratory challenges

Fabbri

Eikenaar

Crysler

et al. 2018

Journal of Animal Ecology

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Most migratory songbirds travel between their breeding areas and wintering grounds through a series of nocturnal flights. The timing of their departures defines the potential flight duration and thus the distance covered during a migratory night. Yet, migratory songbirds show substantial variation in their nocturnal departure timing. With this study, we aim to assess whether the respective challenges of the migration route, namely its distance and nature, help to explain this variation. At a stopover site, we caught Northern Wheatears (Oenanthe oenanthe) of two subspecies that differ in distance and nature of their onward migration route in spring, but not in autumn. We determined the start of their nocturnal migratory restlessness during short-term captivity, and radiotracked their nocturnal departure timing after release in both migration seasons. Northern Wheatears started their nocturnal migratory restlessness earlier when facing a long remaining migration distance and an extended sea barrier in spring. Individual departure directions generally affected the nocturnal departure timing with early departures being directed towards the respective migratory destination. In spring, this pattern was predominantly found in birds carrying relatively large fuel stores, but was absent in lean birds. At the same time, birds facing a short remaining migration distance and no extended sea barrier strongly reacted to relatively large fuel stores by an early start of nocturnal migratory behaviour (migratory restlessness and departure timing), whereas this reaction was not found in birds facing a long remaining migration distance and sea barrier. These results suggest that the basic diel schedule of birds' migratory activity is adapted to the onward migration route. Further, they suggest that birds adjust their behavioural response, that is start of nocturnal migratory behaviour, to fuel stores in relation to their impending migratory challenges. This is a substantial step in understanding variation of nocturnal departure timing and its adjustments in migratory songbirds. Further, it emphasizes the importance of interpreting birds' nocturnal migratory behaviour in the respective ecological context.

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Section: Discussionsupporting

confidence: 89%

Section: Discussionsupporting

confidence: 87%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Nocturnal departure timing in songbirds facing distinct migratory challenges

Fabbri

Eikenaar

Crysler

et al. 2018

Journal of Animal Ecology

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“…We used an automated radio-telemetry system at Falsterbo peninsula to determine stopover duration and stopover behaviour, and coded radio-tags were attached to all birds by gluing them to the back of the birds after cutting some feathers on the bird’s back (Sjöberg et al 2017). The five smaller species were tagged with NTQBW-2 Coded Tags (LOTEK, weight 0.3 g).…”

Section: Methodsmentioning

confidence: 99%

Immune function and blood parasite infections impact stopover ecology in passerine birds

et al. 2018

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Stopovers play a crucial role for the success of migrating animals and are key to optimal migration theory. Variation in refuelling rates, stopover duration and departure decisions among individuals has been related to several external factors. The physiological mechanisms shaping stopover ecology are, however, less well understood. Here, we explore how immune function and blood parasite infections relate to several aspects of stopover behaviour in autumn migrating short- and long-distance migrating songbirds. We blood sampled individuals of six species and used an automated radio-telemetry system in the stopover area to subsequently quantify stopover duration, ‘bush-level’ activity patterns (~ 0.1–30 m), landscape movements (~ 30–6000 m), departure direction and departure time. We show that complement activity, the acute phase protein haptoglobin and blood parasite infections were related to prolonged stopover duration. Complement activity (i.e., lysis) and total immunoglobulins were negatively correlated with bush-level activity patterns. The differences partly depended on whether birds were long-distance or short-distance migrants. Birds infected with avian malaria-like parasites showed longer landscape movements during the stopover than uninfected individuals, and birds with double blood parasite infections departed more than 2.5 h later after sunset/sunrise suggesting shorter flight bouts. We conclude that variation in baseline immune function and blood parasite infection status affects stopover ecology and helps explain individual variation in stopover behaviour. These differences affect overall migration speed, and thus can have significant impact on migration success and induce carry-over effects on other annual-cycle stages. Immune function and blood parasites should, therefore, be considered as important factors when applying optimal migration theory.Electronic supplementary materialThe online version of this article (10.1007/s00442-018-4291-3) contains supplementary material, which is available to authorized users.

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The urge to breed early: Similar responses to environmental conditions in short‐ and long‐distance migrants during spring migration

Rüppel

Hüppop

Schmaljohann

et al. 2023

Ecology and Evolution

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Birds migrating different distances experience different temporal, energetic, physiological, and physical constraints throughout migration, which is reflected in their migration strategy. Consequently, we predict different behavioral decisions to similar environmental cues between short-and long-distance migrants, which has been documented for autumn migration. Here, we focus on the question whether tradeoff decisions regarding departure, routing, and landing when alternating between migratory endurance flights and stopovers also differ during spring migration. As early arrivals at the breeding grounds should be ultimately favored regardless of migration distance, selection may favor more similar behavioral decisions in spring than in autumn. We radio-tagged short-and long-distance migratory songbirds at stopover sites along the German North Sea coast during spring and automatically tracked their migratory behavior using a large-scale network of receiver stations. Once departed, birds could either cross the sea or detour along the coast. We corrected for spatially biased detection data, using a hierarchical multistate model to assess how birds respond to variation in environmental conditions in their day-to-day departure decisions and route selection. The day-to-day departure probability was higher in long-distance migrants independently of the routing decision. Irrespective of migration distance, all species more likely departed under light winds and rainless conditions, while the influence of air pressure change and relative humidity was species-specific. By accounting for detection probabilities, we estimated that about half of all individuals of each species crossed the sea but did not find differences between short-and longdistance migrants. Offshore flights were more likely when winds blew offshore and began earlier within the night compared with onshore flights. Our results suggest that selection more similarly affects birds of different migration distances in spring than in autumn. These findings put the focus toward how ultimate mechanisms may shape departure and routing decisions differently between migration seasons.

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Ecological factors influence timing of departures in nocturnally migrating songbirds at Falsterbo, Sweden

Cited by 32 publications

References 40 publications

Nocturnal departure timing in songbirds facing distinct migratory challenges

Nocturnal departure timing in songbirds facing distinct migratory challenges

Immune function and blood parasite infections impact stopover ecology in passerine birds

The urge to breed early: Similar responses to environmental conditions in short‐ and long‐distance migrants during spring migration

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