Cues, corticosterone and departure decisions in a partial migrant

Eikenaar, Cas; Ballstaedt, Elmar; Hessler, Sven; Klinner, Thomas; Fabbri, Muller; Schmaljohann, Heiko

doi:10.1016/j.ygcen.2018.01.023

Cited by 17 publications

(19 citation statements)

References 44 publications

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“…Indeed, when comparing migrating and resident Blackbirds at the same time and place, baseline innate immune function was negatively correlated with antioxidant capacity in migrating individuals, but not in the less energetically and physiologically challenged residents (Eikenaar et al 2018a). This suggests that migrants trade-off antioxidant defences with immune function during migration, while residents do not appear to make the same trade-off (Eikenaar et al 2018a).…”

Section: Oxidative Stressmentioning

confidence: 95%

“…Interestingly, in the same system, migrating Blackbirds had lower parameters of innate immune function compared to residents (Eikenaar and Hegemann 2016). As immune function and immune responses can cause oxidative stress (von Schantz et al 1999;Costantini and Moller 2009), this led to the hypothesis that migrants may need to down-regulate immune function during their energy-demanding migration when oxidative stress is highest (Eikenaar et al 2018a). Indeed, when comparing migrating and resident Blackbirds at the same time and place, baseline innate immune function was negatively correlated with antioxidant capacity in migrating individuals, but not in the less energetically and physiologically challenged residents (Eikenaar et al 2018a).…”

Section: Oxidative Stressmentioning

confidence: 99%

“…As immune function and immune responses can cause oxidative stress (von Schantz et al 1999;Costantini and Moller 2009), this led to the hypothesis that migrants may need to down-regulate immune function during their energy-demanding migration when oxidative stress is highest (Eikenaar et al 2018a). Indeed, when comparing migrating and resident Blackbirds at the same time and place, baseline innate immune function was negatively correlated with antioxidant capacity in migrating individuals, but not in the less energetically and physiologically challenged residents (Eikenaar et al 2018a). This suggests that migrants trade-off antioxidant defences with immune function during migration, while residents do not appear to make the same trade-off (Eikenaar et al 2018a).…”

Section: Oxidative Stressmentioning

confidence: 99%

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A physiological perspective on the ecology and evolution of partial migration

2019

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Billions of animals migrate between breeding and non-breeding areas worldwide. Partial migration, where both migrants and residents coexist within a population, occurs in most animal taxa, including fish, insects, birds and mammals. Partial migration has been hypothesised to be the most common form of migration and to be an evolutionary precursor to full migration. Despite extensive theoretical models about partial migration and its potential to provide insight into the ecology and evolution of migration, the physiological mechanisms that shape partial migration remain poorly understood. Here, we review current knowledge on how physiological processes mediate the causes and consequences of avian partial migration, and how they may help us understand why some individuals migrate and others remain resident. When information from birds is missing, we highlight examples from other taxa. In particular, we focus on temperature regulation, metabolic rate, immune function, oxidative stress, telomeres, and neuroendocrine and endocrine systems. We argue that these traits provide physiological pathways that regulate the ecological and behavioural causes and/or consequences of partial migration, and may provide insight into the mechanistic basis of wintering decisions. They may, thus, also help us to explain why individuals switch strategies among winters. We also highlight current gaps in our knowledge and suggest promising future research opportunities. A deeper understanding of the physiological mechanisms mediating the causes and consequences of partial migration will not only provide novel insights into the ecology and evolution of migration in general, but will also be vital to precisely modelling population trends and predicting range shifts under global change. Keywords Ecophysiology • Ecoimmunology • Hormones • Metabolism • Movement ecology • Avian life history Zusammenfassung Weltweit ziehen Milliarden von Vögeln zwischen Brut-und Überwinterungsgebieten. Eine der häufigsten Zugformen ist Teilzug. Bei Teilzug gibt es innerhalb einer Population sowohl Zugvögel als auch Standvögel. Diese Form des Zuges gibt es in fast allen Tiergruppen, von Fischen über Insekten und Vögel bis hin zu Säugetieren. Teilzug ist möglicherwiese die evolutionäre Frühform von vollständigem Zug. Obwohl es viele theoretische Modelle über Teilzug gibt und Teilzug das Potential hat uns viele Einblicke in die Ökologie und Evolution von Zugverhalten zu geben, sind die physiologischen Mechanismen die Teilzug regulieren weitgehend unbekannt. In dieser Literaturübersicht fassen wir das derzeitige Wissen wie physiologische Prozesse die Ursachen und Folgen von Teilzug regulieren zusammen. Wir zeigen auf wie ein Verständnis der physiologischen Prozesse uns dabei helfen kann zu verstehen warum manche Individuen ziehen und andere Standvögel sind. Unsere Literaturübersicht fokussiert sich auf Wissen an Vögeln, aber wenn solches Wissen nicht vorhanden ist, greifen wir auf Beispiele von anderen Tiergruppen zurück. Wir fokussieren uns auf die folgenden physiol...

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Section: Oxidative Stressmentioning

confidence: 95%

Section: Oxidative Stressmentioning

confidence: 99%

Section: Oxidative Stressmentioning

confidence: 99%

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A physiological perspective on the ecology and evolution of partial migration

2019

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“…Yet another possibility is that extended activity is a by‐product of hormonal changes, which regulate preparatory activities at seasonal and diel scales (Wingfield 2008, Ramenofsky and Wingfield 2017). Corticosterone is a likely candidate for such a hormone, as higher levels of plasma corticosterone are associated with a higher probability of departure, elevated nocturnal restlessness and earlier departure time in migratory songbirds (Lõhmus et al 2003, Eikenaar et al 2014, 2017, 2018a, 2018b, 2020). Finally, given the correlational nature of the data, we cannot rule out that changes in diel schedules increase the probability of departure that evening, rather than vice versa.…”

Section: Discussionmentioning

confidence: 99%

Evening locomotor activity during stopover differs on pre‐departure and departure days in free‐living songbirds

Morbey

Beauchamp

Bonner

et al. 2020

Journal of Avian Biology

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The length of time songbirds remain at a migratory stopover site is likely regulated by a daily stay/go decision informed by fat stores and weather conditions, but the finerscale timing of this decision and associated pre-departure behaviours are still poorly understood. Using automated radiotelemetry of free-living songbirds captured at a migratory stopover site in spring, we tested whether individuals change their locomotor activity near sunset on their migratory departure day compared to their non-departure days. To do so, we extracted precise transition times between diurnal activity and nocturnal inactivity, which always precedes departure, using changepoint analysis of radio transmission signal strength. Among four warbler species, individuals extended diurnal activity by 8-19 min towards sunset on their departure day. In three species, this extension was significant. In contrast, white-throated sparrows significantly shortened diurnal activity on their departure day by 13 min, also towards sunset. This is the first study to detect and quantify a change in locomotor activity schedule on departure versus non-departure days in free-living songbirds, and is consistent with the hypothesis that birds engage in pre-departure preparatory behaviours near sunset.

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“…Body mass (±0.1 g), using an electronic scale, and the QMR fat mass (±0.01 g; hereafter: "absolute fuel load"), using the EchoMRI™ (EchoMRI Body Composition Analyser E26-262-BH, Zinsser Analytic GmbH, Frankfurt am Main, Germany; for more details on functionality, software settings, validation and accuracy see Kelsey & Bairlein [71], Kelsey et al [72] and Additional le chapter 2), were measured for each bird on the day of rst capture. This is considered to be the day of arrival [35], as most ringed blackbirds only stay on Helgoland for one or two days [73]; but median of four to ve days in radio-telemetered blackbirds [35,74]. Furthermore, it can be assumed that birds are most mobile on the rst day after arrival and therefore the probability of capture is highest [75,76,77].…”

Section: Methodsmentioning

confidence: 99%

Days to Visit an Offshore Island: Effect of Weather Conditions on Arrival Fuel Load and Potential Flight Range for Common Blackbirds Turdus Merula Migrating Over the North Sea

Kelsey

Hüppop

Bairlein

2021

Preprint

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Background: Crossing open water instead of following the coast(line) is one way for landbirds to continue migration. However, depending on prevailing weather and the birds’ physiological condition, it is also a risky choice. To date, the question remains as to which interplay between environmental conditions and physiological condition force landbirds to stop on remote islands. We hypothesise that unfavourable winds would affect lean birds with low energy resources, while poor visibility would affect all birds regardless of their fuel load. Methods: To test this hypothesis, we used data of 1312 Common Blackbirds Turdus merula, caught while stopping over on Helgoland during autumn and spring migration. Arrival fuel load was measured using quantitative magnetic resonance technology. Weather parameters (wind and relative humidity as a proxy for visibility) were interpolated for the night before arrival. Further, we calculated whether caught individuals would have managed to successfully cross the North Sea instead of landing on Helgoland, depending on wind conditions. Results: Both wind and relative humidity the night before arrival were correlated with arrival fuel load. After nights with strong headwinds, birds caught the following day were mostly lean, most of which would not have managed to cross the sea if they had not stopped on Helgoland. On the other hand, fat birds that could have successfully travelled on were caught mainly after nights with high relative humidity (≥ 80%). Furthermore, the rate of presumably successful flights was lower due to wind: although only 9% of all blackbirds captured on Helgoland had insufficient fuel loads to allow safe onward migration in still air, real wind conditions would have prevented 30% of birds from successfully crossing the sea during autumn and 21% during spring migration. Conclusions: We were able to decipher how physiological condition, wind and relative humidity force blackbirds to stop on a remote island. Adverse winds tend to affect lean birds with low energy resources, while poor visibility affects all birds, regardless of whether the arrival fuel load was sufficient for onward flight. Our findings will help to understand different migratory strategies and explain further questions like migration timing.

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Cues, corticosterone and departure decisions in a partial migrant

Cited by 17 publications

References 44 publications

A physiological perspective on the ecology and evolution of partial migration

A physiological perspective on the ecology and evolution of partial migration

Evening locomotor activity during stopover differs on pre‐departure and departure days in free‐living songbirds

Days to Visit an Offshore Island: Effect of Weather Conditions on Arrival Fuel Load and Potential Flight Range for Common Blackbirds Turdus Merula Migrating Over the North Sea

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