Cyclical Changes in Body Composition in the Annual Cycle and Migration of the Eared Grebe Podiceps nigricollis

1997 ◽  
Vol 28 (2) ◽  
pp. 132 ◽  
Author(s):  
Joseph R. Jehl
Keyword(s):  
Body Composition ◽  
Annual Cycle ◽  
Eared Grebe ◽  
Podiceps Nigricollis ◽  
And Migration

Eared Grebe (Podiceps nigricollis)

1999 ◽  
Author(s):  
S. A. Cullen ◽  
Joseph R. Jehl Jr. ◽  
Gary L. Nuechterlein
Keyword(s):  
Eared Grebe ◽  
Podiceps Nigricollis

scholarly journals Climate change relaxes the time constraints for late-born offspring in a long-distance migrant

2016 ◽  
Vol 283 (1839) ◽  
pp. 20161366 ◽  
Author(s):  
Barbara M. Tomotani ◽  
Phillip Gienapp ◽  
Domien G. M. Beersma ◽  
Marcel E. Visser
Keyword(s):  
Climate Change ◽  
Annual Cycle ◽  
Migratory Birds ◽  
Climate Change Impacts ◽  
Egg Laying ◽  
Time Constraints ◽  
Long Distance ◽  
Hatch Date ◽  
Breeding Bird ◽  
And Migration

Animals in seasonal environments need to fit their annual-cycle stages, such as moult and migration, in a tight schedule. Climate change affects the phenology of organisms and causes advancements in timing of these annual-cycle stages but not necessarily at the same rates. For migratory birds, this can lead to more severe or more relaxed time constraints in the time from fledging to migration, depending on the relative shifts of the different stages. We tested how a shift in hatch date, which has advanced due to climate change, impacts the organization of the birds' whole annual cycle. We experimentally advanced and delayed the hatch date of pied flycatcher chicks in the field and then measured the timing of their annual-cycle stages in a controlled laboratory environment. Hatch date affected the timing of moult and pre-migratory fattening, but not migration. Early-born birds hence had a longer time to fatten up than late-born ones; the latter reduced their interval between onset of fattening and migration to be able to migrate at the same time as the early-born birds. This difference in time constraints for early- and late-born individuals may explain why early-born offspring have a higher probability to recruit as a breeding bird. Climate change-associated advancements of avian egg-lay dates, which in turn advances hatch dates, can thus reduce the negative fitness consequences of reproducing late, thereby reducing the selection for early egg-laying migratory birds.

scholarly journals A full annual perspective on sex-biased migration timing in long-distance migratory birds

2019 ◽  
Vol 286 (1897) ◽  
pp. 20182821 ◽  
Author(s):  
Martins Briedis ◽  
Silke Bauer ◽  
Peter Adamík ◽  
José A. Alves ◽  
Joana S. Costa ◽  
...  
Keyword(s):  
Annual Cycle ◽  
Migratory Birds ◽  
Long Distance ◽  
Breeding Sites ◽  
Arrival Times ◽  
Migration Timing ◽  
Female Migration ◽  
Proximate Determinants ◽  
Carry Over ◽  
And Migration

In many taxa, the most common form of sex-biased migration timing is protandry—the earlier arrival of males at breeding areas. Here we test this concept across the annual cycle of long-distance migratory birds. Using more than 350 migration tracks of small-bodied trans-Saharan migrants, we quantify differences in male and female migration schedules and test for proximate determinants of sex-specific timing. In autumn, males started migration about 2 days earlier, but this difference did not carry over to arrival at the non-breeding sites. In spring, males on average departed from the African non-breeding sites about 3 days earlier and reached breeding sitesca4 days ahead of females. A cross-species comparison revealed large variation in the level of protandry and protogyny across the annual cycle. While we found tight links between individual timing of departure and arrival within each migration season, only for males the timing of spring migration was linked to the timing of previous autumn migration. In conclusion, our results demonstrate that protandry is not exclusively a reproductive strategy but rather occurs year-round and the two main proximate determinants for the magnitude of sex-biased arrival times in autumn and spring are sex-specific differences in departure timing and migration duration.

Eared Grebe (Podiceps nigricollis)

1999 ◽  
Author(s):  
S. A. Cullen ◽  
Joseph R. Jehl ◽  
Gary L. Nuechterlein
Keyword(s):  
Eared Grebe ◽  
Podiceps Nigricollis

scholarly journals Exploring Overlap of Feather Molting and Migration in Tundra Swans Using δ2H Analysis

2020 ◽  
Vol 7 (1) ◽  
pp. 58-66
Author(s):  
Nathan Wolf ◽  
T. Scott Smeltz ◽  
Jeffrey M. Welker ◽  
Matthew C. Rogers ◽  
Craig Ely
Keyword(s):  
Annual Cycle ◽  
Isotope Analysis ◽  
Satellite Tracking ◽  
Individual Variability ◽  
Relative Timing ◽  
Breeding Area ◽  
Migration Distance ◽  
Breast Feather ◽  
And Migration ◽  
Migrating Birds

AbstractDetermining the processes that shape the relative timing of energetically-costly events in the annual cycle of migrating birds is important to our understanding of avian phenology and ecology. We paired satellite tracking and hydrogen stable isotope analysis (δ2H) to examine the relative timing of two such events – migration and feather molting – in tundra swans from four breeding areas in Alaska, USA. Our results show a trend of increasing intra-individual variability in breast feather δ2H values with increasing migration distance, suggesting the overlap of breast feather molting and migration. However, when individual samples were pooled by breeding area, the δ2H values of breast and head feathers showed no trend with migration distance, presumably resulting from high levels of inter-individual variability in δ2H values within each breeding area. We explore potential reasons for this variability, propose potential mechanisms influencing feather δ2H values of tundra swans, and recommend further research into methods for exploring the temporal configuration of events in the annual cycle of migrating birds.

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