Developing a Stopover-CORT hypothesis: Corticosterone predicts body composition and refueling rate in Gray Catbirds during migratory stopover

DeSimone, Joely G.; Ramirez, Mariamar Gutierrez; Elowe, Cory R.; Griego, Michael S.; Breuner, Creagh W.; Gerson, Alexander R.

doi:10.1016/j.yhbeh.2020.104776

Cited by 10 publications

(6 citation statements)

References 93 publications

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“…In addition to fuelling, it is widely believed that stopovers serve as periods during which migrants rest and/or recover from the preceding migratory endurance flight (e.g. Biebach, Friedrich & Heine, 1986; Latta & Brown, 1999; Dunn, 2000; Salewski & Schaub, 2007; Taylor et al ., 2011; Schofield et al ., 2018b; Holberton et al ., 2019; DeSimone et al ., 2020). That an organism needs to rest and recover physiologically after a period of endurance exercise seems a plausible explanation for stopping over.…”

Section: The Multiple Functions Of Stopovermentioning

confidence: 99%

Understanding the ecological and evolutionary function of stopover in migrating birds

2022

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Global movement patterns of migratory birds illustrate their fascinating physical and physiological abilities to cross continents and oceans. During their voyages, most birds land multiple times to make so-called 'stopovers'. Our current knowledge on the functions of stopover is mainly based on the proximate study of departure decisions. However, such studies are insufficient to gauge fully the ecological and evolutionary functions of stopover. If we study how a focal trait, e.g. changes in energy stores, affects the decision to depart from a stopover without considering the trait(s) that actually caused the bird to land, e.g. unfavourable environmental conditions for flight, we misinterpret the function of the stopover. It is thus important to realise and acknowledge that stopovers have many different functions, and that not every migrant has the same (set of) reasons to stop-over. Additionally, we may obtain contradictory results because the significance of different traits to a migrant is context dependent. For instance, late spring migrants may be more prone to risktaking and depart from a stopover with lower energy stores than early spring migrants. Thus, we neglect that departure decisions are subject to selection to minimise immediate (mortality risk) and/or delayed (low future reproductive output) fitness costs. To alleviate these issues, we first define stopover as an interruption of migratory endurance flight to minimise immediate and/or delayed fitness costs. Second, we review all probable functions of stopover, which include accumulating energy, various forms of physiological recovery and avoiding adverse environmental conditions for flight, and list potential other functions that are less well studied, such as minimising predation, recovery from physical exhaustion and spatiotemporal adjustments to migration. Third, derived from these aspects, we argue for a paradigm shift in stopover ecology research. This includes focusing on why an individual interrupts its migratory flight, which is more likely to identify the individualspecific function(s) of the stopover correctly than departure-decision studies. Moreover, we highlight that the selective forces acting on stopover decisions are context dependent and are expected to differ between, e.g. K−/r-selected species, the sexes and migration strategies. For example, all else being equal, r-selected species (low survival rate, high reproductive rate) should have a stronger urge to continue the migratory endurance flight or resume migration from a stopover because the potential increase in immediate fitness costs suffered from a flight is offset by the expected higher reproductive success in the subsequent breeding season. Finally, we propose to focus less on proximate mechanisms controlling landing and departure decisions, and more on ultimate mechanisms to identify the selective forces shaping stopover decisions. Our ideas are not limited to birds but can be applied to any migratory species. Our revised definition of stopover and the proposed paradigm shi...

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Section: The Multiple Functions Of Stopovermentioning

confidence: 99%

Understanding the ecological and evolutionary function of stopover in migrating birds

2022

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“…3 School of Food and Agriculture, University of Maine, Orono, ME, USA. 4 Department of Environmental Science Policy and Management, University of California, Berkeley, Berkeley, CA, USA. 5 School of Mathematical Sciences, University of KwaZulu-Natal, Durban, South Africa.…”

Section: Supplementary Informationmentioning

confidence: 99%

“…Many bird species spend a significant part of their annual cycle migrating [ 1 , 2 ], flying thousands of kilometers between favorable breeding- and non-breeding locations while coping with variable flight conditions and foraging habitats en route [ 3 ]. Long-distance migration is physiologically and energetically demanding and involves morphological and physiological adjustments, such as shifts in flight muscles, body fat, and overall body mass [ 4 ], as well as downregulation of digestion [ 5 ] or immune response [ 6 ]. The physiological adjustments associated with migration could be linked to the microbiota composition found in an individual’s gut, known to play an important role in processes like digestion and nutrient uptake [ 7 ], immune system function [ 8 ] and protection against pathogenic infections [ 9 ].…”

Section: Introductionmentioning

confidence: 99%

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Linking migration and microbiota at a major stopover site in a long-distance avian migrant

et al. 2022

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Migration is one of the most physical and energetically demanding periods in an individual bird’s life. The composition of the bird’s gut or cloacal microbiota can temporarily change during migration, likely due to differences in diets, habitats and other environmental conditions experienced en route. However, how physiological condition, migratory patterns, and other drivers interact to affect microbiota composition of migratory birds is still unclear. We sampled the cloacal bacterial microbiota of a long-distance migrant, the steppe buzzard (Buteo buteo vulpinus), at an important spring stopover bottleneck in Eilat, Israel, after crossing the ca. 1800 km Sahara Desert. We examined whether diversity and composition of the cloacal microbiota varied with body condition, sex, movement patterns (i.e., arrival time and migration distance), and survival. Early arrival to Eilat was associated with better body condition, longer post-Eilat spring migration distance, higher microbial α-diversity, and differences in microbiota composition. Specifically, early arrivals had higher abundance of the phylum Synergistota and five genera, including Jonquetella and Peptococcus, whereas the phylum Proteobacteria and genus Escherichia-Shigella (as well as three other genera) were more abundant in later arrivals. While the differences in α-diversity and Escherichia-Shigella seem to be mainly driven by body condition, other compositional differences associated with arrival date could be indicators of longer migratory journeys (e.g., pre-fueling at wintering grounds or stopover habitats along the way) or migratory performance. No significant differences were found between the microbiota of surviving and non-surviving individuals. Overall, our results indicate that variation in steppe buzzard microbiota is linked to variation in migratory patterns (i.e., capture/arrival date) and body condition, highlighting the importance of sampling the microbiota of GPS-tracked individuals on multiple occasions along their migration routes to gain a more detailed understanding of the links between migration, microbiota, and health in birds.

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“…Risk responsiveness diminishes when animals face energy shortages because low glucose levels inhibit HPA axis activity (Kirschbaum et al, 1997), likely blunting selection for safer habitats after encountering predators. At the same time, low energy availability also encourages selection for foraging habitat since reductions in energy storage —adipose tissue and circulating triglycerides — reduces peripheral signals of satiety (Dallman et al, 1993) and keeps baseline glucocorticoids at higher levels that stimulate feeding (DeSimone et al, 2020). In the long term, food limitation leads to familiar seasonal habitat selection patterns where maintaining body condition is prioritized over survival.…”

Section: Introductionmentioning

confidence: 99%

Life history trade-offs in glucocorticoid-mediated habitat selection

Newediuk

Mastromonaco

Wal

2022

Preprint

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Glucocorticoid production is often indicative of internal state that underpins movement and resulting habitat selection. Habitat selection is adaptive behaviour, but habitats where animals exhibit atypical glucocorticoid production are often associated with low fitness. Discrepancies between poor fitness outcomes and purported adaptive behaviour have contributed to a lack of consensus about the ecological and evolutionary implications of glucocorticoid production.We aim to demonstrate the adaptive ecological and evolutionary roles of glucocorticoids by integrating stress physiology with habitat selection theory.First, we show how habitat selection theory can benefit from a mechanistic understanding of the relationships between stressors, internal state, and habitat selection. We show that glucocorticoids drive everything from short-term locomotion to large-scale movements. In turn, these movements produce familiar patterns of adaptive habitat selection like habitat specialization and migration. Populations arrive at these evolutionarily stable habitat selection strategies by responding to stressors like predation and food availability. To quantify responses to stressors, we show how to parameterize glucocorticoid data in habitat selection models. Modelling the ecological and evolutionary patterns that make habitat selection adaptive also help clarify relationships between glucocorticoids, stress, and fitness.Our approach delivers a practical framework for testing existing hypotheses about habitat selection and stress physiology. Our framework can also be applied to new questions that integrate both, with the potential to understand adaptations of populations to their environments, and implications of stressors and habitat selection for ecosystem functioning.

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Developing a Stopover-CORT hypothesis: Corticosterone predicts body composition and refueling rate in Gray Catbirds during migratory stopover

Cited by 10 publications

References 93 publications

Understanding the ecological and evolutionary function of stopover in migrating birds

Understanding the ecological and evolutionary function of stopover in migrating birds

Linking migration and microbiota at a major stopover site in a long-distance avian migrant

Life history trade-offs in glucocorticoid-mediated habitat selection

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