Cold tolerance, and not earlier arrival on breeding grounds, explains why males winter further north in an Arctic‐breeding songbird

Macdonald, Christie A.; McKinnon, Emily A.; Gilchrist, H. Grant; Love, Oliver P.

doi:10.1111/jav.00689

Cited by 30 publications

(26 citation statements)

References 42 publications

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“…A2-A3). This provides support to a similar, but non-significant, trend reported in snow buntings by Macdonald et al (2015), suggesting that sex is more important than age in influencing energy management in this species. This difference in energy levels across sex and age classes could potentially be related to social status (Ficken et al 1990, Ekman andLilliendahl 1993) as in passerines dominant individuals are typically leaner than subordinates because their status provides priority over resources (Clark and Ekman 1995).…”

Section: The Importance Of Sex and Age In Winter Energy Levelssupporting

confidence: 82%

Flexible response to short‐term weather in a cold‐adapted songbird

Laplante

McKinnon

Love

et al. 2019

Journal of Avian Biology

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To improve survival during winter, temperate species use a variety of behavioural and physiological adaptations. Among songbirds, the maintenance of lipid reserves is a widely‐used strategy to cope with the severity of winter; however, little is known regarding how multiple synchronously acting environmental mechanisms work together to drive these effects. In a context where temperate winter conditions are becoming more variable, it is important to widen our understanding regarding the flexible adaptations that may allow wintering species to adjust to projected climate change. Using a long‐term dataset collected across multiple wintering populations (7 years; 8 locations), we analyzed the effects of daily variation in weather (e.g. temperature, snowfall) on the variation in energy reserves (i.e. fat stores) of wintering snow buntings Plectrophenax nivalis. Our results support the prediction that birds carry more reserves to increase the safety margin against starvation when conditions are energy‐demanding and access to food is unpredictable (i.e. colder, snowier conditions). Birds responded to daily changes in weather by increasing their reserves as conditions deteriorated, with maximal temperatures and snow depth being the most important predictors of fattening decisions. We also found that females consistently exhibited higher fat reserves than males relative to their body size, suggesting that differential physiological adaptations among sexes or social dominance may play an additional role in explaining variation in energy reserves across individuals in this species. Overall, our findings increase knowledge on phenotypic adjustments used by species wintering in temperate zones to match variation in their environment.

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Section: The Importance Of Sex and Age In Winter Energy Levelssupporting

confidence: 82%

Flexible response to short‐term weather in a cold‐adapted songbird

Laplante

McKinnon

Love

et al. 2019

Journal of Avian Biology

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“…Based on geolocation, banding and observational data from 2007 to 2013, we know the majority of males arrive on East Bay Island before females (Macdonald et al. , ), supporting the idea that the earliest arriving females have the broadest choice of breeding partners (Guindre‐Parker et al. ,b).…”

Section: Methodsmentioning

confidence: 57%

“…data), especially for females (Macdonald et al. , ). Based on geolocation, banding and observational data from 2007 to 2013, we know the majority of males arrive on East Bay Island before females (Macdonald et al.…”

Section: Methodsmentioning

confidence: 98%

The Oxidative Cost of Acoustic Signals: Examining Steroid Versus Aerobic Activity Hypotheses in a Wild Bird

et al. 2015

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Vertebrate vocalizations are widespread secondary sexual signals used for mate attraction and territory defence, and variation in signal quality is often condition dependent and impacts reproductive outcomes. Although vocal signal performance is known to reflect various aspects of male quality, few studies have examined the underlying mechanisms mediating its costs and hence its honesty. Using a population of Arctic-breeding snow buntings (Plectrophenax nivalis), we compared the 'Oxidation Handicap Hypothesis', which predicts that testosterone-induced increases in oxidative stress provide a direct mechanistic basis for ensuring the honesty of many secondary sexual signals, to the 'Aerobic Activity Hypothesis, which predicts that it is the aerobic activity involved with signal production (i.e. vocal performance or defending a large territory) and not testosterone directly that links signal quality and oxidative stress. Males singing at faster rates had higher levels of both reactive oxygen metabolites and non-enzymatic antioxidant capacity in the plasma (i.e. without an increase in overall oxidative stress), enabling certain males to produce high-quality signals while also mitigating the costs of an associated increase in oxidative stress. However, these results were completely independent of plasma testosterone levels, supporting the role of aerobic performance in directly affecting oxidative stress. Although song performance was not linked to reproductive parameters in our data set, our research is the first to test these competing hypotheses in a behavioural trait and results suggest that oxidative stress may be an underlying physiological cost preventing low-quality individuals from producing high-quality signals.

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“…The best‐supported model of migration distance included a body size–colony size interaction. Partial migration patterns have previously been associated with individual differences in social status (e.g., Cristol, Baker, & Carbone, ; Terrill, ), variation in thermal tolerance with body size (e.g., Belthoff & Gauthreaux, ; Chapman et al., ; Macdonald, McKinnon, Gilchrist, & Love, ), or differential fitness benefits to males of early arrival at the breeding site (e.g., Myers, ; Pérez et al., ). The majority of our top models for migratory behavior contained colony size in combination or interaction with one or more individual characteristics (sex, body size, and/or condition), indicating that the influence of individual characteristics on migration propensity and distance is mediated by density‐dependent competition.…”

Section: Discussionmentioning

confidence: 99%

Influence of density‐dependent competition on foraging and migratory behavior of a subtropical colonial seabird

Lamb

Satgé

Jodice

2017

Ecology and Evolution

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Density‐dependent competition for food resources influences both foraging ecology and reproduction in a variety of animals. The relationship between colony size, local prey depletion, and reproductive output in colonial central‐place foragers has been extensively studied in seabirds; however, most studies have focused on effects of intraspecific competition during the breeding season, while little is known about whether density‐dependent resource depletion influences individual migratory behavior outside the breeding season. Using breeding colony size as a surrogate for intraspecific resource competition, we tested for effects of colony size on breeding home range, nestling health, and migratory patterns of a nearshore colonial seabird, the brown pelican (Pelecanus occidentalis), originating from seven breeding colonies of varying sizes in the subtropical northern Gulf of Mexico. We found evidence for density‐dependent effects on foraging behavior during the breeding season, as individual foraging areas increased linearly with the number of breeding pairs per colony. Contrary to our predictions, however, nestlings from more numerous colonies with larger foraging ranges did not experience either decreased condition or increased stress. During nonbreeding, individuals from larger colonies were more likely to migrate, and traveled longer distances, than individuals from smaller colonies, indicating that the influence of density‐dependent effects on distribution persists into the nonbreeding period. We also found significant effects of individual physical condition, particularly body size, on migratory behavior, which in combination with colony size suggesting that dominant individuals remain closer to breeding sites during winter. We conclude that density‐dependent competition may be an important driver of both the extent of foraging ranges and the degree of migration exhibited by brown pelicans. However, the effects of density‐dependent competition on breeding success and population regulation remain uncertain in this system.

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Cold tolerance, and not earlier arrival on breeding grounds, explains why males winter further north in an Arctic‐breeding songbird

Cited by 30 publications

References 42 publications

Flexible response to short‐term weather in a cold‐adapted songbird

Flexible response to short‐term weather in a cold‐adapted songbird

The Oxidative Cost of Acoustic Signals: Examining Steroid Versus Aerobic Activity Hypotheses in a Wild Bird

Influence of density‐dependent competition on foraging and migratory behavior of a subtropical colonial seabird

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