Hot days are associated with short-term adrenocortical responses in a southern African arid-zone passerine bird

Moagi, Lesedi L.; Bourne, Amanda R.; Cunningham, Susan J.; Jansen, Raymond; Ngcamphalala, Celiwe A.; Ganswindt, André; Ridley, Amanda R.; McKechnie, Andrew E.

doi:10.1242/jeb.242535

Cited by 24 publications

(22 citation statements)

References 54 publications

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“…To avoid hyperthermia, birds make behavioral (e.g., reducing activity, heat dissipation behaviors) and physiological (e.g., increasing evaporative water loss) adjustments to increase heat loss ( 15 , 16 ), which can bring about dehydration and a loss of energy reserves ( 16 , 17 ). Increased body temperatures result in higher resting metabolic rates, reduced enzyme performance, and increased production of heat shock proteins and glucocorticoid stress hormones ( 18 – 20 ). These physiological changes may affect the development and growth of offspring, with potential fitness consequences into adulthood.…”

mentioning

confidence: 99%

Hot and dry conditions predict shorter nestling telomeres in an endangered songbird: Implications for population persistence

Eastwood

Connallon

Delhey

et al. 2022

Proc. Natl. Acad. Sci. U.S.A.

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Climate warming is increasingly exposing wildlife to sublethal high temperatures, which may lead to chronic impacts and reduced fitness. Telomere length (TL) may link heat exposure to fitness, particularly at early-life stages, because developing organisms are especially vulnerable to adverse conditions, adversity can shorten telomeres, and TL predicts fitness. Here, we quantify how climatic and environmental conditions during early life are associated with TL in nestlings of wild purple-crowned fairy-wrens ( Malurus coronatus ), endangered songbirds of the monsoonal tropics. We found that higher average maximum air temperature (range 31 to 45 °C) during the nestling period was associated with shorter early-life TL. This effect was mitigated by water availability (i.e., during the wet season, with rainfall), but independent of other pertinent environmental conditions, implicating a direct effect of heat exposure. Models incorporating existing information that shorter early-life TL predicts shorter lifespan and reduced fitness showed that shorter TL under projected warming scenarios could lead to population decline across plausible future water availability scenarios. However, if TL is assumed to be an adaptive trait, population viability could be maintained through evolution. These results are concerning because the capacity to change breeding phenology to coincide with increased water availability appears limited, and the evolutionary potential of TL is unknown. Thus, sublethal climate warming effects early in life may have repercussions beyond individual fitness, extending to population persistence. Incorporating the delayed reproductive costs associated with sublethal heat exposure early in life is necessary for understanding future population dynamics with climate change.

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confidence: 99%

Hot and dry conditions predict shorter nestling telomeres in an endangered songbird: Implications for population persistence

Eastwood

Connallon

Delhey

et al. 2022

Proc. Natl. Acad. Sci. U.S.A.

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“…Defecation rate of red knots feeding on molluscs can be as high as 0.5 droppings/min (Gonzalez et al, 1996). Therefore, CORTm can be used as a non‐invasive indicator of avian physiological stress responses to short‐term stressors (minutes‐to‐hours) such as heat events (Moagi et al, 2021).…”

Section: Methodsmentioning

confidence: 99%

“…There is accumulating evidence that glucocorticoid hormones mediate escape responses (Seltmann et al, 2012;Thaker et al, 2010) as well as behavioural and physiological responses to high environmental temperatures (Mentesana & Hau, 2022;Moagi et al, 2021). Nonetheless, environmental variation could modulate behaviour and physiology differently, and thus the extent to which behavioural stress responses are representative of physiological stress responses or vice versa (Tablado et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, although many studies have investigated species sensitivity to human disturbance by focusing on either behavioural or physiological parameters (typically FID or glucocorticoid levels), little is known about the relationship between physiological and behavioural stress coping mechanisms (Tablado et al, 2021). There is accumulating evidence that glucocorticoid hormones mediate escape responses (Seltmann et al, 2012; Thaker et al, 2010) as well as behavioural and physiological responses to high environmental temperatures (Mentesana & Hau, 2022; Moagi et al, 2021). Nonetheless, environmental variation could modulate behaviour and physiology differently, and thus the extent to which behavioural stress responses are representative of physiological stress responses or vice versa (Tablado et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

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Heat stress increases risk taking in foraging shorebirds

et al. 2023

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1. Animals often face a trade-off between food acquisition and predation/disturbance avoidance. Yet, the extent to which this trade-off is affected by modulating factors such as thermal risk and foraging opportunities has been largely overlooked.2. Here, we examined the influence of temporal and environmental gradients on the flight initiation distance (FID, the distance at which animals flee from an approaching human-simulated predator) and escape mode (flying/low risk versus running/low cost) in 16 species of shorebirds foraging on tidal flats of the Bijagós Archipelago, Guinea-Bissau. We measured escape responses throughout the low tide period during wet and dry seasons and simultaneously recorded microclimate variables and occurrence of heat-reduction behaviour (ptiloerection). Furthermore, we measured corticosterone metabolites (CORTm) from droppings in red knots Calidris canutus to assess whether ptiloerection is associated to a physiological stress response to hot conditions.3. Overall, birds tolerated a closer approach at higher environmental temperatures and when showing ptiloerection. They also had shorter FIDs during the dry season and towards the start/end of the low tide period. FIDs also increased with body mass and decreased in areas with more human presence. In red knots, individuals showing ptiloerection had higher levels of CORTm, demonstrating a link between physiological and behavioural stress coping responses to heat events. 4. Our results suggest that heat-stressed shorebirds take greater risks, supporting the idea of a thermoregulation-predation risk trade-off. They also indicate that shorebirds adjust risk taking to tidal and seasonal cycles, generally reducing FIDs when the energetic costs of escape are expected to be large. Finally, they suggest that shorebirds habituate to non-lethal human presence and respond to perceived predation risk in accordance with the predictions of optimal escape theory.5. These results are relevant to many animals that face a tight window for foraging activity while being exposed to predation/disturbance and heat during the day. We discuss management implications of our results in the context of global change.

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“…For example, when hot days occurred for several consecutive days in Southern and Western Europe in 2003, it resulted in an estimated 70,000 heatrelated human deaths (Robine et al, 2008) and was followed by detectable decreases in wild bird populations (Jiguet et al, 2006). However, even a single hot day can cause acute heat stress and have metabolic costs (Moagi et al, 2021). Extreme hot weather affects reproductive success negatively in a wide range of taxa, including both ectothermic (Zizzari and Ellers, 2011;Dayananda et al, 2017) and endothermic animals (Welbergen et al, 2008;Conrey et al, 2016;Marrot et al, 2017;Woodroffe et al, 2017;Van de Ven et al, 2020;Bourne et al, 2021;McCowan and Griffith, 2021;Oswald et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

Extreme Hot Weather Has Stronger Impacts on Avian Reproduction in Forests Than in Cities

et al. 2022

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Climate change and urbanisation are among the most salient human-induced changes affecting Earth’s biota. Extreme weather events can have high biological impacts and are becoming more frequent recently. In cities, the urban heat island can amplify the intensity and frequency of hot weather events. However, the joint effects of heat events and urban microclimate on wildlife are unclear, as urban populations may either suffer more from increased heat stress or may adapt to tolerate warmer temperatures. Here, we test whether the effects of hot weather on reproductive success of great tits (Parus major) are exacerbated or dampened in urban environments compared to forest habitats. By studying 760 broods from two urban and two forest populations over 6 years, we show that 14–16 days-old nestlings have smaller body mass and tarsus length, and suffer increased mortality when they experience a higher number of hot days during the nestling period. The negative effects of hot weather on body mass and survival are significantly stronger in forests than in urban areas, where these effects are dampened or even reversed. These results suggest that urban nestlings are less vulnerable to extreme hot weather conditions than their non-urban conspecifics. This difference might be the result of adaptations that facilitate heat dissipation, including smaller body size, altered plumage and reduced brood size. Alternatively or additionally, parental provisioning and food availability may be less affected by heat in urban areas. Our findings suggest that adaptation to heat stress may help birds cope with the joint challenges of climate change and urbanisation.

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Hot days are associated with short-term adrenocortical responses in a southern African arid-zone passerine bird

Cited by 24 publications

References 54 publications

Hot and dry conditions predict shorter nestling telomeres in an endangered songbird: Implications for population persistence

Hot and dry conditions predict shorter nestling telomeres in an endangered songbird: Implications for population persistence

Heat stress increases risk taking in foraging shorebirds

Extreme Hot Weather Has Stronger Impacts on Avian Reproduction in Forests Than in Cities

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