Coat color mismatch improves survival of a keystone boreal herbivore: Energetic advantages exceed lost camouflage

Kennah, Joanie L; Peers, Michael J. L.; Wal, Eric Vander; Majchrzak, Yasmine N.; Menzies, Allyson K.; Studd, Emily K.; Boonstra, Rudy; Humphries, Murray M.; Jung, Thomas S.; Kenney, Alice J.; Boutin, Stan

doi:10.1002/ecy.3882

Cited by 7 publications

(5 citation statements)

References 63 publications

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“…This explanation will require details on the degree to which white or brown hares are mismatched with the changing timing of snow cover. Alternative explanations are that coat colour affects insulation, which in turn affects energetic requirements, foraging time and predator exposure, or that coat colour is an indicator of age, body weight, nutrient status, parasite loads and body condition, all of which could affect survival [ 49 ]. There is much left to do to understand the ecological effects of the changing timing of winter moulting of mammals in northern ecosystems.…”

Section: Discussionmentioning

confidence: 99%

Does coat colour influence survival? A test in a cyclic population of snowshoe hares

et al. 2023

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Some mammal species inhabiting high-latitude biomes have evolved a seasonal moulting pattern that improves camouflage via white coats in winter and brown coats in summer. In many high-latitude and high-altitude areas, the duration and depth of snow cover has been substantially reduced in the last five decades. This reduction in depth and duration of snow cover may create a mismatch between coat colour and colour of the background environment, and potentially reduce the survival rate of species that depend on crypsis. We used long-term (1977–2020) field data and capture–mark–recapture models to test the hypothesis that whiteness of the coat influences winter apparent survival in a cyclic population of snowshoe hares ( Lepus americanus ) at Kluane, Yukon, Canada. Whiteness of the snowshoe hare coat in autumn declined during this study, and snowshoe hares with a greater proportion of whiteness in their coats in autumn survived better during winter. However, whiteness of the coat in spring did not affect subsequent summer survival. These results are consistent with the hypothesis that the timing of coat colour change in autumn can reduce overwinter survival. Because declines in cyclic snowshoe hare populations are strongly affected by low winter survival, the timing of coat colour change may adversely affect snowshoe hare population dynamics as climate change continues.

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Section: Discussionmentioning

confidence: 99%

Does coat colour influence survival? A test in a cyclic population of snowshoe hares

et al. 2023

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“…In addition to cryptic coloration, thermoregulatory properties associated with coloration have been proposed as an alternative or complementary function for polymorphic and seasonally color changing species in winter environments. For example, winter white pelages in seasonally color changing mammals are more insulative than brown summer coats and further, the winter coats of more northerly snowshoe hare are longer and denser than those of hares in lower latitudes (Gigliotti et al 2017, Zimova et al 2018, Kennah et al 2023). Similarly for a polymorphic raptor, denser contour feather structure has been found in the gray morph of the tawny owl S. aluco , providing increased plumage insulative capacity over red morph individuals (Koskenpato et al 2016).…”

Section: Discussionmentioning

confidence: 99%

Survival of a polymorphic species in seasonally snow‐covered forests

Murphy,

Pauli,

Shipley

et al. 2023

Oikos

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Color polymorphism is an adaptive strategy in which a species exhibits multiple color phenotypes in a population. Often, phenotypes are variably suited to different environmental conditions which may buffer the population against variable conditions. Modern climate change is creating novel selective pressures for many species, especially in winter habitats. Few studies have quantified the benefits of polymorphism for allowing species to cope with climate‐induced environmental change, particularly for species with more cryptic differences between morphs. We investigated how color polymorphism mediates selective pressures in ruffed grouse Bonasa umbellus, a winter‐adapted bird species of North American forests. Ruffed grouse display phenotypic variation in plumage color, ranging from red to gray. Over five winters (2015–2022), we monitored weather conditions, habitat use, and weekly survival for 94 grouse to test whether individuals had lower survival when phenotypically mismatched with snow cover (e.g. a gray bird on a snowless landscape or a red bird in snow). Grouse phenotypically mismatched with snow cover had lower survival, but only when winter survival rates were lowest. During winters of lower overall survival, red grouse exhibited higher survival during snow‐free periods, whereas gray grouse had higher survival when snow was present. We also found that open habitat negatively impacted survival, regardless of color. While the effect of phenotypic mismatch was variable among years, it was a stronger predictor of survival than land cover, suggesting that snow is an important habitat feature mediating overwinter survival. Our work offers an advancement in understanding how environmental variability affects geographic variation in and maintenance of multiple color phenotypes in seasonally‐snow covered environments. Our finding that interactions between color morph and snow cover are important for conferring winter survival provides further evidence that color polymorphism may serve as a buffer against rapidly changing conditions and a pathway for persistence of polymorphic species.Keywords: Bonasa umbellus, color polymorphism, phenotypic mismatch, ruffed grouse, winter ecology, Wisconsin

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Section: Discussionmentioning

confidence: 99%

Survival of a polymorphic species in seasonally snow-covered forests

Murphy

Pauli

Shipley

et al. 2023

Preprint

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Color polymorphism is an adaptive strategy in which a species exhibits multiple color phenotypes in a population. Often times, phenotypes are variably suited to different environmental conditions which may buffer the population against variable conditions. Modern climate change is creating novel selective pressures for many species, especially in winter habitats. Few studies have quantified the benefits of polymorphism for allowing species to cope with climate-induced environmental change. We investigated how color polymorphism mediates selective pressures in ruffed grouse Bonasa umbellus, a widespread and winter-adapted bird species of North American forests. Ruffed grouse display phenotypic variation in plumage color, ranging from red to gray. Over five winter seasons (2015-2022), we monitored weather conditions, habitat use, and weekly survival for 94 ruffed grouse to test whether individuals had lower survival when grouse were phenotypically mismatched with snow cover (e.g., a gray bird on a snowless landscape or a red bird in snow). Grouse phenotypically mismatched with snow cover had lower survival, but only when winter survival rates were lowest. During winters of lower overall survival, red grouse exhibited higher survival during snow-free periods, whereas gray grouse had higher survival when snow was present. We also found that open habitat negatively impacted survival, regardless of color. While the effect of phenotypic mismatch was variable among years, it was a stronger predictor of winter survival than land cover features, suggesting that snow is an important habitat feature mediating overwinter survival. Our work offers an advancement in understanding how environmental variability affects geographic variation in and maintenance of multiple color phenotypes in seasonally-snow covered environments. Our finding that interactions between color morph and snow cover are important for conferring winter survival provides further evidence that color polymorphism may serve as a buffer against rapidly changing conditions and a pathway for persistence of polymorphic species.

show abstract

Coat color mismatch improves survival of a keystone boreal herbivore: Energetic advantages exceed lost camouflage

Cited by 7 publications

References 63 publications

Does coat colour influence survival? A test in a cyclic population of snowshoe hares

Does coat colour influence survival? A test in a cyclic population of snowshoe hares

Survival of a polymorphic species in seasonally snow‐covered forests

Survival of a polymorphic species in seasonally snow-covered forests

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