Gray plumage color is more cryptic than brown in snowy landscapes in a resident color polymorphic bird

Koskenpato, Katja; Lehikoinen, Aleksi; Lindstedt, Carita; Karell, Patrik

doi:10.1002/ece3.5914

Cited by 22 publications

(29 citation statements)

References 58 publications

(90 reference statements)

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“…It is likely there are survival costs associated with the presence of snow on the ground, possibly due to phenotypic mismatch [38,39]. Interestingly, exposure to deep snow did not influence overall survival, but individuals that selected deep snow were more likely to survive the winter.…”

Section: (A) Personality and Behavioural Plasticity In Roost Site Selectionmentioning

confidence: 97%

“…For species that do not moult white in winter, even slight differences in coloration can influence the effectiveness of crypsis in snow, with consequences for overwinter survival. For example, brown morph tawny owls (Strix aluco) are more visible than grey morph individuals against a snowcovered landscape [38], and are less likely to survive during snowy winters [39]. For other winter-adapted species, such as ruffed grouse (Bonasa umbellus), which has brown plumage year-round, snow cover may result in phenotypic mismatch, exposing grouse to predators.…”

Section: Introductionmentioning

confidence: 99%

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Personality differences in the selection of dynamic refugia have demographic consequences for a winter-adapted bird

2020

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For overwintering species, individuals' ability to find refugia from inclement weather and predators probably confers strong fitness benefits. How animals use their environment can be mediated by their personality (e.g. risk-taking), but does personality mediate how overwintering species select refugia? Snow cover is a dynamic winter characteristic that can influence crypsis or provide below-the-snow refugia. We explored how wintering ruffed grouse ( Bonasa umbellus ) selected snow roosting sites, a behaviour that reduces stress and cold exposure. We linked selection for approximately 700 roosts with survival of 42 grouse, and showed that grouse generally selected deeper snow and warmer areas. Grouse found in shallow snow were less likely to survive winter. However, individuals that selected deep snow improved their survival, suggesting that demographic consequences of selecting winter refugia are mediated by differences in personality . Our study provides a crucial, and seldom addressed, link between personality in resource selection and resulting demographic consequences.

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Section: (A) Personality and Behavioural Plasticity In Roost Site Selectionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Personality differences in the selection of dynamic refugia have demographic consequences for a winter-adapted bird

2020

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“…In order to achieve such information, we need empirical studies of natural populations where this variation can be monitored. Evidence is accumulating that colour polymorphism-a phenotypic marker for genetic polymorphism-is associated with morph-specificity in habitat use (Galeotti and Cesaris 1996;Dreiss et al 2011; Passarotto et al 2018;Koskenpato et al 2020) and differential fitness depending on environmental conditions (Karell et al 2011a;Emaresi et al 2014;San-José et al 2019). Such differences are expected to reflect variations in food resource use and diet specialisation.…”

Section: Discussionmentioning

confidence: 99%

“…These cyclic food conditions limit the reproduction of tawny owls in this environment as in low vole cycle phases tawny owls often skip breeding (Karell et al 2009a). In general, the grey tawny owls are more common in dry and cold areas (Galeotti and Cesaris 1996;PK et al unpublished data), and they are adapted to resist snow-rich and cold winters (Karell et al 2011a), presumably because they have lower energy requirements in extremely cold conditions (Piault et al 2009;Karell et al 2011a;Koskenpato et al 2016Koskenpato et al , 2020. In concordance with this, the life span of the grey morph is indeed longer than that of the brown morph at the Northern limit of the species range (Brommer et al 2005).…”

Section: Discussionmentioning

confidence: 99%

Specialist predation covaries with colour polymorphism in tawny owls

Karell

Kohonen

Koskenpato

2021

Behav Ecol Sociobiol

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Understanding intraspecific phenotypic variation in prey specialisation can help to predict how long-term changes in prey availability affect the viability of these phenotypes and their persistence. Generalists are favoured when the main food resources are unpredictable compared to specialists, which track the availability of the main prey and are more vulnerable to changes in the main food resource. Intraspecific heritable melanin-based colour polymorphism is considered to reflect adaptations to different environments. We studied colour morph-specific diet specialisation in a generalist predator, tawny owl (Strix aluco), during offspring food provisioning in relation to mammal prey density. We hypothesised that the grey morph, with higher fitness than the brown in Northern boreal conditions, is more specialised in mammalian prey than the brown morph, which in turn has higher fitness than the grey in the temperate zone. We found a higher diversity of prey delivered to the nest by brown fathers compared to grey ones, which also depended on the overall mammalian prey availability. Brown fathers provided proportionally fewer mammalian prey than grey in poor, but not in favourable mammal prey years. Our results suggest that the brown morph is more generalistic and reacts more strongly to variations in food supply than the grey morph, which may be a beneficial strategy in an unpredictable environment caused by environmental degradation. Significance statement Diet choice of a species may vary depending on fluctuations in the abundance of their food resource, but also within a population, there can be adaptations to use different food resources. The tawny owl exhibits a grey and a reddish-brown colour morph and is considered a generalist predator eating both mammal and bird prey. We find that the diet of the reddish-brown morph is more diverse than that of the grey. When the tawny owls’ main prey, small mammals, are abundant both colour morphs prey on mammals, but in years with less small mammals, the reddish-brown morph is more prone of switching to small bird predation than the grey. The generalist strategy of the brown morph is likely to be more favourable than a stricter specialisation in small mammals of the grey under recently reoccurring irregularities in small mammal dynamics.

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“…The grey morph is suggested to avoid predation better in snowy winter conditions and the brown (red) morph should do better in less snowy circumstances. This camouflage effect has been assessed in a citizen science study in which pictures of grey and brown Tawny Owls in various backgrounds were shown to human observers (Koskenpato et al 2020). It has been suggested that the recent increase of brown Tawny Owls in Finland (1961Finland ( -2008 is a consequence of warmer and less snowy winters due to climate warming (Karell et al 2011).…”

mentioning

confidence: 99%

Significance of plumage colour for winter survival in the Tawny Owl (Strix aluco): revisiting the camouflage hypothesis

Solonen¹

2021

Ibis

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In snowy winters, the survival of Tawny Owls Strix aluco of the grey colour morph is suggested to be better than that of the brown (or red) morph, partly due to their paler plumage, which is presumed to provide better camouflage against predation. If the difference in the susceptibility to predation between the colour morphs is significant, this should probably be reflected in the relation between the number of snow‐covered days (i.e. the length of the winter) and the number and survival of owls of different colour. In a population in southern Finland there were no significant associations between the number of snowy days during winter and the number of breeding Tawny Owls of different colour morphs in the following spring, but the number of owls, in particular red ones, varied inversely with the number of snowy days in the winter of the previous year. The time lag suggests that the number of snow‐covered days (or some related factors) primarily influenced the pre‐breeding survival of young red owls. However, I found no effect of snow days on the proportion of colour morphs, suggesting only small differences in morph‐specific survival under long‐lasting winter conditions.

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Gray plumage color is more cryptic than brown in snowy landscapes in a resident color polymorphic bird

Cited by 22 publications

References 58 publications

Personality differences in the selection of dynamic refugia have demographic consequences for a winter-adapted bird

Personality differences in the selection of dynamic refugia have demographic consequences for a winter-adapted bird

Specialist predation covaries with colour polymorphism in tawny owls

Significance of plumage colour for winter survival in the Tawny Owl (Strix aluco): revisiting the camouflage hypothesis

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