Quantifying structural variation in contour feathers to address functional variation and life history trade‐offs

Butler, Luke K.; Rohwer, Sievert; Speidel, Markus G.

doi:10.1111/j.1600-048x.2008.04432.x

Cited by 39 publications

(70 citation statements)

References 27 publications

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“…Feathers of high quality are important in all stages of a bird’s life [24], [56], [57]. Moult typically leads to improved flight performance [58], while flying with feather gaps in the wings or with severely worn feathers increases energy expenditure [28], [59], [60].…”

Section: Discussionmentioning

confidence: 99%

Flight Performance and Feather Quality: Paying the Price of Overlapping Moult and Breeding in a Tropical Highland Bird

Echeverry‐Galvis

Hau

2013

PLoS ONE

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A temporal separation of energetically costly life history events like reproduction and maintenance of the integumentary system is thought to be promoted by selection to avoid trade-offs and maximize fitness. It has therefore remained somewhat of a paradox that certain vertebrate species can undergo both events simultaneously. Identifying potential costs of overlapping two demanding life history stages will further our understanding of the selection pressures that shape the temporal regulation of life history events in vertebrates. We studied free-living tropical Slaty brush-finches (Atlapetes schistaceus), in which individuals spontaneously overlap reproduction and moult or undergo both events in separation. To assess possible costs of such an overlap we quantified feather quality and flight performance of individuals in different states. We determined individual’s life history state by measuring gonad size and scoring moult stage, and collected a newly grown 7th primary wing feather for later analysis of feather quality. Finally, we quantified flight performance for each individual in the wild. Overlapping individuals produced lighter and shorter wing feathers than individuals just moulting, with females decreasing feather quality more strongly during the overlap than males. Moreover, overlapping individuals had a reduced flight speed during escape flights, while their foraging flight speed was unaffected. Despite overlappers being larger and having a smaller wing area, their lower body mass resulted in a similar wing load as in breeders or moulters. Individuals measured repeatedly in different states also showed significant decreases in feather quality and escape flight speed during the overlap. Reduced escape flight speed may represent a major consequence of the overlap by increasing predation risk. Our data document costs to undergoing two life history stages simultaneously, which likely arise from energetic trade-offs. Impairments in individual quality and performance may represent important factors that select for temporal separation of life history stages in other species.

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Section: Discussionmentioning

confidence: 99%

Flight Performance and Feather Quality: Paying the Price of Overlapping Moult and Breeding in a Tropical Highland Bird

Echeverry‐Galvis

Hau

2013

PLoS ONE

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“…The functional relationships between our measures of feather size and quality are also diverse. Feather mass has been shown to correlate with number of barbs, and hence the tightness of feather surface (Butler et al, 2008). Feather tightness enhances heat absorption and sustained flight (Butler et al, 2008) and resistance to abrasion (Dawson et al, 2000).…”

Section: Discussionmentioning

confidence: 99%

“…Feather mass has been shown to correlate with number of barbs, and hence the tightness of feather surface (Butler et al, 2008). Feather tightness enhances heat absorption and sustained flight (Butler et al, 2008) and resistance to abrasion (Dawson et al, 2000). Feather length affects take‐off speed and manoeuvrability (Swaddle et al, '96; Matyjasiak et al, 2004), and hence predator escape.…”

Section: Discussionmentioning

confidence: 99%

Effects of immune activation and glucocorticoid administration on feather growth in greenfinches

Männiste

Hõrak

2011

J. Exp. Zool.

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Elevation of glucocorticoid (GC) hormone levels is an integral part of stress response (as well as its termination) and immunomodulation. These hormones are also responsible for mobilizing energy stores by stimulation of gluconeogenesis and inhibition of protein synthesis. Elevation of GCs is thus incompatible with other protein-demanding processes, such as moult. Previous studies have shown that chronic elevation of GC hormones suppresses feather growth. Here, we asked whether similar effect would also occur in the case of acute GC elevation and induction of an inflammatory response by foreign antigen. We performed an experiment on captive wild-caught greenfinches (Carduelis chloris) injecting birds with phytohaemagglutinin (PHA) and dexamethasone (DEX) in a factorial design. To assess the possible somatic impacts of these manipulations, we removed one of the outermost tail feathers before the experiment and measured mass and rachis diameter and length of the replacement feathers grown in captivity. Immunostimulation by PHA reduced rachis length, but did not affect feather mass or rachis diameter. Single injection of a synthetic GC hormone DEX significantly reduced all three parameters of feather size. Altogether, these findings demonstrate the sensitivity of feather growth to manipulation of immune and adrenal functions. Our results corroborate the somatic costs of immune activation and suggest that even a short-term elevation of GC hormones may induce long-term somatic costs with a potential impact on fitness. Our findings also imply that a single injection of DEX, frequently used as a diagnostic tool, can have lasting effects and researchers must consider this when designing experiments.

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“…Thermoinsulation is thought to be conferred by different components of the body feathers than those used for a waterproofing function (Middleton ; Butler, Rohwer & Speidel ; Broggi et al . ).…”

Section: Introductionmentioning

confidence: 99%

“…Thus, the thermoregulatory characteristics of body feathers are probably related to a range of structural traits, including the length of the downy section and the density of barbs and barbules. These traits combine to contribute to the depth and structure of the downy plumage layer (Middleton ; Butler, Rohwer & Speidel ; Davenport et al . ; de Zwaan, Greenwood & Martin ), and determine the number and size of trapped air spaces near the skin.…”

Section: Introductionmentioning

confidence: 99%

A phylogenetic comparative analysis reveals correlations between body feather structure and habitat

et al. 2017

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Summary Body feathers ensure both waterproofing and insulation in waterbirds, but how natural variation in the morphological properties of these appendages relates to environmental constraints remains largely unexplored. Here, we test how habitat and thermal condition affect the morphology of body feathers, using a phylogenetic comparative analysis of five structural traits [i.e., total feather length, the lengths of the pennaceous (distal) and plumulaceous (proximal) sections, barb density, and pennaceous barbule density] from a sample of 194 European bird species. Body feather total length is shorter in aquatic than in terrestrial birds, and this difference between groups is due to the shorter plumulaceous feather section in aquatic birds. Indeed, a reduced plumulaceous section in feather length probably reflects the need to limit air trapped in the plumage to adjust the buoyancy of aquatic birds. In contrast, the high pennaceous barbule density of aquatic birds compared to their terrestrial counterparts reflects water resistance of the plumage in contact with water. Our results show that birds living in environments with low ambient temperature have long plumulaceous feather lengths, low barb density, and low pennaceous barbule density. Data also suggest that plumage probably has limited function in reducing the heat absorption of species living in hot environments. Our results have broad implications for understanding the suite of selection pressures driving the evolution of body feather functional morphology. It remains to be tested, however, how other feather traits, such as the density of plumage (feathers per unit area) and the relative number of different feather types, for example downy feathers, are distributed amongst birds with different water resistance and thermoinsulative needs. A http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.12820/suppinfo is available for this article.

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Quantifying structural variation in contour feathers to address functional variation and life history trade‐offs

Cited by 39 publications

References 27 publications

Flight Performance and Feather Quality: Paying the Price of Overlapping Moult and Breeding in a Tropical Highland Bird

Flight Performance and Feather Quality: Paying the Price of Overlapping Moult and Breeding in a Tropical Highland Bird

Effects of immune activation and glucocorticoid administration on feather growth in greenfinches

A phylogenetic comparative analysis reveals correlations between body feather structure and habitat

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