The origin of feather holes: a word of caution

Vágási, Csongor I.

doi:10.1111/jav.00359

Cited by 11 publications

(20 citation statements)

References 47 publications

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“…3 in Jenni-Eiermann et al, 2015), but they did not report the formation of fault bars. Although fault bars and pale bands are both feather malformations, they appear to have different proximal causes; thus, we advocate treating fault bars, feather holes, and pale bands as different phenomena (Pap et al, 2007;Vágási, 2014), while we encourage studying them simultaneously.…”

Section: Introductionmentioning

confidence: 97%

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Fault bars in bird feathers: mechanisms, and ecological and evolutionary causes and consequences

Jovani

Rohwer

2016

Biological Reviews

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Fault bars are narrow malformations in feathers oriented almost perpendicular to the rachis where the feather vein and even the rachis may break. Breaks in the barbs and barbules result in small pieces of the feather vein being lost, while breaks in the rachis result in loss of the distal portion of the feather. Here, we provide a comprehensive review of 74 papers on fault bar formation in hopes of providing a clearer approach to their study. First, we review the evidence that the propensity to develop fault bars is modified by natural selection. Given that fault bars persist in the face of survival costs, we conclude that they must be an unfortunate consequence of some alternative adaptation that outweighs the fitness costs of fault bars. Second, we summarize evidence that the development of fault bars is triggered by psychological stress such as that of handling or predation attempts, and that they persist because the sudden contractions of the muscles in the feather follicle that control fright moults also causes the development of fault bars in growing feathers. Third, we review external and physiological (e.g. corticosterone) agents that may affect the likelihood that an acute stress will result in a growing feather exhibiting a fault bar. These modifying factors have often been treated as fundamental causes in the earlier literature on fault bars. Fourth, we then use this classification to propose a tentative model where fault bars of different severity (from light to severe) are the outcome of the interaction between the propensity to produce fault bars (which differs between species, individuals and feather follicles within individuals) and the intensity of the perturbation. This model helps to explain contradictory results in the literature, to identify gaps in our knowledge, and to suggest further studies. Lastly, we discuss ways in which better understanding of fault bars can inform us about other aspects of avian evolutionary ecology, such as the physiology of moult, the integration of moult into avian life cycles, and the strategies used to minimize stress during moult. Moreover, the study of fault bars may be relevant to understanding the aerodynamics of flight and the early evolution of flight.

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Section: Introductionmentioning

confidence: 97%

“…A recent review convincingly suggested that feather holes 0.5-1 mm in diameter (also called 'fault spots' by Murphy et al, 1989) may be related to fault bars (Vágási, 2014). Previously, these holes were attributed to chewing lice (e.g.…”

Section: Introductionmentioning

confidence: 98%

Fault bars in bird feathers: mechanisms, and ecological and evolutionary causes and consequences

Jovani

Rohwer

2016

Biological Reviews

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“…), whereas feather holes are small defects (diameter 0.5–1 mm) of the vane (Vas et al . , Vágási ). Feather structural damage could decrease flight feather quality and/or create asymmetry in the wing and tail.…”

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confidence: 99%

Feather‐degrading bacteria, uropygial gland size and feather quality in House SparrowsPasser domesticus

Fülöp

Czirják

Pap

et al. 2016

Ibis

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2Feathers are dead integumentary structures that are prone to damage and thus show gradual degradation over the course of a year. This loss of quality might have negative fitness consequences. Feather-degrading bacteria are some of the most prevalent featherdegrading organisms, yet the relationship between feather-degrading bacteria load and flight feather quality has rarely been assessed. We studied this relationship in free-living House Sparrows during breeding and non-breeding annual lifecycle stages. We also considered the size of the uropygial gland, given the antimicrobial function of its secretions, and the effect of body condition. The number of feather holes was positively associated with feather-degrading bacteria load and was negatively related to uropygial gland size and body condition during the breeding season in both sexes. In the non-breeding season we found the same relationships, but only in females. The degree of feather wear was unrelated to any of the variables measured during the breeding season, whereas it was negatively associated with uropygial gland size and positively with feather-degrading bacteria load in the non-breeding season, but only in females. Our results suggest that feather-degrading bacteria may induce the formation of feather holes, but play only a minor role in the abrasion of flight feathers.

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“…Feathers are inert integumentary appendages of birds that wear down and break gradually under natural conditions and are then replaced during moult (Vágási et al . , Vágási ). Physical abrasion, which primarily results from the impact of airborne particles and contact with different objects in the environment (Barrowclough & Sibley , Burtt , Bonser ), as well as from parasites such as feather lice, is thought to cause holes in feathers, though this conclusion is still controversial (Pap et al .…”

mentioning

confidence: 99%

“…, Vas et al . , Vágási ). Feather‐degrading bacteria have only relatively recently received attention as causitive agents resulting in feather abrasion, primarily as a consequence of the seminal work of Burtt and Ichida ().…”

mentioning

confidence: 99%

Bacterial degradability of white patches on primary feathers is associated with breeding date and parental effort in a migratory bird

Ruiz-de-Castañeda

Burtt

González‐Braojos

et al. 2015

Ibis

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We compared the in vitro bacterial degradability of the white patch and melanized area of primary feathers of breeding male and female Pied Flycatchers Ficedula hypo‐leuca and related this variation to laying date, brood size and brood mass. Bacterial degradability of male and female white feather patches, but not of melanized areas, was positively correlated with laying date. Male Pied Flycatchers showed a positive correlation between bacterial degradability of the white patch, though not of the melanized patch, and brood size and brood mass. Feather degradability appears to be negatively related to individual quality and positively related to reproductive effort.

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The origin of feather holes: a word of caution

Cited by 11 publications

References 47 publications

Fault bars in bird feathers: mechanisms, and ecological and evolutionary causes and consequences

Fault bars in bird feathers: mechanisms, and ecological and evolutionary causes and consequences

Feather‐degrading bacteria, uropygial gland size and feather quality in House SparrowsPasser domesticus

Bacterial degradability of white patches on primary feathers is associated with breeding date and parental effort in a migratory bird

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