The dark side of birds: melanism—facts and fiction

Grouw, Hein van

doi:10.25226/bboc.v137i1.2017.a9

Cited by 19 publications

(10 citation statements)

References 30 publications

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“…van Grouw (2012Grouw ( , 2013Grouw ( , 2017 and Mahabal et al (2016) Brown Characterized by a qualitative reduction of eumelanin (producing black, brown or grey coloration). The number of granules of eumelanin pigment remains unaffected but because eumelanin is not fully oxidized, the plumage coloration is changed; the pheomelanin (giving rise to lighter yellowish to reddish colorations) remains unchanged.…”

Section: Colour Aberration Description Sourcementioning

confidence: 99%

“…2013, van Grouw 2013, Hume & van Grouw 2014). In the past, aberrantly coloured individuals were sometimes described as new species (Brisson 1760, Vigors 1825, Dybowski 1916, van Grouw 2017). Despite this long‐term interest in plumage colour aberrations, most published studies are anecdotal, documenting only a single or a few field observations of aberrantly coloured birds or a limited number of colour aberration types (Ławicki & Grabowski 2009, Maniarski & Ciach 2012, Møller et al .…”

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confidence: 99%

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A large‐scale survey of bird plumage colour aberrations reveals a collection bias in Internet‐mined photographs

Zbyryt¹,

Mikula

Ciach

et al. 2020

Ibis

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Birds with plumage colour aberrations are of interest to both the general public and scientists. However, due to their rarity in nature, information on the presence of colour aberrations is rarely found in the peer‐reviewed literature. Exploration of public observations using modern information technologies such as Internet‐based search engines could facilitate cost‐effective and rapid broad‐scale collection of data on phenotypic aberrations in animals but may also be prone to the same problems as fieldwork, including systematic collection bias. We used Google Images and also asked birdwatchers and ornithologists, via naturalists' forums and social media, to collate a unique dataset of photographs of 936 aberrantly coloured birds of 74 species from Poland. Phylogenetically informed analyses, which included species both with and without reported colour aberrations, revealed that the number of colour aberrations was higher in species with larger populations in Poland, those with larger body size, and those associated with human settlements. Colour aberrations were also more often reported for species with a wider habitat breadth and those which do not migrate over long distances. Habitat openness and diet type were not related to the number of colour aberrations across species in multivariate models. Our study emphasizes not only the power of novel sources to collect large datasets on relatively rare phenotypic aberrations in animals but also the importance of vigilance when using data mined from public sources because the observed patterns may reflect collection bias rather than the nature of the studied phenomena.

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Section: Colour Aberration Description Sourcementioning

confidence: 99%

mentioning

confidence: 99%

A large‐scale survey of bird plumage colour aberrations reveals a collection bias in Internet‐mined photographs

Zbyryt¹,

Mikula

Ciach

et al. 2020

Ibis

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“…Although the expression of melanin‐based plumage colour is thought to be less phenotypically plastic than the expression of carotenoid‐based coloration (Roulin & Ducrest ), melanization in birds is known to be affected by a range of factors, including hormone production, environment and social conditions (Price ). Thus it might be possible that dark larks settling on a pale substrate could, at their next moult, produce feathers with a lower concentration of eumelanin, a different distribution of melanin granules (van Grouw ) or a different feather microstructure, giving them a paler appearance. Plumage coloration appears to be under the control of a very small number of genes (Toews et al .…”

Section: Processes Of Substrate Colour‐matchingmentioning

confidence: 99%

Possible mechanisms of substrate colour‐matching in larks (Alaudidae) and their taxonomic implications

Donald

Alström

Engelbrecht

2017

Ibis

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“…For instance, darker colour is supposedly favoured in cooler climates since dark individuals (i.e., lower skin reflectance) have an advantage under low temperature conditions, as they heat up faster than lighter individuals (Clusella- Trullas et al 2007;Hodges 2018). Melanism occurs when the quantity of skin melanin pigment is found in large amounts at the expense of other colours (Majerus 1998;van Grouw 2017;Mărănducă et al 2019). This can lead to animal populations with complete melanistic individuals that display an entirely black colour phenotype or variants such as melanotic (nearly entirely expressed melanism) or pseudo-/partial-melanism (Majerus 1998;Zuffi 2008;Domeneghetti et al 2016).…”

Section: Introductionmentioning

confidence: 99%

Melanism in the grass snake Natrix natrix (Linnaeus, 1758) from the Danube Delta Biosphere Reserve, Romania

Fănaru¹,

Telea²,

Gherghel³

et al. 2022

Herpetozoa

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Animal colouration has a significant ecological role in defence, reproduction, and thermoregulation. In the case of melanism, it is a complex topic. Besides potential disadvantages such as higher risk of predation, melanistic ectotherms may have certain physiological advantages such as more efficient thermoregulation in colder climates and thus, reduced basking time. The common grass snake (Natrix natrix) is a widespread species throughout Europe and Asia. It exhibits a wide range of colour polymorphisms, from olive to dark grey, even albinistic and melanistic. Between 2016 and 2021, we conducted fieldwork in the Danube Delta Biosphere Reserve (DDBR) with the aim to document the geographic range of melanistic grass snakes. We categorised the melanistic expressions of N. natrix individuals as melanotic, completely melanistic, and partially melanistic. Melanistic snakes were encountered in all six localities visited, suggesting that the occurrence of melanistic grass snakes in the DDBR is geographically widespread. We observed both juveniles (n=2) and adults (n=11) with melanism, suggesting that individuals are born melanistic. However, the proportion of melanistic individuals in the general population of N. natrix from the DDBR is unknown. Only at Histria locality we studied the proportion of melanism in the grass snake population and 6.3% of the snakes caught were melanistic. Body size comparisons are not statistically significant because of the low sample size. The N. natrix melanistic morph’s geographical distribution in the DDBR is most likely due to an interaction of climate and habitats, which offer a thermal advantage in the face of predation pressure.

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The dark side of birds: melanism—facts and fiction

Cited by 19 publications

References 30 publications

A large‐scale survey of bird plumage colour aberrations reveals a collection bias in Internet‐mined photographs

A large‐scale survey of bird plumage colour aberrations reveals a collection bias in Internet‐mined photographs

Possible mechanisms of substrate colour‐matching in larks (Alaudidae) and their taxonomic implications

Melanism in the grass snake Natrix natrix (Linnaeus, 1758) from the Danube Delta Biosphere Reserve, Romania

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The dark side of birds: melanism—facts and fiction

Cited by 19 publications

References 30 publications

A large‐scale survey of bird plumage colour aberrations reveals a collection bias in Internet‐mined photographs

A large‐scale survey of bird plumage colour aberrations reveals a collection bias in Internet‐mined photographs

Possible mechanisms of substrate colour‐matching in larks (Alaudidae) and their taxonomic implications

﻿Melanism in the grass snake Natrix natrix (Linnaeus, 1758) from the Danube Delta Biosphere Reserve, Romania

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Melanism in the grass snake Natrix natrix (Linnaeus, 1758) from the Danube Delta Biosphere Reserve, Romania