Colour Aberrations in Eurasian Magpies Pica pica in Europe

“Some exhibit a higher proportion of light morphs in the north, such as the Gyrfalcon Falco rusticolus (Cramp & Simmons 1980) and Arctic Skua Stercorarius parasiticus (Cramp & Simmons 1983).”

“Magpies lack carotenoid colours (Prum 2006), so variations in the black parts of their plumage should be easy to detect.”

“The most common pigments are carotenoids and melanins (Andersson & Prager 2006).”

“In addition, increased frequencies of colour aberrations in birds might occur in areas with increased radioactivity (Møller & Mousseau 2001), or as a result of recessive genes more often being expressed in small inbreeding populations (Bensch et al. 2000).”

“Melanin pigments are responsible for the black colouration of feathers (McGraw 2006), and aberrations in the black colouration are often the easiest to detect.”

“In addition, increased frequencies of colour aberrations in birds might occur in areas with increased radioactivity (Møller & Mousseau 2001), or as a result of recessive genes more often being expressed in small inbreeding populations (Bensch et al. 2000).”

“No melanin is produced, and the entire bird, including the eyes, beak and legs, lacks the melanin colours (Fox & Vevers 1960; van Grouw 2006).”

“Colour aberrations have been recorded in 54 of the 75 families of North American birds (Gross 1965), and 42 of 59 bird families in Britain (Sage 1963).”

“Several of these aberrant colour forms are mentioned in the literature about Magpies (Linsdale 1937; Coombs 1978; Birkhead 1991).”

“This seems logical, as an earlier investigation found that iridescence only occurs in the dark feathers of Magpies (Vigneron et al. 2006).”

“In the first, Owen and Shimmings (1992) showed that Barnacle Geese Branta leucopsis vary in the frequency of leucism in different populations.”

“In addition, Magpies are often conspicuous with their contrasting black and white plumage and therefore easy for a goshawk or other raptors to find (Götmark 1997).”

“However, phaeomelanin might also be involved in the production of black colours (Galván et al. 2015).”

“This pattern is far from consistent, and crypsis, predation risk and temperature balance are probably important factors responsible for this variation (Itoh 1991).”

“Several of these aberrant colour forms are mentioned in the literature about Magpies (Linsdale 1937; Coombs 1978; Birkhead 1991).”

“bird images available on the internet) (Husby 2017).”

“However, we caution the use of com-munity-gathered data as individuals may be more inclined to report individuals with charismatic coloration compared to those of regular coloration (Husby, 2017; Zbyryt et al., 2021; Carlen et al. 2024).”

“In another corvid, such as Eurasian Magpie Pica pica, the percentage of individuals with colour aberration was 0.9% in 2015 and 1.1% in 2016 (Husby 2017).”

“…equipment, the expansion of bird-watching groups, and the development and application of the internet, more and more birds with color aberrations are being discovered and reported (Husby, 2017; Mahabal et al., 2016; Ray, 2021; Tinajero & Rodríguez-Estrella, 2010; Zbyryt et al., 2021 ).”