Colour aberrations in Eurasian Magpies Pica pica in Europe

Information about the relative frequency and geographical variation of colour aberrations in birds is rare. By entering the word Magpie Pica pica in 37 European languages into an Internet search engine, I was able to trace 3,974 photographs in 2015 and 3,672 photographs in 2016 in more than 40 countries. By analysing the photographs, I found a significant difference in the frequency of aberrant Magpies, with the frequency increasing northwards and decreasing eastwards. Leucism was the most common aberration, followed by brown (brown and ino) and dilute. Despite some changes in the number of Magpie pictures found for each language between the two years, the numbers correlated strongly. The percentage of aberrant Magpies found for each language in 2015 correlated significantly with the percentage in 2016. While using pictures obtained from the Internet has inherent biases and limitations, it is also a useful new tool revealing patterns in geographical variation in aberrant colouration in several bird species, and allowing us, eventually, to understand the differences.