1 research outputs found
Factors associated with leucism in the common blackbird Turdus merula
Leucism is the total or partial lack of melanins in the skin and associate structures
(i.e. hair or feathers). Little is known about the factors influencing this chromatic
aberration although some local studies suggest that there is an effect of habitat, age and
sex. To test these hypotheses and expand our knowledge on leucism, we carried out a
large-scale study using common blackbirds Turdus merula as our model species. Given
the poor information available on this topic and the variability of methodological
approaches, we used three different methods to assess the effect of these variables
in the presence of leucism: transects, bird captures and citizen science information
(pictures from internet). We found an effect of habitat indicating that there are more
leucistic blackbirds in cities than in non-urban areas. In addition, we found a positive
association between presence of white feathers and age providing the first large-scale
support for the progressive graying hypothesis in birds. This chromatic aberration was
also influenced by sex, with males showing higher probability of leucism than females,
although only for the capture data, indicating that the method used to study this
phenomenon can partly influence our conclusions, and therefore suggesting caution
when planning future studies in this topic.JDI was funded by a postdoctoral contract (TAHUB-
104) from the program âAndalucĂa Talent Hubâ (co-funded by the
Europeanâs Union Seventh Framework Program Marie SkĹodowska-
Curie actions â COFUND â and the regional Government of
AndalucĂa). ADF was funded by a Severo Ochoa grant (SVP-2014-
068571) from MICINN (Spain)