Global changes and animal phenotypic responses: melanin-based plumage redness of scops owls increased with temperature and rainfall during the last century

The ecological effects of global climate changes
include shifts of species’ distribution and changes
inmigration strategies and phenotype. Colour polymorphism,
which can be envisaged as a species’
evolutionary response to alternating conditions or
to a wide range of habitats, may be affected by
climate changes as well. The scops owl (Otus
scops) shows two main colour morphs, dark- and
pale-reddish, as well as intermediate morphs. We
investigated temporal trends in an index of plumage
colour of Italian scops owls from museum collections
(1870–2007). We found a significant increase
in plumage redness over the last century, which
was correlated with an increase in temperature
and rainfall of the years before specimen collection.
However, the temporal increase in plumage redness
persisted after controlling for climatic variables,
suggesting that other environmental factors could
be involved. Our study indicates that ongoing
climate changes might have either shifted the selective
balance between colour morphs, or differentially
affected migration and movement patterns of
colour morphs.