Immanuel Kant's Sparrow

The adoption of foreign song elements occurs under natural
conditions in various songbird species including the house sparrow
Passer domesticus, even though it may go largely unnoticed by
humans. House sparrows singing canary song have been known by
hobbyists for a long time. My study is the first to analyse the
imitative abilities of house sparrows in detail. I used an
integrative approach considering features that are particularly
important for the degree of vocal learning that can be displayed by
a species. These included (1) a genetic predisposition, (2) body
condition of the parents, (3) food availability during early
ontogeny, (4) social factors, (5) neuronal mechanisms, (6) hormonal
states, and (7) body size and morphology of the vocal tract. House
sparrows singing canary-like songs provide a rich tool for further
integrative approaches. I suggest an interpretation combining all
the above features under the perspective of female choice. Instead
of searching for a „key adaptation“ or single explanation for the
imitative ability (song learning ability) in passerines, it might
be more appropriate to focus on the multiplicity of factors
involved in song production that - shaped by different selective
forces - promote the highly specific song adaptations.