"For every mavis that sings in Faoilleach, she’ll lament seven times ere spring be over."
Balanced polymorphism could arise when a predator like the Song Thrush has a given 'search image', so it tends to see and kill snails of a particular colour and pattern.
European Blackbirds and Song Thrushes (self-introduced around 1950) are also thought to be predators of the snail.
Additional factors were competition with introduced Song Thrushes and Common Blackbirds, as well as by interbreeding with the latter species producing sterile offspring.
song | Eurovision Song Contest | Song Dynasty | My Way (song) | Eurovision Song Contest 2008 | Eurovision Song Contest 2013 | Academy Award for Best Original Song | Eurovision Song Contest 2009 | Eurovision Song Contest 2006 | Song | Eurovision Song Contest 2011 | A Nightingale Sang in Berkeley Square (song) | A Song of Ice and Fire | Viña del Mar International Song Festival | Eurovision Song Contest 2004 | The Song of Hiawatha | Song of the Year | Grammy Award for Song of the Year | Dream a Little Dream of Me (song) | Eurovision Song Contest 2007 | Song of the South | Cyprus in the Eurovision Song Contest | Song of Songs | Luxembourg in the Eurovision Song Contest | I've Got You Under My Skin (song) | Eurovision Song Contest 2010 | Creep (Radiohead song) | World Popular Song Festival | Space Oddity (song) | Song Sparrow |
There are over 70 different kinds of bird, including Kingfisher, Dipper, Sparrowhawk, Kestrel, Song Thrush, Bullfinch, Grey Heron and Blackcap.