3. The thrush is mentioned in The White Goddess:

"Apr. 16 - May 13 - S - seg, hawk; sodath, fine-coloured. Why is the Hawk in this place? Not hard. Amergin sang of this month: 'I am a Hawk on a Cliff.' And Fine-coloured are its meadows.

The same - SS - stmolach, thrush; sorcha, bright-coloured. Why is the Thrush joined with the Hawk? Not hard. The Thrush sings his sweetest in this month. And Brightcoloured are the new leaves."

It may be a coincidence that stmolach was used at double S (there are double heads in kea). However, in the Swedish language there is a name for a species of thrush, dubbeltrast (double thrush), which is rather strange. Why should such a thrush be 'double'?

Translating its name into English makes this bird species no less peculiar - mistletoe thrush. It seems to thrive on the berries of the mistletoe.

The strange mistletoe is deeply involved in myths, for instance when the mistletoe was used as an arrow to kill Balder:

(Each arrow overshot his head. Elmer Boyd Smith. Picture from Wikipedia)

We cannot continue further in the mistletoe direction at the moment, it would take too much time and effort. Instead we should consult the bird list of Easter Island in order to look for the thrush.