P W Joyce's 'Old Irish Folk Music and Songs' (1909) gives this: (with musical notation)

THE BLACKBIRD

On a fair summer's morning of soft recreation,
I heard a fair lady a-making great moan;
With sighing and sobbing and sad lamentation,
A-saying "My Blackbird most royal is flown.
My thoughts they deceive me, reflections do grieve me,
And I am o'erburdened with sad misery;
Yet if death it should blind me as true love inclines me
My Blackbird I'd seek out wherever he be.

Once in fair England my Blackbird did flourish,
He was the chief flower that in it did spring;
Prime ladies of honour his person did nourish,
Because that he was the true son of a king.
But this false fortune, Which still is uncertain,
Has caused this parting between him and me.
His name I'll advance, In Spain and in France;
And I'll seek out my Blackbird wherever he be.

The birds of the forest they all met together-
The Turtle was chosen to dwell with the Dove:
And I am resolved in fair or foul weather,
In winter or in spring, for to seek out my love.
He is all my heart's treasure, My joy and my pleasure,
And justly, my love, my heart shall follow thee;
He is constant and kind, and courageous of mind;
All bliss to my Blackbird wherever he be.

In England my Blackbird and I were together,
Where he was still noble and generous of heart;
And woe to the time that he first went from hither,
Alas, he was forced from thence to depart;
In Scotland he is deemed and highly esteemed;
In England he seemed a stranger to be;
Yet his name shall remain in France and in Spain;
All bliss to my Blackbird wherever he be.

It is not the ocean can fright me with danger;
For though like a pilgrim I wander forlorn,
I may still meet with friendship from one that's a stranger
Much more than from one that in England was born.
Oh, Heaven, so spacious, to Britain be gracious,
Tho' some there be odious both to him and me;
Yet joy and renown and laurel shall crown
My Blackbird with honour wherever he be.

It's number 376, p. 181.
He says:

In the early half of the last century this song was known and sung all over Ireland. It was particularly favourite in Limerick and Cork, so that I learned it at a period too early for me to remember.
An abridged copy of the song is given in Duffy's Ballad Poetry: but I give here the whole text, partly from memory, and partly from a ballad-sheet printed in Cork by Haly, sixty or seventy years ago. Duffy tells us that the song - i.e. the curtailed copy he has given - is found in a Scotch collection of Jacobite Relics. But the words are Irish - as much so as the splendid air, which is found in many Irish musical collections, both printed and MS., including Bunting's volume (1840), and which was, and still is, played everywhere by Irish pipers and fiddlers. My notation of the air follows the Munster musicians and singers of sixty years ago.
The "Blackbird" meant the Young Pretender, Prince Charles Edward Stuart. This custom of representing the Pretender - and much oftener Ireland itself - under allegorical names was common in Ireland in the eighteenth and the first half of the nineteenth century; the original object of which was concealment, so that the people might be able to sing their favourite Jacobite and political songs freely in the dangerous times of the Penal Laws.