I could not find the lyrics to "Where Two Hawks Fly" anywhere on the web, except the possibility of buying The Corries songbook from England. . . so I just listened to the song over and over (I think it's beautiful), and here's what I came up with. I think I got most of it right, except for the first word in the line about the feasting board:

I walk alone where two hawks fly
Where once was heard the bairnie's cry
Where water runs in the rankle burn
On the broken bridge grows green among the fern

The lonely heron stands gray and still
The silent guardian o'er the hill
His watch is shared by the tombstone tall
Ancient music echoes in the crumblin' wall

The harp, the flute, the pipe and drum
Are signal for them all to come
To lay aside the spear and bow
On? the feasting board where wine and laughter flow

What castle then, what castle now?
The farmer stands, commands the view
The crescent moon hangs above the door
And the spirits softly tread the kitchen floor . . .

Also, here's a note about the song that went along with Corries album notes from somewhere:
WHERE TWO HAWKS FLY*
Roy: Northumbrian Pipes
Ronnie: Vocal
The subject of the song is in the Scottish border country, a farmhouse standing on the site of an ancient fortress of the Buccleuch family. The castle was once the centre of a thriving community, but all that remains today is the keystone of the original archway and part of the family crest set in stone, "... the crescent moon", referred to in the song.