John Thompson sings a version of Three Crows on his Australian folk song a day blog:

http://ozfolksongaday.blogspot.co.uk/2011/11/three-crows.html

Apparently collected by Wendy Lowenstein in November, 1969 from Dave Guard, "an old resident of Georgetown, Queensland".

Now three black crows sat on a tree,
As black as any crows could be
Caw, caw, caw.

Said one black crow unto the other
"Where shall we dine today dear brother?"

"On yonder hill's an old grey mare.
I think my friends we shall dine there".

They perched upon her high backbone,
And picked her eyes out one by one.

Said the second black crow unto the other,
"Isn't she a tough old bugger"

Up come a squatter with his gun,
And shot them all excepting one.

Now that one black crow got such a fright,
He turned from black right into white.

Now that is why you'll often see
A white crow among the tree.