Help! G.K. Chesterton, errant wings?

[konohazuku]

Does someone know "errant wings" in Chesterton's Works?
From which Works?

[Logos]

The Donkey :

When fishes flew and forests walked
And figs grew upon thorn,
Some moment when the moon was blood
Then surely I was born;

With monstrous head and sickening cry
And ears like errant wings,
The devil's walking parody
On all four-footed things.

The tattered outlaw of the earth,
Of ancient crooked will;
Starve, scourge, deride me: I am dumb,
I keep my secret still.

Fools! For I also had my hour;
One far fierce hour and sweet:
There was a shout about my ears,
And palms before my feet.