More that 20 years ago I believe that I taped it off of Mike Flynn's "A Folk Sampler". It was sung to the tune of "Arkansas Traveler". I mostly remember the first verse, but none of the others, nor the writer...

Once I had a duck and I called him "Earl"
I later found out that Earl was a girl
But it didn't seem to matter to the duck at all
'Cause Earl would always come to me whenever I would call

Chorus (B part of the fiddle tune "Arkansas Traveler")

I gave my duck a shelter from the wind and rain
She slept in my barn, she fed on my grain
You may say that ducks are silly and they have no sense at all
But Earl would always come to me whenever I would call.

The next verse, the writer gets a duck friend for Earl, gives it a girl's name and, of course, soon finds out that this duck is male. The last verse is a barnyard full of ducks.

Anyone remember it?