SPOONERISMS XVI

A Spoonerism is a phrase in which the initial letters or sounds have been reversed.
For example: Hate the book - Bait the hook.

In the flat below, the key words ONE and TWO can be answered by Spoonerisms:

Many sounds at the lake
When the sun is shining strong;
Quacking ducks, croaking frogs,
Lots of birds - hear their song.

Then, at night, the sun has set;
Silence hangs over all.
But, by ONE, if we listen,
A TWO may give its eerie call.

Answer:

But, by MOONLIGHT, if we listen,
          A LOON MIGHT may give its eerie call.

Credit: 
The Enigma 
NPL Magazine
September, 2019
A. CHEMEM