Nightingale Wake Up Call

Listen to the nightingales singing,
Their voices echoing through the night,
Their songs of gratitude still ringing,
As they greet the morning's first light.

Their voices echoing through the night,
Proclaiming the arrival of dawn,
As they greet the morning's first light,
Which elicits from humans a yawn.

Proclaiming the arrival of dawn,
The sparrows join the nightingales choir,
Which elicits from humans a yawn,
And causes them to don work attire.

Line Count: 12
Form: Pantoum composed of quatrain stanzas rhyming A1, B1, A2, B2, ... B1, C1, B2, C2, etc. http://www.thepoetsgarret.com/2012Challenge/form20.html
Written for "Invalid Item"  round 32