Possible Clues:

• A little bird tells one how to empty it, perhaps
• Wren, for one
• Cat gets bird - a blue one
• Cat gets bird - another bird gets both
• Popular name for a songbird
• Bird that sang 'Willow ____'
• Bird - it's essential to get it motivated, once it's recoiled
• A little bird tells me that's one way to empty it, by the sound of it
• A bird has to mount it
• There's little of it in the air to empty it, perhaps