Fabricate Birdcall (3.5e Spell)

The touched object begins tweeting like a bird, easily audible up to 60 feet away. It passively observes its surroundings, detecting anything that could be detected with a Spot or Listen check of 10 + twice your caster level. Whenever it detects a creature that it did not observe at the time of its creation, it stops tweeting for 1 round.

You may choose to specify minimum and maximum sizes for creatures that cause it to stop tweeting.

The constant tweeting generally makes creatures who are not used to it take about 1 extra hour to get to sleep, but creatures who fell asleep to the sound of its tweeting are immediately awakened when it stops.