Window Box Plants Disappearing: Birds, Deer, or Human Thieves?

Sister in Oklahoma City: marigolds and morning glory seedlings in window box vanish overnight—whole plants gone. No chipmunks/pack rats. Birds are sparrows. Sister's ground plants two apartments away are fine.

Possibilities (The Long Island Gardener)

• Birds: Sparrows eat sprouts. Author's Brooklyn rooftop garden lost tuberose sprouts daily to birds.
• Deer: If present, they'll eat window boxes. Morning glories not typical deer food.
• Slugs/snails: Only if imported in pots; check under pots.
• Human theft: "Greedy Gardeners" steal plants—Chicago Tribune reports organized plant theft.

Whole plant gone with roots suggests deer or humans. Birds usually leave some debris.