Moonspear Fire may save you

"Like this," Ness prompted, stamping her foot down so it made a clear pawprint in the earth, then using one of her toes, scratched a line upwards from the indention— a representation of the bottle's neck. "They'd fall in through here," she motioned with her foot down the drawing's tube; "and then this part," her foot circled the pawprint; "is where they'd be trapped. See?" She looked up, wondering if Firebird was picking up on her general idea. "It would make the sides round, wider than the opening, and the bottommost point of the trap would be too deep to jump straight out of."

She took a breath, though the over-confident Ness never quite felt as if she was being too wordy. The girl hadn't a shred of self-consciousness. "I just think it'd be kinda harder for them to get out, if they had this bowl down there— all that space— and an opening that was only big enough for them to fall through. Come to think of it, I wonder if this would work for a predator. Y'know. A big enough one? How high can coogs jump anyway?" she asked offhandedly.