Given that these animals can't eat each other, aren't these examples of starvation?
Both of them want to eat eat other but neither can make progress, so deadlock I think
In order to proof deadlock, you must have the 4 deadlock conditions.
2 Resources here I think: Frog's freedom + Goose's neck
Mutual exclusion: Either the frog is free to leave or the goose tries to eat it. Either the goose has its neck unobstructed or the frog grabs it.
Hold and Wait: Each one grabs each other's resource and refuse to let go.
No pre-emption: It is not possible for one to steal that resource from another.
Cyclic dependency: Goose cannot proceed until frog release goose's neck. Frog cannot proceed until goose stop eating the frog.
This is just too real and scary.