This isn't a bug, per se, but an incorrect parameter: Baby turtles can jump over fences.
Given that turtles are not known for their leaping ability, having them able to jump higher than rabbits is probably not what they're supposed to be set at.
Comments 2
Cleaning up old tickets: This ticket had been set to 'awaiting response', but has not received a response from the reporter (~6 months+) so is being closed as Cannot Reproduce. If you feel this is still a valid issue then please comment, or create a new ticket following the Issue Guidelines.
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Are you sure they're not climbing out over another block, such as more turtle eggs? Can you please add a video or screenshots of the setup?