I'll chime in here if allowed..
Ducks can do ramps very well but training is needed and realistic ramps provided...

Ducks can do ramps very well but training is needed and realistic ramps provided...

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That looks pretty good to me. Not too terribly steep but I would put some small strips of wood going horizontally about every foot all the way up the ramp for traction. If you could put a solid board between the base of the structure and the ramp on the left it might make them feel more secure about not falling off.