Although strawberries are not a natural part of a duck’s primary diet, they can eat them on occasion without any serious health risks. There is no doubt whatsoever that strawberries are extremely nutritious and have many health benefits for both humans and animals alike, so it will be okay to give your ducks small strawberries slices once in a while.
It will be important to keep in mind that you should not give too much at one time though, because they have a very delicate digestion process which cannot be interrupted by any means. If you feel the need to give your ducks strawberries, you should do so in moderation.