Name: Jim K.
We have a water garden (pond) in our front yard, which is too often
visited by mallards. The population of small Koi (3"-4"), initially
stocked at the beginning of May, has suddenly decreased sharply.
Hmmmm!? The residential expert (wife) doesn't believe that a duck's
menu just might include small fish! I need an expert opinion, please.
Mallards generally eat small plants and invertebrates. Some ducks,
mergansers for example, eat fish, even much larger than 3-4" but I do not
believe mallards would eat anything that size.
Ducks do not eat fish. However, chances are you're getting occasional visits
from egrets or herons, which just love koi ponds (they think of them as
sushi bars). They do not have to be there long to really clean you out.
Richard E. Barrans Jr., Ph.D.
PG Research Foundation, Darien, Illinois
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Update: June 2012