Two mallard hens nesting at the base of a tree.

Sometimes ducks and geese do interesting things during the breeding season. I have seen Canada goose nests high in trees, on the roof of a building and on rock cliffs above the Missouri River and mallard nests in flowerbeds, on boat docks and even in boats. Many of these unusual occurrences could be attributed to domestic or feral mallard’s however; sometimes even wild waterfowl make some interesting decisions.

Our own Sandi Beitzel, DU Senior Vice-President from Manitowoc, Wisconsin, passed the following pictures of a rare occurrence in waterfowl. She found two hen mallards nesting side by side at the base of a tree.

A close-up of the nesting pair.

Generally a mallard hen and drake’s territorial behavior would preclude another hen of the same species from nesting so closely. However, such behavior is not unheard of in waterfowl. While conducting research on the nesting ecology of Missouri giant Canada geese in 1997 fellow graduate student colleague John Coluccy (now a Manager of Conservation for DU in our Great Lakes Regional Office) and I came across two Canada goose females nesting together in one nest-tub.

We had observed an apparent incident of polygynous behavior in Giant Canada Geese (Branta canadensis maxima).

Polygyny: is defined as one male pairing, mating and raising young with several females.

The two females were paired with the same male and concurrently incubated side by side within the same nest tub. This behavior was observed at the same location in two successive years and goslings successfully hatched from both nests each year. Until that time polygynous behavior in typically monogamous Canada Geese had rarely been observed, and nest sharing had not been previously documented. We documented the case in the technical journal article below.

Checkett, J. M., Coluccy, J. M., and Drobney, R. D. (2001) Polygyny in Canada Geese: An unusual example of nest sharing. Wilson Bulletin, 113, 109-110.

By complete coincidence, this weekend I noted another case of interesting if not wacky waterfowl nesting behavior at the Memphis zoo. This was a case of nest site selection. While looking into the gorilla habitat we noticed movement within a bush inside the enclosure. As I focused my camera I noted that it was a mallard hen incubating a nest!

If you look close you can see her head and bill.

This was certainly one of the more interesting choices of a nesting location that I have ever witnessed. Surprisingly the Gorilla had not noticed this nesting mallard or had not taken an interest. I left pondering how far along she was in incubation and the chance of nest success.

The mallard nest is indicated by the yellow arrow. Note the male gorilla to the left.

DU’s nesting research in North Dakota has indicated that nest success is often higher in plots that also contain raptor nests. The assumption is that these hawks, harriers and owls keep ground nest predators (like ground squirrels, opossum, skunks etc.) away.

I had to laugh and think that if she survives the gorilla she will not have to worry about other more typical duck nest predators!

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