Hello fellow bird lovers!
My family and I are relatively new to birding...at least in a more serious way. We started getting serious at the start of the lockdown in March 2020. We go for walks almost daily by the river in Cambridge, Ontario.
Yesterday, we witnessed something quite odd and I would love to hear some thoughts and insight from more experienced birders.
We walk across a bridge to go over the river at the park. On the East side of the bridge, we noticed a group of about 8 to 10 Mallard ducks diving under the water. This wasn't the usual behavior of sticking their heads under water with their tails sticking straight up in the air. They were actually fully submerging and staying under for 5 to 10 seconds at a time. They seemed to have a special technique with their wings to thrust themselves under the water, which worked, but wasn't particularly graceful, ha! Lots of noisy splashing! I've never seen or heard of Mallards behaving this way! Another group of Mallards on the west side of the bridge were not diving at all, so they appeared to be two different distinct groups.
Thankfully, we happened to have a pair of binoculars on hand. Upon closer observation, we noticed, nearby this group of odd Mallards, a pair of Hooded Mergansers - one male and one or two females. They were diving in amongst the diving Mallards.
My theory: The Mergansers adopted the Mallards and taught them how to be diving ducks! Perhaps they came across abandoned eggs and claimed them as their own? Is that a possibility? Has anyone else ever seen diving Mallards?
-Colleen and family
Mallards can dive just not as well, as often, nor as deep as "diving ducks".
If fact I have photographed them diving in the winter time in the shallow water via a large open area we had in the ice created by a bubbler. They were diving under and coming up with large bullfrog tadpoles. They then had quite a time even swallowing the tadpoles. When one Mallard came up with a tadpole the other Mallards would chase the Mallard around trying to steal the tadpole away from it (and sometimes succeeding.) American Crows would sometimes get in on the action waiting at the edges of the open water in case a Mallard dropped a tadpole and when this happened the crow would snatch it away. Bullfrog tadpoles take a few years to turn in to a frog. That is why there were tadpoles in the pond even in the dead of winter here in Ithaca, NY where the Cornell Lab of Ornithology is located.
This is a Wonderful story! It is a normal Foraging and feeding habit for ducks to hang in large groups of different species, especially in winter. But I don't get to see Hooded mergs all that often So this was wonderful too hear! They most likely didn't adopt their eggs, but it is still a wonderful thing to think about!