Mystery Duck

While working at the Stone Zoo near Boston, my fellow coworkers and I have grown very fond of a small flock of ducks the zoo has on exhibit with their Sandhill Cranes.

Two of our "Mystery Ducks"

For a few weeks we weren’t exactly sure what species of duck they were; they were very small and covered in light and dark brown plumage. The only thing we were certain of, was that they were in the diving duck family because they were constantly diving and searching for food.  So, with our continuing interest in trying to find out what species of duck we were watching, we started our research.

Since most of us took ornithology classes in college, it wasn’t hard for us to work together and break down the steps in identifying wildlife. Since we already knew they were basically all brown and a part of the diving duck family, we needed to figure out what species of diving duck inhabited the northeastern part of the United States.

They were immature Hooded Mergansers - photo by Michaela Henneberg, World Bird Sanctuary Trainer, Stone Zoo, Boston

We only found a few species that matched the description of the ducks we were observing.  These ducks had a very broad crest that kind of looked like a fan and a serrated bill that was all black.  Their crest was so distinctive, we were able to pinpoint that we were dealing with Hooded Mergansers--the smallest of the three Merganser species occurring in North America.

Probable male - photo by Michaela Henneberg, World Bird Sanctuary Trainer, Stone Zoo, Boston

After we finally figured out we were observing Hooded Mergansers, we started noticing that some of the birds in the flock were starting to change plumage. A few weeks later we noticed that three of the birds’ eye colors were changing from brown to yellow.

Immature male Hooded Merganser

So, I continued my research and found that male Hooded Mergansers don’t reach sexual maturity until their second breeding season.  Once they reach their full adult plumage, the males will have a large white crest surrounded by black, and their neck and back will turn all black.  Also, their breast and belly becomes all white and the iris becomes bright yellow, while their feet become a dull yellow.

Mature male in breeding plumage

Female Hooded Mergansers remain a grayish brown with a reddish-brown crest, and their upper bill is black-edged with a mix of orange, while their lower bill is yellow.  Unlike the males, the females’ legs and feet are greenish in color and their iris remains brown.

Probable female - photo by Michaela Henneberg, World Bird Sanctuary Trainer, Stone Zoo, Boston

All in all, we have determined that three out of the six ducks we have been observing will be males for next year’s breeding season and they will be a beautiful sight for families to see.

Submitted by Josh Kuszmaul, World Bird Sanctuary Stone Zoo Assistant Supervisor