Ring-necked ducks (Aythya collaris) are medium-sized divers that can sometimes be spotted in our area. Males are dark with a whitish underside. Females are grayish brown. Both have a white band across the bill and yellow eyes. Despite their name, you will not be able to see the brown ring around the neck of a breeding male – in the 1800s, when naturalists came up with the name, it was by examining dead birds – and this is really the only time a person can see the neck ring, and only by being very close. Perhaps ring-billed duck would have been a better name, since you can see a white band around the bill from a good distance.
These ducks are migratory and live during breeding season in Canada and the northern areas of the United States. From September to December, they go south. Some spend their winters in Southern New England’s freshwater wetlands. In February or March, they return north again.
Although these ducks are good divers, they often prefer to eat submerged plants near the water’s surface. These ducks are omnivorous, with breeding females and young birds eating more animal matter such as insects, worms, leeches and dragonflies. They also feed on snails and clams, which they swallow whole, crushing the shells in their gizzards. Males and nonbreeding females eat a more plant-based diet, including roots, tubers, seeds, grains, wild rice, sedges and lily pads.
These ducks are more commonly seen today than they were in the 1800s. William Brewster called them a “very rare transient visitor in autumn.” He writes of a time he saw one:
Shortly after sunrise on the morning of November 26, 1867, I noticed a solitary Duck in Smith’s Pond, diving for food near the eastern shore. By advancing quickly when it was under water, and flattening myself on the open, marshy ground just before it came to the surface, I approached within easy gun-range and killed the bird, which proved to be a young male Ring-neck. The specimen is still preserved in my collection.
No wonder these ducks were rare transient visitors.
Did you know that female ducks, like most birds, have only one functioning ovary (the left one)? The reason for this is not clear. Some scientists think this feature evolved to help birds fly better, as the less they weigh, the better they can fly. Others think that it has more to do with the stability and durability of the egg’s shell.
In birds and mammals, chromosomes dictate sex. Human females have two X chromosomes and males have an X and a Y. The male determines the sex of the offspring. Birds are different: The sex chromosomes in birds (and butterflies and lizards) are Z and W. Males have two Z chromosomes and females have one Z and one W. The female determines the sex of the offspring. ZZ embryos develop into male ducks. ZW embryos develop into female ducks.
The duck’s ovary is where egg production begins. The oviduct (called fallopian tubes in humans) connects the ovary to the uterus. In the ovary, the yolk grows. When it is large enough, it is released to begin its 24-hour journey to becoming an egg. This process is like an assembly line. First, the yolk spends 15 minutes just outside the ovary waiting to be fertilized. When the time is up it moves on, whether it is fertilized or not.
From there the yolk spends about three hours while albumen (egg white) is deposited over it. Next, a membrane coats the albumen. This membrane gives the egg its shape and holds it together (and you thought the shell did that). Finally, the egg enters the shell gland (uterus), where it spends about 20 hours. This gland secretes calcium carbonate over the membrane, which hardens to form the eggshell. The shell protects the developing egg from bacteria. It also has microscopic pores that allow gases to be exchanged. In the final hours, colored pigments are deposited onto the eggshell as it rotates.
At last, the egg is ready for the female to lay it! When the egg traveled down the oviduct, it went small end first. But now the egg rotates, so that the large end is first. The uterus contracts to push the egg out of the female’s body.
When the egg is first laid, the embryo fills the entire shell. But the duck’s body temperature is about 106 degrees Fahrenheit. The air temperature is much cooler, so the embryo contracts inside the shell and an air pocket forms. About a month later, when the chick is ready to hatch, it punctures the membrane around this air pocket so it can breathe until it is able to crack open the shell. The air pocket provides enough air for a few hours.
The chick uses its egg tooth (a sharp projection on the end of its bill) to puncture the shell. It rotates its body inside the shell until it has cut the shell all the way around. It then pushes off the end of the shell to hatch. The egg tooth disappears in a few weeks.
After the chicks hatch, the female ring-necked duck protects them and keeps them warm, but she does not feed them. The ducklings find food for themselves and can dive within two days. Because these birds do not breed in our area, you will not see young ring-necked ducks around here, but this is the time of year you might see the adults waiting out the cold weather so they can return to their northern breeding grounds.
Have you taken photos of our urban wild things? Send your images to Cambridge Day and we may use them as part of a future feature. Include the photographer’s name and the general location where the photo was taken.
Jeanine Farley is an educational writer who has lived in the Boston area for more than 30 years. She enjoys taking photos of our urban wild things.
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