10 Ruddy Duck Facts Every Waterfowl Enthusiast Should Know

Some duck species stand out more than others and are especially memorable to birders because of their unique looks or behaviors. The Ruddy Duck is one of those species, well known for both its appearance and its unusual behaviors. It is often called the “clown of the wetlands” because of its quirky courtship displays, especially the bubbling behavior made by males. Ruddy ducks also stand out, thanks to their blue bills and long, stiff tails, which they often hold upright. Below are more fascinating fun facts you probably didn’t know about ruddy ducks.

1. THEY ARE STIFF-TAILED DUCKS

Ruddy duck is one of the six duck species often referred to as stiff-tailed ducks (genus Oxyura). As the name suggests, stiff-tailed ducks have long, stiff tails that they often hold upright, especially when floating on the water.

2. THEY ARE NICKNAMED “BUTTERBALLS”

Besides the “clown of the wetlands” nickname, birders sometimes also call them “butterballs” because of their short, round, chunky body shape. Their body looks a bit puffed up, which can make flying and even walking seem awkward.

3. STRIKING SKY-BLUE BILLS IN BREEDING MALES

One of the most eye-catching features of ruddy ducks is their bright sky-blue bill, a rare feature among duck species. It becomes especially noticeable in breeding males, where it contrasts sharply with the rich chestnut body, white cheeks, and dark cap. Even at a distance, that flash of blue can be enough to pick them out on the water.

4. THEY DON’T FLY MUCH

Compared to many ducks, ruddy ducks rarely fly. But when they do take off, they need a running start and fly low with very fast wingbeats.

5. THEY LAY THE LARGEST EGGS

Ruddy ducks lay the largest eggs of any duck relative to their body size. Despite them being medium-sized ducks, measuring 34–43cm (or 13.5–17 in) in body length and weighing about 560 g (1.23 lb), their eggs are remarkably large, measuring about 5.9-6.8 cm. The eggs are white with a rough, pebbly texture and require a lot of energy to produce.

6. THE FAMOUS “BUBBLING” COURTSHIP DISPLAY

Breeding male ruddy ducks are well known for their unusual courtship display called “bubbling.” Instead of relying on loud calls or quacking, males beat their lower bill against their chest in a fast drumming motion. This creates a soft, rhythmic sound, and it is often strong enough to send small swirls of bubbles rising in the water. It’s one of the most distinctive breeding behaviours in ducks and gives the species much of its “clown of the wetlands” reputation.

7. THEY PRACTISE BROOD PARASITISM

Some female ruddy ducks show a behavior known as brood parasitism, where they lay their eggs in the nests of other females instead of raising them themselves. The exact reason for this is still not fully understood, and no single clear factor explains why it happens. Interestingly, studies have found that these parasitic eggs are more likely to produce male ducklings than females. Some researchers also suggest it may be linked to a mismatch between the female’s breeding timing and environmental cues.

8. THEY ARE CONSIDERED INVASIVE IN SOME REGIONS

Outside their native range in the Americas, ruddy ducks are regarded as an invasive species in certain regions. In Europe, for example, they have been included since 2016 on the list of Invasive Alien Species of Union concern. This means they are strictly controlled and cannot be imported, bred, transported, sold, or released into the wild across the European Union. Because of their potential impact on native waterfowl, some countries have also carried out control or culling programmes to reduce their numbers.

9. TACTILE FEEDING AND SMART FORAGING

Since Ruddy ducks mostly feed underwater in cloudy, stirred-up water, they rely on touch rather than sight to find food. Their bills have sensitive nerve endings that help them detect small larvae, molluscs, crustaceans, and plant material even in moving water. They also tend to return to spots where they previously found food, showing a simple but effective way of remembering productive feeding areas.

10. THEY FACE ATTACKS FROM OTHER WATER BIRDS DURING BREEDING

During the breeding season, ruddy ducks get harassed by birds like grebes and coots. Some grebes even attack from below the water in a behavior known as “submarining.”