Smew Diet and Size: Feeding Habits, Predators, and Measurements

While usually quiet, smews become more vocal during the breeding season or when displaying. The male smew gives a distinct, ascending series of rattling clicks, often said to resemble a frog’s sound. Additionally, they make a variety of grunting noises. When alarmed, their call is a rough “Kraaa.”

This vocal behaviour is regularly seen in smews, most notably during courtship, where sound plays a significant role in the communication between males and females.

Keep reading to learn not only their vocal talents but also how these ducks feed, breed, and navigate the threats in their environment.

The Dietary Habits Of The Smew

Let’s look at what a Smew eats and how their diet changes from summer to winter, along with what they feed their young.

What Does A Smew Eat?

The diet of a Smew is mostly fish, which they hunt by diving under the water and grabbing with their serrated, hooked bills, well-suited for gripping slippery prey.

Besides fish, smews also feed on aquatic insects, larvae, and small invertebrates, especially during the summer when these are easier to find.

During winter, their diet largely consists of fish, but they may turn to crustaceans like shrimp or crayfish, based on what’s within reach.

What To Feed A Baby Smew? 

Adult Smews typically provide their chicks with small aquatic invertebrates, particularly insect larvae, during the early stages of their lives. Dragonfly and caddisfly larvae are commonly fed to the ducklings. This diet supports rapid growth and supplies the essential nutrients required for their initial development.

In the first few weeks after hatching, it is the female smew who takes charge of feeding her young. As the chicks grow, they may gradually begin to eat a broader range of water insects and, eventually, small fish as they get better at hunting for food by themselves.

Breeding Habits Of Smews

The breeding habits of smews are distinctly influenced by their habitat and the changing seasons. These ducks tend to breed in the northern taiga forests across Europe and Asia, preferring to nest within tree cavities, frequently taking over old woodpecker holes.

The breeding season generally starts in May, but in the southern parts, it can begin as early as late March, whereas in the northern regions, it might be delayed until June.

Upon hatching, the ducklings are precocial, which means they are fairly well-developed and can move about right from the start. They leave the nest shortly after and are capable of flying within approximately 10 weeks.

Males are not involved in raising the young; they generally leave the breeding area before the eggs hatch to undergo moulting. The nests are often located at least 10 metres off the ground, and smews may opt to reuse nests from previous years.

Do Smews Mate For Life?

Smews don’t stay with the same mate for life. Rather, they are seasonally monogamous, which means they form pairs during the winter or while migrating. These bonds last only for a single breeding season with their bond lasting until the female is well into incubating her eggs.

After this point, the males often leave the breeding site to undergo moulting and do not contribute to rearing the young. This type of seasonal monogamy permits smews to find new mates each year, a common approach among many bird species that do not maintain lasting pair bonds.

The Size & Weight Of Smews

Let’s take a look at the physical characteristics of Smews, including both their weight and their size.

How Much Does A Smew Weigh?

Typically classified as medium-sized ducks, adult Smews have an average weight that falls between 500 and 800 grams. Nevertheless, their weight may vary due to factors like sex, individual health, and the season.

How Big Is A Smew?

Measuring between 38 and 44 cm in length (around 15 to 17 inches) with a wingspan of 55 to 69 cm (approximately 21 to 27 inches), the Smew is a compact diving duck. This modest size, and its light build, places the smew among the smaller species in the sawbill family, a group known for their fish-eating habits.

Are Smews Under Threat?

Despite being classified as a species of “Least Concern” on the IUCN Red List, Smews are still regarded as threatened. There are significant pressures on their populations in some regions.

In the UK, smews have been added to the Red List of Birds of Conservation Concern due to a notable decline in their population, which saw a 66% reduction between 1993 and 2018. This decrease is mainly driven by habitat loss and degradation, as well as increased predation by animals such as the American mink. Additionally, the effects of climate change and human-related activities, like hunting and pollution, are further contributing to their declining numbers across parts of Europe.

What Eats A Smew?

Smews face numerous natural predators within their habitats. Predators like merlins, peregrine falcons, hen harriers, and buzzards, whether rough-legged or long-legged, as well as American mink, are among the most significant. These hunters excel at preying on smews, due to the birds’ relatively petite size and their habitats, which frequently situate them near these raptors and mammals.

Where Can I See Smews In The UK?

Smews are known to visit the UK in winter, typically making their way from Scandinavia and Russia between December and March. You can catch sight of these eye-catching ducks in several regions across the country, with some of the best locations being along the coastlines of the Severn Estuary and Lincolnshire.

These areas provide the wide, undisturbed waters that smews prefer, allowing them a serene place to feed and rest while they stay. Even though smews are not commonly found, these spots offer the opportunities for birdwatchers to glimpse them during the winter period.

SEE ALSO: Smew Life Cycle: Nest Building To Fledging (and everything in between)

Frequently Asked Questions