Slavonian Grebe Diet and Size: Feeding Habits, Predators, and Measurements

There are only an estimated 50 or so breeding pairs of Slavonian Grebes resident in the UK. They are to be found in a few Scottish sea lochs during the breeding season. Later on in the year, the number of Slavonian Grebes increases as many fly in from northern Europe.

They can then be spotted almost anywhere off the eastern coasts of England and Scotland. They can also sometimes be spotted on large lakes and reservoirs.

In this article we’ll take a close look at the dietary habits, the breeding habits and the conservation status of these diving ducks and much more besides. Keep reading to find out more.

The Dietary Habits Of The Slavonian Grebe

Slavonian Grebes, or Horned Grebes as they are known in the US, forage by diving underwater and catching their prey either on the bottom or in open water.

What Does A Slavonian Grebe Eat?

The Slavonian Grebe has a varied diet which consists mainly of aquatic insects like beetles and water bugs. They also feed on small fish, crustaceans, molluscs and small amphibians like frogs and tadpoles.

Slavonian Grebes eat their own feathers which form a plug in their stomach that acts as a filter. This feather plug holds onto fish bones until they are digested.

They typically feed in small groups of up to 5 birds or in many cases the Slavonian Grebe is a solitary feeder.

What To Feed A Baby Slavonian Grebe? 

When feeding their chicks, Slavonian Grebes typically offer them a diet of small aquatic invertebrates like insects and crustaceans. 

As the chicks grow, their  parents introduce larger prey, such as small fish and other larger invertebrates, to match the chicks’ developing abilities to handle bigger food items. Once small fish are added to their diet, the chicks are also fed feathers taken from their parents’ bodies.

These feathers are there to do the same job in the chicks stomachs as they do in the parents, hold onto fish bones until they can be digested.

Breeding Habits Of Slavonian Grebes

Slavonian Grebes engage in highly synchronised courtship displays which include; head shaking where both males and females swim toward each other while shaking their heads from side to side. 

They also take part in what’s known as a “weed ceremony”. During this ritual, both birds dive and come up holding pieces of aquatic vegetation in their bills, which they offer to one another.

Another ritual that Slavonian Grebes take part in is where the pair will rise out of the water and run across its surface, side by side, in a display of unity and strength.

These displays help solidify pair bonds and establish mutual readiness for breeding. Once the pair bond is formed through these displays, they work closely together throughout the breeding season, including nest-building, incubation, and chick-rearing.

Do Slavonian Grebes Mate For Life?

Whilst Slavonian Grebes do not mate for life, they do form seasonal monogamous partnerships. This means they stay together with the same partner for the duration of the breeding season.

The following year, both partners will form a new seasonal monogamous partnership with different partners.

The Size & Weight Of Slavonian Grebes

Slavonian Grebes are roughly the same size as Moorhens. Like many birds, the male is slightly larger than the female and has brighter, more vibrant colourations.

How Much Does A Slavonian Grebe Weigh?

The average weight of an adult Slavonian Grebe can range from 360 to 450 grams. Their weight can vary depending on the time of year; breeding females will typically weigh more when carrying eggs.

Plus these birds will often gain weight prior to their migration period.

How Big Is A Slavonian Grebe?

The average overall length of the Slavonian Grebe is around 31 to 38 cm with a wingspan of around 59 to 65 cm. This is very similar to the size of the Moorhen.

Are Slavonian Grebes Under Threat?

Slavonian Grebes are under some threat, particularly due to habitat loss and environmental changes, although they are currently listed as a species of Least Concern by the IUCN. Their population trends, however, show declines in certain regions.

They face problems due to habitat loss from wetland drainage, agricultural expansion and human disturbance due to development and recreational activities close to breeding sites. Water pollution is another problem which can be caused by oil spills as well as chemical runoff.

Changing weather patterns like droughts or changes in seasonal water levels can affect their breeding areas. They also fall foul to fishing nets getting caught up and then drowning.

What Eats A Slavonian Grebe?

They also face the threat of predators like Peregrine Falcons and Goshawks that often take adult Slavonian Grebes from open water. Other birds like Herring Gulls, Crows and Ravens will all take eggs and chicks from nests.

Other predators include mink, rats and other mammals which will also raid nests. In some cases, large fish like Pike will take young chicks when they’re swimming on open water.

Where Can I See Slavonian Grebes In The UK?

Slavonian Grebes can be seen in different locations in the UK depending on the time of year;

During The Breeding Season

• The Scottish Highlands
• Loch Ruthven

During The Wintering Season

• The Moray Firth (northeast Scotland)
• The Firth of Forth (southeast Scotland)
• The Clyde Estuary (west Scotland)
• The North Norfolk Coast (England)
• The Solent (between Hampshire and the Isle of Wight)
• Swansea Bay (Wales)
• Carmarthen Bay (Wales)

In winter, the grebes are often found in small groups, and their distinctive white and black plumage (winter colours) makes them easier to spot. Scotland is still the primary region for both breeding and wintering Slavonian Grebes in the UK.

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

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