Living environment and biology of the species
The Great Crested Grebe nests in a variety of aquatic habitat types, such as freshwater and brackish lakes with abundant submerged and emergent vegetation. It equally chooses eutrophic and non-acidic waters with muddy or sandy substrates and more or less steep banks. It prefers aquatic habitats with a large water surface area and depths of up to 5 m.
In winter it can be seen on wide-open lakes where the water does not freeze, and occasionally along the coast of marine habitats.
It is a generally solitary bird. Very rarely groups of more than 100 individuals can be seen. It is a very good swimmer and diver. It floats on the surface of the water or may dive, leaving only its head and neck out when it senses danger. It cannot fly from the ground, and in order to take flight from the water it must gain momentum by running on water.
Maximum longevity of 19 years. Reaches sexual maturity at age two.
Food consists of aquatic insects (mayflies, water bugs, dragonfly larvae, aquatic beetles) and small and medium-sized fish (eelgrass, juvenile carp, flounder, bass) up to 25-30 cm long. Rarely, it may consume small water snakes and amphibians. To feed, it dives from the surface of the water to depths of up to 4 m, using legs or wings for propulsion. It can stay underwater for up to 1 minute. Prey can be eaten both while diving and at the surface.
It is a monogamous species, with pairs maintaining each other during a nesting season. Sometimes, if the pair uses the same territory, they can maintain themselves for longer periods. The mating ritual is complex and fascinating. The two partners perform a dance in which they mime cleaning their feathers, vigorously shake their heads, and present their chosen nest building material. In the so-called ‘penguin dance’, the two partners rise with their whole bodies from the water, joining chest to chest. They usually nest in solitary pairs, but colonies of more than 20 nests have also been reported, with a distance between nests of 20-25 m. The nest is constructed of floating aquatic plants and is anchored by emergent vegetation. Lays 3-6 eggs in May-June, which are incubated for 21-29 days by both partners. When they leave the nest, they cover the eggs with decaying vegetation, thus maintaining temperature. The chicks hatch one at a time. They swim and dive from day one. The parents nurse their chicks until they are 10-11 weeks old. In bad weather, the chicks can be carried on the parents’ backs. In the event of danger, the parent carrying the chicks may dive with the chicks.