Great Crested Grebes show some variability in their head moult and in February a range of plumages from full winter to full breeding can be seen, so the three individuals were likely adults in different stages of their moult.
Changes in the plumage of the head. The plumage types of individual grebes in relation to date are
given (males = filled and females = open symbols). Dots refer to scores based on examining photographs of grebe-heads, whereas the triangles indicate the results of examining museum-skins. (from Piersma, 1988)
Winter plumage individual on agressive posture, a few crest feathers and the dark tips of the tippets have already emerged.
Breeding plumage individual preening its back feathers
It appeared to try and grab the attention from the winter plumage individual, and...
...got very close.
But it got the wrong sort of attention, as the winter plumage individual threatened it
the summer plumage individual flies away.
The two winter plumaged individuals close to each other, watched by the breeding plumage one
A couple of short videos on the interactions between the two individuals.
More informationTheunis Piersma (1988). The annual molt cycle of Great Crested Grebes. Ardea, 76, 82-95