Is this defensive colouration?

Is this defensive colouration?

Observation - Is this defensive colouration? - UK and Ireland. Description: I suspect there are several pictures of these very obliging London visitors on iSpot. Added these ones here on the basis of a discussion I had with other birders at the 'twitch' about the appearance of the birds from the rear.

I suspect there are several pictures of these very obliging London visitors on iSpot. Added these ones here on the basis of a discussion I had with other birders at the 'twitch' about the appearance of the birds from the rear. The impression given is (to my mind quite strongly) is that of the a head of a much larger bird (the wings forming 'eyes' and the tail the bill).

I speculated that this could be defensive, giving the impression of a much larger bird (about goose sized) which might deter a predator like a Sparrowhawk from trying to take them.

The brief research I have done so far does not suggest that this is the case (it's not mentioned). Does anyone know?