'Groucho', the young sparrow sitting on the patio table a few feet away, doesn't seem to join in the mêlée. He (I'll call it a he) sits fluffed up, looking even younger than he is, like a fluffy chick. Perhaps he's under the weather. He gazes intently at the patio windows, hops over to the back of one of the garden chairs where he does a series of little press-ups (up and down on his legs, that is) then flies down and sits on the rim of the patio windows, looking in as if he would like to join us for breakfast. Barbara has even seen him trying to fly in through the glass.
Perhaps the reason for the variation in sparrows, the reason they're recognisable as individuals, lies in their sociability. They need to know who's who in the pecking order. All part of their rich social life.
Part of their success must come from their individual, sometimes seemingly eccentric behaviour. Sometime these strange behaviours are going to pay off.