There are certainly some species for whom the term "family group" does not apply.
Bryan Nelson, writing about the gannet fledgeling, says "Its parents do NOT accompany it and so it is thrown entirely on its own resources. If any adult DOES feed it at sea, this can be only an exceptional piece of luck. [it is so fat that] is has fuel for perhaps 1-2 weeks . . . . . " When the young gannet has lost enough fat and is strong enough to fly, it may latch on to any passing adults and fly with south them. Thus making what looks like a family group, but really isn't.
So, often ringing data is required to build up the picture of which species do, and which don't, travel in family groups.
With regard to great spotted woodpeckers, I observed a similar situation to Mark when in Scotland a couple of years ago. After several days, two adult males were seen together, confirming that there were two family groups involved - with a total of five youngsters - at the feeding stations. The family with three youngsters appeared to be dominant at one of the feeding stations. At the other, further from the trees, it seemed to be a case of whoever was there first was dominant.
Annie
