The topic of talon-grappling, cartwheeling etc. is covered in the Poyser monograph The Golden Eagle. Such behaviour is more common (apparently) in Sea/Fish eagles however it quotes a study showing that 80% of 107 well documented instances amongst these species were aggressive largely refuting the view that it's a courtship behaviour.
It probably occurs more often in golden eagles than is written up . I spend a fair bit of time watching/monitoring eagles and all the talon-grappling I've seen (including several instances this year) both between golden eagles and golden & white-tail has been aggressive or appeared so. I've seen white-tails do it in circumstances suggesting it was possibly courtship but it could have been an intruder or like the situation in the ref Farnboro John quoted of 2 males vying for a female.
cheers, Andrew
I've seen White-bellied Sea Eagles and Lesser-spotted Eagles engaging in talon-grappling and in both cases it was clearly not a display act, both sets of birds narrowly avoiding death by separating just feet before crashing in to the ground / Ocean. I think you have to be pretty lucky to observe this behaviour unless youare able to watch birds over very extended periods of time.
I'm chipping in very late here and I'd lean toward the generous side and say that it is 'possible' that an Eagle was mobbed by a Buzzard? I'd like to know the % of claims at this site which are proven to have been Eagles, they are probably, hugely over reported by inexperienced birders who go there expecting to see one.
Those with little experience of 'Goldies' are really unprepared for the size difference between them and Buzzards and I've even heard people say 'Eagles were everywhere, sitting on fenceposts at the roadside!' after a week in Scotland when what they saw were clearly Buzzards which are big, but not that big!
What has been described is not impossible but highly improbable and the photos don't really help to resolve it.
Andy