I realise I am picking one sentence out of context, but I think an important factor is population turnover. I believe that Buzzards (and probably Red Kites) will out-breed low level persecution - which is probably the best term for what we are suffering in Ireland. The eagles, taking so many years to mature and producing maybe a single chick in a good year are very vulnerable to the drip-drip effect of a minority of farmers/game rearers/whoever picking off birds.
Absolutely, agree entirely, but, even though Buzzards and Red Kites are likely to produce enough fledged young to compensate for low-level poisoning, it is surely, at least on a local level, still a significant limiting factor. Until such time as the Red Kites begin to breed (fingers crossed for this year, I would assume that the pairs that failed last year will be that bit wiser, and some new pairs may also at least attempt to breed), they are still very vulnerable to poisoning, of course (though, in the long run, second-generation rodenticides could cause far more problems for this species in particular). As you say, the eagles, especially Golden, would always have low productivity, even under ideal conditions, and will always be vulnerable to even low levels of poisoning.
Buzzards have been poisoned and shot in this area too, but not in any sustained or targeted way as far as I can see, just people who shouldn't be allowed to own pointed sticks being permitted to hold gun licences.
Any time I meet people and mention Buzzards, I point out that they eat such popular creatures as rats, rabbits and young crows taken from the nest...they're practically the farmers' friend! If even a handful of people gain a greater appreciation of the benign nature of these mysterious birds that are becoming more and more familiar down here, then that would be great.
Regards,
Harry