I think you missed my point, and perhaps I worded things badly - "proof" was clearly the wrong word, "evidence" would have sufficed. Allow me to reword:
The only things we have to go on are the word of mouth anecdote in the article and the likelyhood of such an event taking place. As for the anecdotal evidence, one has to wonder if the chance of the RSPB/The Volunteer lying outright to get press coverage, as some have suggested they did, isn't going to be a wee bit lower than the chance of such an event taking place anyway - as we've agreed, uncontrolled dog incidents are hardly rare. I was merely suggesting that accusations of lying were, perhaps, slightly premature, given even less evidence to support them than there is in the original story.