One of the first questions that needs to be answered here is what level of disturbance to birds (be it from tapes, flash, baiting etc) is acceptable? Most will probably answer as little as possible, but as a starting point we have to accept that both birding and bird photography do inevitably cause disturbance to birds. And, since a photographer almost always needs to get closer than a birder, photographers usually cause more disturbance. In some countries with a mature birding scene, photographers as a group end up being despised by birders for this reason alone. Whilst I appreciate that this isn't the case in Hong Kong, I'm not sure that drawing up a guideline for photographers, based on the weight of votes from birders, who have different requirements and sensitivites, is the way to go.
That said, what is "disturbance", and when does it matter? To me, disturbance is evident when a bird stops what it would otherwise be doing, i.e. feeding, to look at a birder/photographer. The bird may resume what it was doing, either immediately or after moving a short distance away, or may flush and fly some distance before resuming it's previous behaviour. At this level I don't think the disturbance matters, and indeed the birder/photographer concerned may not even have been aware of the birds presence. What does matter, is when the action of causing the bird to modify it's behaviour becomes deliberate and occurs repeatedly. Disturbance has now become harrassment, and it's for this situation that I believe a code of conduct is needed, with suitable sanctions (of which more later).
However, I think that disturbance/harrassment is not a black and white subject. For example, should species which are abundent in Hong Kong receive the same degree of protection as rarites which are globally endangered? Is tape luring and food baiting a Tree Sparrow (!), and then photoraphing it using flash at full power, as equally awful as causing any disturbance whatsoever to a visiting Crane sp.? Is photographing a Chinese Bulbul at the nest, using flash, as criminal as photographing a breeding Brown Fish Owl with flash? Common sense needs to prevail (and more of that later too).
Additionally, does it matter where the disturbance occurs? Do the same rules of conduct apply at Mai Po as elsewhere in Hong Kong? To me, being on a reserve means that different, more restrictive rules probably apply, and this is sometimes the case in overseas reserves, where there might be a complete ban on the use of tapes for example.
With regard to releasing news of rarities, I think that this has to be a judgement call on the part of the finder. A rare bird in the process of nesting can obviously accept little or no disturbance. The record needs to be documented, and an inexperienced observer might feel the need, for example, to call in a member of the Records Committe to confirm the identification, or might want to call in a single, trusted photographer, but otherwise keep quiet about the site. At the other extreme, the recent White-bellied Green Pigeon was a Hong Kong rarity, but so tolerant of the presence of observers that the crime here would have been in not releasing the site info. Again, common sense has to prevail.
So my feeling here is that it's very difficult to come up with a rigid set of guidelines. Certainly, they should be no more restrictive than those in force in other countries where birding and bird photography are commonly practiced. I don't think any country makes an outright ban on the use of tapes, or food baiting, or the use of flash, although individual reserves may have more restrictive rules.
That said I do think that we need a set of guidelines to convey the sense of what we as a group feel is generally acceptable, and with sanctions for those very, very few who insist on blatently and repeatedly harrassing birds. I think that most of us instinctively know when we've crossed the boundry into the unnacceptable. That little prick of conscience, the unspoken question "should I really be doing this?", or "would I want anyone to see me doing this?". I dare say most of us have been there. For those who reach this point and back off the sanctions should never apply. For those who repeatedly press on regardless, they would. Sadly, simply being a good, or well known, or experienced photographer doesn't necessarily qualify you in bird photography ethics.
So, what meaningful sanctions do we have at our disposal? Well, how about the cancellation of the offenders Mai Po permit? Know any serious photographers who could live without a Mai Po permit? Is it possible to obtain a Mai Po permit if your HKBWS and/or WWF(HK) membership application has been refused/cancelled? Yes, pretty serious stuff, but my hope would be that this would never, ever have to be invoked, and that the mere threat of the existence of such a sanction would be enough. Also let me repeat the phrase COMMON SENSE SHOULD APPLY. The idea of such a code is not that all photogaphers, or birders for that matter, should live in constant fear of being reported for the most minor of infractions, or that political correctness should run riot, but that repeated, blatant harrassment of birds should be punished.
My two cents worth.