So noisy or not doesn't matter?
The conditions do not make reference one way or another to noise so from an NRCoC perspective I do not think it matters.
However I would point out the
Railway Byelaws and specifically Byelaw 6(8) contain the following provision:
No person shall molest or wilfully interfere with the comfort or convenience of any person on the railway.
Bringing a duck onto a train when you know the duck is going to be noisy could potentially be considered contravening the above Byelaw.
Question:- Has a duck ever been in a passenger compartment before?
Over the long history of railways in this country I'm sure that most if not all species of animal native to this land (and some that aren't) will have been conveyed or been in a train at some point.
The pet carrier rule seems slightly odd, as a friend of mine has a large Maine-coon cat that goes for walks with a lead and harness and behaves perfectly fine. I can't imagine he (the cat) would cause any trouble on a train journey but getting him into a cat carrier is quite a mission in itself!
I imagine it's a case of needing to draft rules to cover the majority situation rather than trying to fit every unique situation. The vast majority of cats are not trained to be 'walked' like a dog would be so rather than leaving it up to the judgement of the individual owner it makes sense, to me at least, to just have a blanket rule. Admitted in some cases it may not be necessary but it should save aggravation on all sides by having plain and simple rules to deal with animals on trains.
Come on you must have had at least one interesting animal on a train of yours before now!