Ducking the Issue

I'm in trouble again and it's not my fault.

I was in the garden at the weekend, snuffling about in the back border, next to the house (there's a reason why we're called border terriers) when I discovered a duck.  It was a bit of a surprise to be frank.  It's not even like we're near any water.  She left it a bit late to shift as well, so there was an exciting moment when I chased her down the garden before she cheated and took off, leaving me barking in her wake.  I got told off by 'Him Indoors'.  Anyway, I returned to the back border to see if there were any more ducks lurking, and discovered a nest full of eggs.  When 'Him Indoors' found I'd chased her off her nest he was even more cross with me.  'Her Indoors' did point out, rather lamely in my opinion, that it wasn't my fault, but 'Him Indoors' was rather put out about the whole thing, particularly when the duck didn't return to her nest.  I found the term 'duck murderer' a little bit strong, particularly as the eggs hadn't even hatched.  At what point does an egg become a duck?  'Junior Him' pointed out that it couldn't be murder as I didn't have 'guilty intent' - that A-level in Law was bound to come in handy at some point - so 'Her Indoors' suggested an alternative plea of manslaughter on the grounds of diminished responsibility due to a terrier disposition.

The following morning, just as the whole episode was slipping quietly into my back catalogue of misdemeanours, I made the mistake of double checking the back border just in case, and found she'd returned over night.  It was like being stuck in a repeat episode.  On this occasion however, the duck returned a short time later and after much hesitation, returned to her nest.  I'm now only allowed in the back garden on my lead and under close supervision.  Does anyone know how long it takes for Mallard eggs to hatch?