Thanks guys, this image still looks dark on my dad's monitor, so I'm going to go with the flow and say it's still not right. I'm waiting on a Huey pro to be delivered, hopefully that'll sort out the monitor issues. These guys are always around their nest, and it's easy to get to, so plenty of photo opportunities. They have such wonderful eyes, and so far seem very unnaggressive.
The histogram didn't look too bad, no blown highlights or dark sections, but was slightly orientated to the left with the peak, so I guess it the image is underexposed by about 1/2 stop or so.
I've changed several things in my Photoshop workflow, I have a new way of adjusting colour balance with the shot, contrast and also hue/saturation of the image, all of which I think are better in the long run. The interesting thing is that I've noticed the Neat Image profile being much better than it ever used to be. Quite frequently, I'd only get 75% match for the profile, but now it's usually in the high 80s or 90s, which means I must be doing something better with the images 
Greg - yes, that's an egg you see!
Dave