Snowy Egret

I think you did a good job with the exposure on the whites and as you say the overcast probably made it a little easier.  The large image helps a lot with the separation between the dark background in the dark beak.  I think you could probably crop it a little closer to the head.  A nice image overall.

I second David's comment. It would be a stronger image if you were at a lower angle but that may not have been possible. 

Very nice detail in the whites, Shirley, and as you noted the cloudy sky helped in that.  I like the pose and the visibility of those great yellow feet.  It's probably just taste, but I think I'd crop this to a 4x5 vertical as there seems a bit more space both top and bottom than necessary.

As a side note, I don't know what kind of software you're using, but I've been using Topaz Detail for bringing out texture in feathers.  In the menu you can select just Highlights and I created a custom formulation there that I use as my starting point on white birds.  I was using the shadows/highlights tool which someone showed be, but it was very easy to overdo it and make things look weird.

Nice detail in the egret Shirley, and I love the contrast between the bird and dark background while still seeing the log perch. I think you've received some valid comments which would improve the image, and I think Dennis' suggestion with the crop would help by lowering the perspective-bringing the bird closer to eye level.

Nice job with exposure, Shirley.  To me there's too much space up top.  Cropping down about half way toward the head would work nicely.