With the first image, your shutter speed is way too slow, but you have actually got away with it this time. Your problem is virtually impossible light angles; which have over exposed the bird's head.
When faced with this sort of scene I immediately make an exposure compensation adjustment; but so often, just like with insects, getting an exposure to suit the brightest areas means the midtones and shadows get overly dark. However, you can usually recover something from the shadows but over exposed highlights are lost forever.
It would be possible to selectively darked the bird's head area but you still won't recover those fine details.