I jump at the chance to take pictures with contrasting exposure values. Bald Eagles are a perfect example. I mean, to a camera, that sucker may as well have a Disco ball for a head. Meter for the feathers, and the head is over exposed. Meter for the head, and everything else goes dark. there’s no perfect solution, no fast rule about averaging exposure. The best solution I’ve found is to change my perspective and try to get a different light angle on my subject. Sometimes, I just wind up getting nothing and have to wait for another day.
The top two pictures were taken in the afternoon of a bright, cloudless day. The light was very bright. I used my spot meter, first on his shoulder, then on his head. I got the third shot with my center weight meter from another side of the enclosure. Still, a good day to take pictures of the gators. the last picture was taken on a cloudy day. The indirect light made metering the eagle much easier. I just used a center weighted meter, covering most of the bird.