Nostrils "whodathunkit" Great entry, unfortunately you have overexposure on the white sun lit aspect of his snout and this speaks of exposure calibration mal function. Are you shooting on A mode or Manual. Switch to manual, bit the bullet and you will see you have a lot more creative power to image making. I love your artistic crop with keeping part of the horse's body in place but softened. It is a photograph that is warm in beauty....and it's of nostrils....breath....life.

A blow out is when all photographic information is completely lost and no matter how much you burn and burn and burn and burn in your "darkroom" that information is gone and you only have a white blob. A black out is the opposite and also called "clipping". You may want sun to shine but you don't want white blow outs....do you? Also remember that the natural pathway of the eye is to always gravitate to the brightest part of the canvas and that is what and where the focus will be. In the olden days, photographers used to turn their photos upside down, and look to see where their attention went...when it went to the brightest part of the image that is where the attention (focus) was....and then they knew that it wasn't on the focal point intended.

It's because I was born in 1924

Yes, I agree with showing detail of feathers. The curvaceous lines they create add to the beauty of the detail of each feather. There are some very strong blow outs at the top of this image. This was not an easy photograph to take with such strong sunlight and a black swan, you do know how to challenge yourself. I hope you are shooting on M mode and that gives you greater creative leeway than just automatic. I like how you have practically filled the entire frame with feathers.