Welfare before the picture
Disturbance is not always obvious. A bird that flushes from its feeding spot burns energy it may need to survive a cold night. A deer that stops grazing to watch you is losing feeding time. A seal that shuffles into the water from a haul-out is spending effort it would rather save. Learn the signs of stress: repeated alarm calls, head-up staring, freezing, tail flicking, or moving steadily away.
When you see them, back off quietly and give the animal more space. The Audubon Society's Guide to Ethical Bird Photography puts it plainly: the well-being of the bird and its environment comes first. That principle applies to every species.