If you have to ask, you don't need the DSLR.
DSLRs are big, heavy, and bulky. They take lovely pictures, but you need to spend time getting everything set "just so" which eats into your riding time. If you're a professional photographer and plan to ride a bike between taking pictures, you wouldn't have to ask.
Other people take pictures to document their ride, and these people (most of us) can find a smaller camera that will do it just fine. We'll be a bit frustrated that the light wasn't just right, or the air was a bit hazy, but we don't spend a week at one place to run out at sunrise and sunset to get those perfect pictures; we're riding bikes to someplace else the next day.
I would be surprised to see a casual (non-pro) photographer get a good picture of a flying bird. They're even more elusive than the perfect sunrise shots, since the bird isn't always the same place the next day like that mountain range is. You can get a super zoom compact, but it's no good at extreme zoom unless you've dug out the tripod, found a place to set it up, mounted the camera, and ... hey! Where did the eagle go?
BTW, you can buy professional quality pictures of most scenic spots for a quarter or so. They're called "postcards."