At the beginning of learning to draw it is ok to copy photos 1:1. It is the same our ancestors did years ago. Like Albrecht Dürer. He had to copy the arts of his master before he was allowed to do his own work. They learned: how did Master draw this?
If you copy photos, you shouldn’t only draw, better you ask yourself questions while drawing.
Real birds are difficult to draw. They’re too bustling. It is difficult to see exactly each feather. (I’m thinking of a small bird, like a great tit.)
I’ve seen many zoological specimens that doesn’t look like the real one. It is often the expression or the gesture that doesn’t fit. So you can also learn wrong things of the specimens. Another point: the color of the specimens become pale and the glance of the feathers is gone. (The good specimens are closed away, because they’re too valuable to show them to everyone.)
And dried specimens are also artworks! A work of an artist!
In my opinion you should have seen the species you want to draw in real before, to know how they act and behave.
I think, copy photos 1:1 is ok at the beginning of learning. You also can use/copy photos to create your own work. Like you do this with specimens.