I don't know if it's just me but I noticed animals tend to have strange behaviors when in front of the lens:
Like ostriches who seem to only care about taking a bite out of the camera (and shirt, and hair, and cap...)
If it's a giraffe, they're quite efficient at cleaning your lens...
All others turn their back on you as soon as they see you coming, having absolutely no interest in being pretty in pictures. To put it bluntly, rhino butt cracks don't make art. And when they do, it's usually smelly bronze sculptures.
For me, zoos have become a big no-no.