Many newts and salamanders secrete toxic substances from glands in their skin to deter predators. Some are merely irritating or distasteful, while others can kill an adult human. I noticed patches of blue-grey on the head of this newt and on the knobs along it's spine, and it was staring at me and rearing up on it's hind legs in what might have been a threat display when I first noticed it. This species is supposed to be quite docile, but a few days ago, I introduced a new female that was possibly gravid (carrying eggs), so the males might be getting a bit hormonal now.