[Edit 3] Nocturnes live to be about 80 years only max. They reach sexual maturity in the early teens, and reach full adult size (7-8 feet tall) at about 20 years. Health starts to decline when they reach about 45-50 years.

[edit2] they can live anywhere, but just like most animals, not in areas greatly populated by humans. Human interactions occasionally occur though depending on the region.
It varies with each individual but most hunt during the day/evening
as fare as social behavior, once again, it depends on the individual, Nocturnes tend to be somewhat solitary, but will group together in feeding and nesting spots (just like parrots) or if they have a family established
Nocturnes generally only fight over mates (both males and females) but some tussles break out over food. Each has a territory, but most territories overlap.

Nocturnes have very few predators due to their size, strength and speed (and their own position in the food chain)and don't rely too much on camouflage.

though they lack eyes, Nocturnes can see color and light due to photo-receptors located in the skin covering their echo locating organ (which fills in blotches of color and light with shape)

[EDIT] Now with standard horn and tail design. Also, a reminder that Nocturnes are primarily gliders and runners, but are capable of self-propelled liftoff and brief periods of actual flight with the aid of much flapping of wings (used to escape enemies and searching for prey). Mostly they use their wings for aiding in scaling trees/cliffs, and navigating trough/around said objects (such as navigating branches without having to jump to each branch at a time etc) as well as displaying for mates and warding off predators and rivals [END EDIT]

New ref for Greater Nocturnes (also doubles as Nacht's new ref). Changed their design a bit and got rid of some stuff that was bugging me (the ankle plates being one of them). I was inspired by Animal Planet's "Dragons: a fantasy made real" to make them more avian-like, but I kept the arms/hands the way I did because they still serve the purpose of dexterity for manipulating objects (still deciding if I want to keep them like that)

All other information is the same with the exception of whatever pertains to old anatomical features (their sound receptors no longer bulge out awkwardly but are now very slight indents where the organ is located in their skull) and horns and tail variants.
They now have a set horn and tail design with very few variations (if any) that is omitted from this picture because I haven't decided on the exact appearance.
Also, their brighter markings no longer glow (though I am still debating this)

Greater Nocturnes and art (c) =DemonML