Ecological speculations: Nykoraptors are likely to be opportunistic predators, and probably scavenge the kills of larger dinosaurs as well. They probably rely on their speed and climbing ability to survive when a bigger predator comes after them. They may sometimes hunt in pairs or groups as suggested by the pair in "Nightfall", but also probably hunt alone given the solitary one seen in "The Runaway".
Given the sickle claws on each foot, Nykoraptor is presumed to be either a dromaeosaurid or a troodontid (the two subgroups of the Deinonychosauria). More likely it is a dromaeosaur, since the name "raptor" is usually associated with this group, and the shape of the head also appears more like a typical dromaeosaur than a troodontid.
Nykoraptors have some resemblance to Neuquenraptor (illustration here), one of the few dromaeosaurs from South America (where Carnotaurus fossils are from). Some other dromaeosaurs from South America and Africa (which broke apart in the Early Cretaceous) are discussed here. So one might imagine that Nykoraptor is fairly closely related to some of these, although if there was a land bridge between North and South America as discussed in the Science & Speculation section of the Ankylosaurus article, one could also imagine it was more closely related to North American dromaeosaurs.
It is shown to be capable of climbing trees. If this is common behaviour for the species, then it may sometimes store the carcasses of its victims in the branches and come back for them later, similar to leopards today.