Does it look like character displacement?
By the fact that these two species feed at different moment of the day, they therefore have slightly different ecological niches. It is indeed the type of consequences brought about by character displacement. Yes, it looks like character displacement.
"Resource partitioning" is not necessarily more behavioural than anatomical and even if it was, a behaviour is a phenotype, just like any other phenotype, and it should not be disregarded. The character being displaced in a 'character displacement' scenario can be behavioural. So, yes if two species evolve to prey at different time of the day to avoid competition, then they have evolved so as to reduce the overlap between their ecological niche and we can call that character displacement.
Is it character displacement (highlight on a few missing information)?
It is possible (likely) that they evolved to feed at different times as a reaction of their competition and hence it would be called "character displacement" but technically speaking the question does not explain how these two species had been diverging in their feeding. It is possible that divergence in their feeding time happened long before being found in sympatry. In fact, the question does not even make clear that the two species are found in sympatry.