Word of the day: crepuscular
It means an animal that is active in twilight (as opposed to nocturnal or diurnal). I ran across it in an article about weasels (which are mostly crepuscular, unless they get the wicked munchies). Crepuscular can be further divided into matinal and vespertine — active at dawn or dusk. Derived, I assume, from the morning and evening prayers matins and vespers.
Animals can change their time orientation in response to local threats (such as the presence or absence of certain predators). I assume living on the edges of human civilization tends to push animals toward being nocturnal or crepuscular. At least, in my own experience hiking suburban conservation lands, I am far more likely to see animals when I go out very early or stay out late.