The park was huge, bigger than Dean knew that expecting to find the wolf was highly unreasonable. He knew that he was taking a chance, hunting the thing on his own in a place he didn't really know. But, then, he'd hunted for worse in more unknown territory. He just didn't like the idea that if he got it wrong, he'd be killing some poor slob.
The older Winchester pushed all doubts aside. Black wolf. There hadn't been many of those reported. He might have gotten a little information from Jennifer, but he tried to make sure his inquiries were couched in the research mode. He didn't want to tip her off to what he was doing. Sure, he was going to hunt the thing; he just wasn't clear on the when or the how. Black wolves had been low in number, especially ones that looked like the thing from the zoo.
He moved quickly to the heavily wooded area of the park, guessing that was where the wolf would be rather than out in the open. Having Sam along might have been helpful, but Dean just couldn't take the chance with his little brother, especially when the kid tended to have very dog like tendencies.