Fenix is generally a good option, especially since you're familiar with one of their older models. In addition to Zebralight, there's also Nitecore, Armytek, Olight, and Thrunite. I'll cut the list off there rather than overwhelm you with choices among the lesser known brands.
Two features that are important to me personally, and why I tend not to be very interested in most Black Diamond or Petzl models are:
1.) Regulated output - this keeps the brightness stable as battery voltage declines. Unregulated lights can achieve very long run times, but at gradually declining brightness.
2.) Neutral white color temperature - after dark, I tend not to like the blue-hued "cool" tint of a lot of LED's. I think others are moving away from this lately, but they don't always advertise it clearly.
I also really like high CRI (Color rendering index) lights. Because high CRI lights more evenly reproduce the full spectrum, objects illuminated by them appear more naturally colored. I think that's a great feature to have for studying wildlife.
With that in mind, if I were going to make a singular recommendation, it would be a Zebralight H600Fc Mk III, which is a neutral white, high CRI model powered by an 18650. It has a "floody" beam profile that gradually fades into the spill with no distinct hotspot, so it fills the full central portion of your vision and some of your peripheral vision. There is also a normal hotspot + spill version available (H600w Mk III) that is better for seeing further down the trail, but is not available in a high CRI version.
However, I do suggest giving the details about the user interface on their product page a read to be sure at least the basic operation makes sense to you.
And if Zebralights don't appeal to you, there's plenty to like about other brands, too. Just add more details about what you're looking for.