Natural History authors tend to prefer an essay or journal form that lends itself to description and reflection. The writing tends to be deliciously straightforward and contagiously enthusiastic. Something the writer has observed or experienced in nature has sparked something within them, and their goal is to communicate that spark as purely as possible. If they are successful, then the writer and the reader can together make something meaningful out of a chickadee, or a sand dune, or an elm. We are drawn in to wonder, to learn, to celebrate.
Most creative writing depends heavily on the exotic for its appeal. Everyone loves crime, lust, strange customs and faraway places. Natural History writers spurn this approach and deliberately choose what is present and local. It takes immense skill to write strong enough to create interest in what most people accept as familiar, and it is for this reason that I believe Natural History stands in the gap between fiction and non-fiction. The best nature writers completely disappear, leaving you sitting motionless on a dark bridge watching for muskrats, or scratching for shellfish on the eastern seaboard at low tide. This is a remarkable feat, for it means expanding a mere account (I went there and then I saw this and then I thought that and then I felt such-and-such) into an experience for the reader through sheer force of prose.
Photographer's work at developing their eye, and nature writer's work at developing all of their senses - so they can describe with nuance and conviction. There are no fixed rules for how to write knock-down drag-out descriptions, but as Susan Sontag says, it always begins with paying attention to the world.
Anyone aspiring to write would do well to make a pilgrimage to Tinker Creek, listening to the birds, getting some blisters, and honing the power to describe.