"Ravens and jays heard calling after the owl was abroad: in conversation with the restless dead..."
That's the kind of thing Hild, the main character of the novel I've just finished, tells those she wants to frighten into listening to her advice. It works, mostly. Given her situation--young woman in a dangerous age--she finds it expedient to play the role of seer and prophet. She isn't--there are no fantastic elements in Hild, no magic but that of the natural world--but she becomes an observer of people and nature. She learns to predict behaviour--of people and systems (the weather, for example). She builds herself a reputation. (No, not like Miss Marple. Unless it's the alternate universe in which MM kills people, has wild sex, and plots more intricately than bishops and kings. That would make a cool TV series...)
Birds are a favourite indicator. One of my favourite research texts was a PDF a kind reader sent me a couple of years ago of a century-old book The Birds of Yorkshire: A historical account of the avifauna of the county, by T.H. Nelson. It's a wonderful book, full of just the kind of nifty oddities (albino magpies, nest-sharing doves and starlings, oddly-coloured eggs) a seer might need.
It's been interesting writing about a world utterly ignorant of science. (A useful book was Elves in Anglo-Saxon England, by Alaric Hall. I discussed the text and the thoughts it triggered--about elves and gender and fantasy--at length here.)
Hild is a naturally suspicious child, not inclined towards belief of any sort. But she does occasionally make up reasonable-sounding stories that fit the facts as she knows them: Swallows hibernate in a vast underground cavern all winter and emerge only when it's warm. Rainwater is some god's tears. The north wind comes from the great black cave of Arawn. (She lives in a world of Germanic and Celtic and, later, Christian belief.) And of course she can't know anything about death.
Hild's contemporaries find Hild uncanny--she's unnaturally tall, unnaturally clever--and suspect her of being, variously, part hægtes (witch) or part etin (giant), and occasionally possessed by an ælf (wicked and terrible, nothing like the diminished creatures of Santa's workshop) or wight (ghost). She is not above using these rumours to her advantage, although this choice comes back to haunt her. It's a dangerous thing to be other in a marginal culture.
But that's a whole other blog post. Happy Halloween.