He was born on June 26, 1921 in what is now Martin, Slovakia.

He died at age 50 of leukemia, in Prague.

https://fishinkblog.com/2014/12/12/mirko-hanak-a-world-of-nature-in-watercolour/
(animal paintings; this includes the cover of Bambi)

https://one1more2time3.wordpress.com/2010/12/12/mirko-hanak-1/
(more - this includes a comment from Gene Deitch)

From the blogger:

"...his amazing watercolors are a cross between chinese traditional watercolors, the minimalist japanese painting-style and the czech rich culture in illustration. hanak was famous for his distinctive illustrations with natural themes, portraying life of plants and animals with broad watercolor strokes mixed with beautifully balanced finer brushwork on rice paper, all that in stunning compositions and colors full of life."

https://www.tumblr.com/tagged/mirko+han%C3%A1k?sort=top
(more animal paintings)

https://www.pinterest.com/zarasai/mirko-hanak/
(some artwork)

https://genedeitchcredits.wordpress.com/roll-the-credits/60-mirko-hanak-charlottes-web/
(some B&W drawings he did for the 1970s movie of Charlotte's Web - but they were never used)

https://www.awn.com/genedeitch/chapter-thirty-charlottes-web-graphics
(same, plus a couple of colored illustrations)

https://www.amazon.com/s?k=Mirko+Hanak&i=stripbooks&_encoding=UTF8&camp=1789&creative=390957&linkCode=ur2&linkId=GTRBIJEXTP3R3PDJ&qid=1431326728&tag=owlbarn-20&ref=as_li_ss_tl
(some book covers)

https://geonmagazine.com/culture-places/culture/mirko-hanak-and-his-amazing-watercolors
(from two days ago - brief bio and photo)

Quote from Hanák:

"There are many people who love nature and don't run around the woods with a flintlock, but I stubbornly cling to the observation that there are times and places where only hunters meet. I know for a fact that if it weren't for the rifle, all my work would surely have taken different paths. We have had things together that I find beautiful and important that I must tell of.."

https://www.youtube.com/watch?v=EI56LWbNM4c
(short slideshow - it includes drawings for Snow White, Puss-in-Boots, and Beauty and the Beast)

https://www.youtube.com/watch?v=9eX9IR6TpVM
(another slideshow - 7:21 minutes)

https://www.goodreads.com/book/show/22371422-the-kingfishers
(reviews of The Kingfishers)

I own that book, plus Ryn, the Wild Horse, by Bohumil Riha. Review of that one (no comments on the illustrations):

https://www.kirkusreviews.com/book-reviews/a/bohumil-riha/ryn-the-wild-horse/

Forgot to say: I can't imagine why he was never a finalist for the Hans Christian Andersen Award. Personally, I don't think the work of Jiří Trnka (who WON the award) can hold a candle to Hanák's, but what do I know?