I can stare longer than you! A "resident" of Grizzly Ridge - St. Louis Zoo interacting with several young visitors. The next frame taken in a sequence has the young visitors smiling / laughing and the bear appears to be doing the same!

This was taken looking through a viewing window 30+ feet away.

Nikon D800 w/Nikkor 24-85mm f/2.8-4D

@85mm, f/4.5, 1/160s, ISO 1000

cropped