Late September into October is the moose's annual mating season: the rut.
Bull moose will be almost constantly on the move; traveling from cow moose to cow; to smell whether she is ready to breed. Here is a series of images that showcases this behavior.
When love is in the air and you're out making images, be on your guard. The bull moose's behavior regularly seems to upset the cow(s) and they are known to make a run for it. You better not be too close to the cow or be looking through the view finder when she goes!
As I've seen this happen regularly - one occasion even involved a photographer having to jump out of the way - I'm always studying the cow moose for signs that she's had enough of the bull.
My favorite focal length range for the moose rut is around 100 to 400mm. Any shorter and you'll find yourself too close to the moose; any longer and likely you'll find lots of vegetation in the way as you'll have to get too far away to fit the (large) moose in your frame. I like to make both close-ups and shots that include scenery so I typically use my Nikon 70-200mm f/2.8 lens and Nikon 200-500 f/5.6 lens.
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