One thing about a lot of wildlife, its come and gone before you know it. A split second of something, is often all you'll ever get. If you're not fast, you wont have pictures. Think about it, I waited a few hours for this 100th of a second.
The other thing is get level. What I like most abt this image apart from the motion is that you can see the space between the ground and the belly. It's an animal that spends its life close to the ground, in the undergrowth. Its a long animal, its a hairy animal and a quick one. The image manages to convey all of that in an abstraction.
A head would distract from this message, it would give the animal an idividual personality, perhaps an expression. And we would be diverted there...maybe not such a bad thing, but it wouldnt be this picture...
This picture for example, it suggests, tall, or actually long since the animals arent usually standing. but it adds other elements, vigiliance, and for me certainly humor in that bow-legged very awkward looking hind leg stand. theres the other elements for instance, where did this neatly peeled banana come from? and mongooses eat bananas?
This other image of the mongoose standing taken from the back, on the other hand ,has tall / long and vigiliant. none of the other elements. its not funny, either which could be good or bad....
The subtext to all this is that photography often is about deciding how much to leave in or out. not only in elements but even in subjective experience of a picture.
Some pictures base themselves on a narrative in the elements that are in the picture. the one below for instance, theres a temple, theres offerings, theres a mongoose eating them, theres a larger looking mongoose (most likely mum) hanging around waiting in the background. you can construct a fairly complete and complex narrative around that. And these are apparently all the rage now, the complete story in a frame.
but there are complete, if not complex stories, in shots like the first one. removing elements from an image does not necessarily compact the scope of an image. but it does place greater demands on a viewer. It is therefore harder to pull off successfully.
Usually its got to trigger some instantaneous gut feeling. then give you just a couple of details and leave you with that.
the first picture, hey whats that moving so quickly. hmm legs, fur = animal, probably some long thing, didnt fit in the picture. wheres it going to in such a hurry? maybe its escaping from something. maybe not, thats always how you see critters, scurrying off to their next unknowable task...furtive, hiding under stuff, bellys scraping the ground. no wonder we hardly ever see em. just some blur off the corner of the eye. .....no wonder the weasel (this looks like one) has been associated with sneakiness...and so on
if that tenuous something can be triggered i think a photo works. off course i dont know if it does for you, you could tell me. but thats (sometimes) what i try and guess at when i pick something and discard some pics...