Bucking explained
Bucking is traditionally considered a form of “naughty” behaviour in horses. Wikipedia defines it as follows: “Bucking is a movement performed by a horse or bull in which the animal lowers its head and raises its hindquarters into the air, usually while kicking out with the hind legs. If powerful, it may unseat the rider enough to fall off.” However, the most important thing to remember is that your horse can only communicate his pain, discomfort or confusion through his behaviour. So, don’t simply dismiss your horse’s bucking as naughtiness, but check that there isn’t an underlying problem causing this reaction.
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Let’s take a look at the top five reasons why a horse may buck.
1) Release - Horses in fields will buck of their own accord, often attributed to “high spirits”, these horses generally appear to be revelling in the sensation and freedom of movement.
2) Fear – Horses will often buck when startled or scared. This is part of the flight response that keeps them safe from predators.
3) Pain – Horses cannot tell us they are in pain, often there only form of communication is through “naughty” behaviour. “Understanding Horse Performance Brain, Pain, or Training?”  by Sue Palmer, (https://www.ethicalhorseproducts.co.uk/Books/BPT/) helps you to realise when your horse’s behaviour is trying to tell you something.
4) Confusion – Your horse may not understand what you are trying to ask of him, he may react to this confusion by bucking, as he will want the confusion to stop.
5) Learnt behaviour – A horse (or more often a pony!) may have bucked once, often out of confusion, and then the rider may have dismounted. If this pattern is repeated a few times the horse may learn that if he bucked, he is essentially “rewarded” by the rider dismounting. It is all too easy to get into this scenario with your horse. If you are struggling consider consulting an equine behaviourist IHRA (Intelligent Horsemanship Recommended Associate) to help.
It can be really frustrating trying to figure out why your horse is bucking, but if you take your time and patiently work through the options, you will find the root of the problem. Remember horses can only communicate through their behaviour, there are very few naughty horses, but there are however lots of horses in pain, scared or confused. It is our job as horse owners to understand their behaviour and work out what they are trying to tell us. 
Lizzie Hopkinson is a partner at www.ethicalhorseproducts.co.uk
photo (copyright Simon Palmer)