Why does my horse try to eat birds?

Seriously? Horses eating birds?
Why do horses eat birds? might not seem like the most obvious title for an equine health blog but we like to cover all bases. And this is indeed another base that needs covering. In order to understand this strange phenomenon we need to look at the eating habits of horses at both a biological level and at a behavioural level. Youre maybe thinking its cut and dry horses are herbivores arent they? Well it isnt that simple. 
Why would they want to eat a bird?
Horses are indeed primarily herbivores but they are also opportunistic eaters. They require a diet high in fibre and one that is densely packed with nutrients. When their diet falls short of these necessities they are inclined to feel hungry and when a horse feels hungry they are quite capable of thinking outside of the box in terms of foodstuffs. Should the opportunity arise this can mean chomping down on birds and even small mammals. This behaviour is however not a normal one. It isnt an acceptable means of a horse trying to attempt to correct the imbalance and is only indicative of a deficiency somewhere within their diet. Most likely if this is the cause there is some mineral or nutrient that is lacking in abundance. 
A bored horse might also eat a bird. Horses kept in confines too small or too uninteresting for them might turn to bizarre behaviours by way of keeping themselves entertained. One of the five welfare needs for all animals under the Animal Welfare Act 2006 is the need to exhibit normal behaviours. Normal behaviours for a horse include grazing roaming grassland and playing etc among others. One of the ways we potentially often necessarily limit their ability to be a horse is to stable them. As custodians