Some forms of behavioural interactions between organisms and their living environment can be adaptive. When an adaptation is successful, animals improve their individual fitness. It is well established that adaptive behavioural changes that relate to avoidance of predators in herbivores can reduce the likelihood of predation, whereas adaptive changes that relate to diet can improve rates of growth and development. Both forms of adaptive behavioural changes affect the fitness of individuals and can shape the size of herbivore populations. Numerous studies have shown that predation and diet influences foraging herbivore behaviour.
More recently, there has been growing awareness of the importance of parasite burden as an additional driver of fitness in herbivore populations, which can also influence behavioural adaptations in herbivores. Although there is an inevitable relationship between predation, diets and worm burden, few examples display that evidence. This could be because all three factors (predation, diet and worm burden) are present in some studies attempting to characterise adaptive behavioural choices, which makes the research analysis more complex.
Feral horses are a good model to study as predation does not occur, which removes one factor and makes the research process easier.
The aim of this study will be to compare the dietary choices of two sympatric but isolated horse populations on their parasite burden, where the main hypothesis is that components of the diet do influence parasite load in natural populations of herbivores, horses.