Livestock and Carnivores: Economic and Ecological Interactions

Carnivores-livestock interactions cause human-wildlife conflicts worldwide. These interactions are present under a wide range of ecological and economic circumstances. This paper studies the relationship between predation mortality and natural mortality, when food availability affects natural mortality of the livestock. Semi-domestic Saami reindeer (Rangifer t. tarandus) herding in Norway is used as a case study. When predation affects reindeer density, food competition among reindeer changes, which changes weights and natural mortality in the reindeer population. An age-structured bio-economic model is presented, where this relationship is taken into account. While predation mortality may be additional to natural mortality in absence of food limitation, it can compensate for natural mortality in situations of food scarcity. Furthermore, due to density dependency in livestock weights, predation may increase the meat value of livestock. The paper analyzes how predation affects livestock production and economic performance under an optimized management scheme. One main result is that predation shifts the optimal harvesting composition towards calf harvesting and, therefore, the optimal stock composition among the different categories of animals. This contrasts findings in the existing bioeconomic literature. Furthermore, a changing harvesting pattern towards calf harvest is an important adjustment that highly limits the negative impact on profit of predation.