Trophy Hunting Effects on Ungulates Overestimated
The Journal of Wildlife Management published another update to the question of a hunters influence on their prey.
Previous studies claimed that trophy hunting had significant consequences for Big Horn Sheep herds. Several studies observed phenotypic declines correlated with hunting pressure, most notably horn and body size following intensive trophy hunting. But new research calls into question the correlation between phenotype and hunting pressure without taking environmental conditions into account.
The new study conducted by James Heffelfinger of Arizona Game and Fish reviews a wide swath of literature associated with human-influenced evolution. The original studies observed that when trophy hunters removed the largest horned animals from an isolated population of sheep, a decline in relative body size resulted. The authors concluded that trophy hunting must be the primary driver of horn size decline. This was the damning evidence for ‘directional selection’ that subsequently created a media frenzy. James’ new study combats the assumptions made in the original findings by pointing out that the study failed to consider alternative factors that may have led to the reduced horn size, or even if the reduction was happening at all.
It is reasonable to suggest that given the circumstances, an isolated population of animals could experience negative effects of trophy hunting. The original study conducted by David Coltman over a thirty year period was impressive to say the least, but the degree of backlash within the scientific community is especially notable. The primary complaint levied against the Coltman study has been the lack of the attention given to environmental conditions. David Coltman subsequently published a study that acknowledged his lack of consideration for nutritional or environmental factors in his original analysis.
Trophy hunting has been shown to negatively impact endangered species populations, as this study documents in Africa. But it has also been shown to improve at risk populations and help impoverished communities. As conservation continues to grow in importance around the globe, it is equally important to produce strong evidence.