Culling is the act of selectively killing animals for population control. For the first time, researchers have shown that the effects of these mass killings can last for decades.
It might not seem obvious when looking at an elephant population, but social interactions and responses to cues are severely damaged in groups that have survived a cull. These interruptions in social development have the potential to cause long term damage for these intelligent animals. The damage incurred by the elephants may also apply to other intelligent species, including chimps and cetaceans.
Humans have selectively killed animals for a very long time in order to control livestock and wildlife populations. For nearly thirty years until 1995, culling was standard practice to control elephant populations in Kruger National Park in South Africa to preserve the landscape and vegetation, as elephants require a large amount of plants to eat each day.
In the late 1990s, scientists learned that the process negatively affected elephants, but it was thought to be similar to post-traumatic stress disorder (PTSD) because of the atypical behavior reported afterward. Orphaned males killed over 100 rhinoceroses in a 10 year time span, which had never been seen before. Some of the orphaned females even attacked tourist jeeps and were much more aggressive than normal. This has been attributed to a lack of social learning, because the older females who teach the young proper behavior had been eliminated. While some of the elephants were rehabilitated, they still exhibited traits that were outside the norm.
To conduct this study, a population of elephants from Amboseli National Park in Kenya, which has not been largely affected by culling, was compared to the population from South Africa’s Pilanesberg National Park, which was established with orphans from Kruger National Park during the 1980s and 1990s. The ability to understand social cues was measured in these animals by playing recordings of an older, dominant female issuing greetings and warnings of danger.
While the Pilanesberg group looks to be doing well on the surface, scientists say that the population is far from alright. When confronted by a recording of a strange female who could pose harm to the group, there was almost no uniform response. In contrast, the Amboseli elephants all recognized the potential danger and froze where they were standing in order to assess the threat. They then grouped together and were led by the matriarch to go in search of this other potentially dangerous female.
According to the scientists, it wasn’t that the Pilanesberg group was more accustom to associating with elephants from outside of their family, but they simply hadn’t been taught what to do when confronted by a more dominant strange female.
Because elephants typically live for 70 years in close groups led by a matriarch, the Pilanesberg population is at a severe disadvantage. The females who were orphaned at a young age and were not taught what to do will not be able to teach future generations how to handle potential threats. This could pose a severe risk to the longterm survival of the Pilanesberg elephants. In light of this research, researchers hope that officials will understand the full weight of culling before selectively killing elephants again.