This tug-of-war for territory and resources is just one manifestation of the growing tensions between economic development and environmental conservation, and today we have two papers, from two continents, that provide new information about how we might be able to strike the right balance between sometimes conflicting development goals.
The first study compares the behavior of Asian elephants in fragmented versus non-fragmented forests in Borneo. Using a satellite tracking program to monitor five female elephants, the researchers found that the home range, or the area covered by a wild animal over the course of a year, for elephants in non-fragmented forest was approximately 250 to 400 square kilometers. When the forest was fragmented, though – primarily by human developments such as roads, farms, and villages – the home range nearly doubled, to about 600 square kilometers.
The authors, led by Raymond Alfred of Sabah University of Malaysia, suggest that the significant increase in the home range could reflect increased difficulty in satisfying food and water needs in a highly fragmented environment. Their results could possibly help alleviate some of this elephant stress by providing guidelines for determining how much space is needed for long-term elephant preserves.
Using such guidelines could also help control elephant crop raiding, which has become a major problem in both Asia and Africa. As people move into elephant habitat, elephants have begun sampling their crops to enrich their diet – leading farmers to sometimes kill the thieves, which is particularly concerning given the conservation listings for both Asian (endangered) and African (vulnerable) elephants.
There has been some work to develop methods to protect both the elephants and the crops, including installing “beehive fences” as deterrents (see this paper for more information about the surprising relationship between elephants and bees), but today’s paper, led by Patrick Chiyo of University of Notre Dame, takes a different angle, looking at what can cause an elephant to initiate crop-raiding behavior.
Crop raiding is known to be more common among male than female elephants, so the team investigated the raiding behavior of male African elephants in Amboseli National Park in Kenya. Out of about 365 male elephants, they identified 43 individual crop raiders, and estimated that there could be an additional 40 perpetrators who remained undetected. In other words, about 20% of the male elephants may be raiders. Males at their reproductive peak were nearly twice as likely to raid, and the authors suggest that his behavior could be due to increased energetic needs for mating, or increased risk-taking behavior associated with their age.
Furthermore, the elephants were more likely to raid if their elephant “friends” were raiders as well. It’s not all about peer pressure though – the effect gets stronger the older the raider friends are, suggesting that the elephants are actually learning from their older, wiser companions. This implied intelligence should come as no surprise, given all the evidence for elephant smarts (see, for example, this study on elephant learning) – and it makes me think that, conservation concerns aside, elephants might have something to teach us about respecting our elders.
Image source: brittanyhock on Flickr