In Australia's Western Desert, Aboriginal hunters use a unique method that actually increases populations of the animals they hunt, according to a study co-authored by Stanford Woods Institute-affiliated researchers Rebecca and Doug Bird. Rebecca Bird is an associate professor of anthropology, and Doug Bird is a senior research scientist.
The study, published Oct. 23 in Proceedings of the Royal Society B, offers new insights into maintaining animal communities through ecosystem engineering and co-evolution of animals and humans. It finds that populations of monitor lizards nearly double in areas where they are heavily hunted. The hunting method - using fire to clear patches of land to improve the search for game - also creates a mosaic of regrowth that enhances habitat. Where there are no hunters, lightning fires spread over vast distances, landscapes are more homogenous and monitor lizards are more rare.
"Our results show that humans can have positive impacts on other species without the need for policies of conservation and resource management," Rebecca Bird said. "In the case of indigenous communities, the everyday practice of subsistence might be just as effective at maintaining biodiversity as the activities of other organisms."
Martu, the aboriginal community the Birds and their colleagues have worked with for many years, refer to their relationship with the ecosystem around them as part of "jukurr" or dreaming. This ritual, practical philosophy and body of knowledge instructs the way Martu interact with the desert environment, from hunting practices to cosmological and social organization. At its core is the concept that land must be used if life is to continue. Therefore, Martu believe the absence of hunting, not its presence, causes species to decline.
While jukurr has often been interpreted as belonging to the realm of the sacred and irrational, it appears to actually be consistent with scientific understanding, according to the study. The findings suggest that the decline in aboriginal hunting and burning in the mid-20th century, due to the persecution of aboriginal people and the loss of traditional economies, may have contributed to the extinction of many desert species that had come to depend on such practices.
The findings add to a growing appreciation of the complex role that humans play in the function of ecosystems worldwide. In environments where people have been embedded in ecosystems for millennia, including areas of the U.S., tribal burning was extensive in many types of habitat. Many Native Americans in California, for instance, believe that policies of fire suppression and the exclusion of their traditional burning practices have contributed to the current crisis in biodiversity and native species decline, particularly in the health of oak woodland communities. Incorporating indigenous knowledge and practices into contemporary land management could become important in efforts to conserve and restore healthy ecosystems and landscapes.
The study was funded by the National Science Foundation.