By Robin Meadows
Protecting charismatic top predators is a common strategy for conserving biodiversity, but does it really work? New research shows that the answer is yes for birds of prey in the Italian Alps. Sites where raptors breed have the greatest diversity of birds, butterflies, and trees. This is one of the few quantitative studies on whether protecting top predators is a valid approach to conservation.
“Conservation based on top predators can be ecologically justified because it delivers broader biodiversity benefits,” say Fabrizio Sergio of the Estación Biológica de Doñana in Seville, Spain; Ian Newton of the Centre for Ecology and Hydrology in Huntingdon, U.K.; and Luigi Marchesi of the Trento Museum of Natural Sciences in Italy in Nature.
The researchers compared biodiversity at four types of sites in the Italian Alps: raptor breeding sites, similar sites where raptors did not breed, breeding sites of birds that are not top predators and are generalists, and breeding sites of birds that are not top predators and have specialized ecological requirements. They considered five species of raptors that represented a range of habits (nocturnal or diurnal), breeding habitats (forest, woodland, or grassland), and diets (arthropods or birds and mammals). Bird, butterfly, and tree diversity were used as measures of biodiversity.
The researchers found that the top predator breeding sites had the greatest abundance and diversity of the birds, butterflies, and trees surveyed. Notably, the raptor breeding sites had nearly twice as many bird species. “Sites occupied by these predators are consistently associated with high biodiversity,” say the researchers.
Next, the researchers used a model that selects a network of reserves that maximizes biodiversity while minimizing the number of protected sites. Of the four types of sites considered, networks of raptor breeding sites had the most biodiversity in the least number of sites. On average, the “top predator” networks had more than 90 percent of the total biodiversity, whereas the “non-top predator” networks had only about 70 percent of the total biodiversity. “The efficiency of each protected-area system was higher for top predator sites,” say the researchers.
While some conservationists have recently argued that protecting top predators is not a good way to protect overall biodiversity, the authors of this study counter that “More information from other systems will be needed before the powerful top predators can be dismissed from the conservation arena as unscientific tools.”
Sergio, F., I. Newton, and L. Marchesi. 2005. Top predators and biodiversity. Nature 436:192.
Photo by F. Sergio and V. Penteriani
