Raptor species around the world are in trouble, according to a new review of conservation data by two major wildlife groups.

The International Union for the Conservation of Nature and Birdlife International collaborated to do a new analysis of bird population data for 557 of the currently recognized species of raptor – birds like hawks, eagles, falcons, owls, and vultures. They found nearly a third of those species to be endangered at some degree and over half of raptor species to be on the decline. Eighteen species are critically endangered, such as the Annobón scops owl native to Equatorial Guinea, with fewer than 250 remaining, or the hooded vulture from sub-Saharan Africa, currently undergoing major habitat loss due to rising temperatures.

Other species are locally extinct, or close to it, in specific regions where they once flourished. Locally extinct means that they no longer play their role as apex predators in those places, which can cause a cascade of changes to the food chain of a region. A common one is massive overpopulation of prey animals, which will usually result in either the spread of disease through a prey species, potentially wiping them out, or over-grazing of plant species in the area.

The largest threats to bird species are climate change and habitat loss, which often go hand in hand, and toxic substances. As apex predators, raptors are particularly susceptible to chemical use that may penetrate the food chain, just as humans are at risk from mercury in fish. The near-eradication of the bald eagle and peregrine falcon in the U.S. in the 1960s due to DDT is a classic example, and not even the most dramatic. An anti-inflammatory drug used on cattle in Asia may be to blame for the loss of nearly 95 percent of vultures in agricultural areas there.

According to conservation groups, few sites critical to raptor species are protected. Birdlife International identified 4,200 such sites worldwide.

Photo: Two hooded vultures sit in a withered tree in the Gambia. Credit: Shutterstock