A new study shows that there is substantial disagreement among scientists on the number of species of birds, which prevents accurate decision making for prioritizing conservation efforts. The study, “Toward reconciliation of the four world bird lists: Hotspots of disagreement in taxonomy of raptors,” uses birds of prey as an example for why this problem requires immediate resolution. Birds of prey represent approximately 5.5% of the world’s bird species, but are significant in this discussion because roughly 52% of raptors have declining global populations.

The lead researcher for this effort, Dr. Chris McClure of The Peregrine Fund says, “A place may or may not be deemed a priority for protection depending on the number of recognized species in the area. So we decided to compare the four most widely used world bird lists that scientists use and found that, among raptors, there was only 68% consistency in the species recognized across all four lists. That’s not very consistent and could lead to confusion among conservation practitioners and government agencies.”

The four most widely used lists for recognized bird species include 1) the IOC World Bird List which is used by the international ornithological journal IBIS, 2) the Howard and Moore Checklist of the Birds of the World, which is used by several major museums around the world, 3) the eBird/Clements Checklist of Birds of the World, which is used by the Cornell Lab of Ornithology in the implementation of all of their programs, and finally 4) the Handbook of the Birds of the World and BirdLife International Digital Checklist of the Birds of the World, which is followed by BirdLife International when determining the Red List of Threatened Species and for several international agreements.

McClure adds, “If this all sounds a bit confusing, that’s because it is. In fact the differences between the four world bird lists was recently referred to as ‘taxonomy anarchy.’”

Dr. Jeff Johnson of the University of North Texas’s Department of Biological Sciences explains the problem from a conservation perspective, “Typically conservation efforts are focused on saving species, however subspecies can provide considerable genetic and ecological diversity.” Take the Cuban Kite, for example. This is a critically endangered raptor, but only considered a species on two of the four lists. The other two identify it as a subspecies of hook-billed kite, which is not considered to be threatened with extinction. While its current numbers are dangerously low, “losing the Cuban Kite entirely due to extinction would be a travesty,” according to Johnson. “Consistent recognition of the Cuban kite as a distinct species could help elevate its prominence and thereby increase efforts for its conservation.”

Dr. Thomas Schulenberg of the Cornell Lab of Ornithology states, “In this study we looked at the ‘hotspots of disagreement’ between the four lists. We found that there’s a lot of disagreement about owls, particularly in southern Asia. More broadly, the classification of raptor species is not well aligned across the high diversity regions of Indonesia, India, and China.”

Dr. Denis Lepage of Birds Canada says, “The bottom line is that, if we want to conserve birds, including raptors, working together to develop a single world bird list would go a long way.”  According to McClure, efforts are now being discussed to consolidate the four lists, but no official announcement has been made concerning when that may happen. “Oftentimes, taxonomic research is not well funded,” lamented Lepage, “but this study demonstrates that a concerted effort is critical for conservation of biodiversity. This is too important to not give our best effort.”

This study was a collaboration between the University of North Texas, Birds Canada, Boise State University, Ornithologi, Southern Cross University, Cornell Lab of Ornithology, Michigan State University, and The Peregrine Fund.