ASHEBORO, NC ­­— What to do when one threatened species is affecting another? Dr. Corinne Kendall, the North Carolina Zoo’s Associate Curator of Conservation and Research, narrowed that broad-based question into a detailed study as part of her Ph.D. dissertation at Princeton University.

High densities of elephants can lead to a decrease in woodlands and tree availability. As a result, elephants can potentially have a negative impact on tree-nesting birds of prey such as vultures. Dr. Kendall assessed the severity of this problem in an ecosystem critical to vultures, Masai Mara National Reserve, Kenya, and the findings are published in the current issue of the Journal of Avian Biology.

“We wanted to determine if tree availability was likely to have an effect on the nesting potential of African vultures,” says Dr. Kendall. “To answer this question, you first need to understand what types of trees vultures prefer, and then we used satellite imagery and random sampling of trees in the Mara to estimate how many trees might be available for nesting vultures.”

By gathering data on more than 100 nests for three species of vulture, it was possible to understand what vultures need to nest successfully. Then by calculating both how many trees would meet these criteria and how many birds might be wanting to nest in a given year, it was possible to assess if tree availability could be a limiting factor for nesting vultures.

“The results were striking,” says Dr. Ara Monadjem, a professor at the University of Swaziland and co-author of the study. “There are thousands of more trees available than there are potential breeding vultures in the Mara-Serengeti ecosystem. So declines in tree availability are unlikely to be affecting these endangered birds.”

So at least in this area, elephant populations are unlikely to be affecting vultures, notes Dr. Kendall. “Sadly, despite the plethora of potential nesting trees, African vultures are still in trouble,” she says. “People continue to use poisons to kill predators like lions and hyenas and often end up killing vultures as well. Vultures and elephants also have common enemies, as elephant poachers use poisons to reduce vulture populations as these scavenging birds can help rangers find large carcasses, like those of dead elephants. So there may be more than one angle to the unusual connections between elephants and vultures.”

For further information, contact Dr. Kendall at   


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