CAN VULTURES AND AIRPLANES SHARE THE SKIES?

by Whit Gibbons

October 5, 2014

California condors are one of the world’s most endangered birds. They are also one of the largest. The wing span of these magnificent scavengers is more than 9 feet. Over 400 live in the wild today. Only 27 were known to be alive in 1987.

Amanda Holland, who worked in the USFWS California Condor Recovery Program as an intern, knows more about condors than anyone else I know. Now at the University of Georgia’s Savannah River Ecology Lab, she conducts graduate research on the condor’s eastern counterparts, vultures.

Vultures, aka buzzards, are nature’s sanitation engineers. As carnivorous scavengers, they forage on dead animals.

They also play a critical role in contributing to health safety by reducing the spread of some animal diseases, including rabies and anthrax.

Vultures clean up the landscape by eating, hence removing, what would otherwise become rotting carcasses. The eastern United States is home to two species.

Both species have bald heads, which allows them to tear meat from a carcass without fouling feathers around the mouth or head. However, the two differ in many ways.

The larger species, the turkey vulture, has an extensive geographic range, from southern Canada to the tip of South America. Turkey vultures are one of the few birds with an excellent sense of smell, a useful trait for an animal interested in homing in on blood or other smells of death.

A turkey vulture can locate a dead deer even when it is hidden under dense forest canopy.

The other native species, the black vulture, ranges from the southern United States to South America. They have no sense of smell, so when a black vulture is found scavenging a carcass in the woods, chances are it followed turkey vultures to the site.

Amanda’s research focuses on the movement patterns and ecology of these two southeastern vultures. One reason to study vulture movements is because of potential conflicts with humans, including safety and economic impacts on the airline industry.

The overall numbers and populations of vultures are increasing throughout the Southeast, and because vultures commonly roost and forage near areas associated with people, interactions between humans and vultures are likely.

Highways, landfills and cell towers are sites that may attract vultures. These birds will not attack you. But if a turkey vulture with a 5-foot wing span takes off from the side of the road and accidentally flies into your windshield, it is a lose-lose situation.

A one-to-one encounter with a vulture on a highway can be extremely dangerous. Amanda is investigating even more far-reaching safety hazards.

According to her, “Black and turkey vultures are major causes of bird-strikes ... and are ranked the second and fourth most hazardous species to civil aircraft due to the extent of damages they cause when involved in bird-strikes.”

Amanda has already trapped 295 vultures and marked them with individual identification numbers that are visible on their wings.

To further determine movement patterns, she has 16 tracking devices that record the exact location of particular birds as frequently as once a minute.

She will also be testing the effectiveness of a specially designed loudspeaker device as a nonlethal method to discourage vultures from inhabiting airfields and other areas where they could pose a safety hazard to humans.

Although American vultures in the Southeast are doing well enough to cause air traffic concerns, Amanda notes that more than 60 percent of vulture species are currently threatened with extinction globally. “In India, vultures are ecologically extinct. Populations have plummeted so drastically that they no longer provide measurable ecosystem services.”

This is not trivial. “Higher numbers of rats and feral dogs scavenge [on] carcasses when vultures are absent. Human health concerns have worsened and rabies cases have skyrocketed” in India.

Amanda’s study is an ideal mix of basic ecology with application to real-world problems. Perhaps her burgeoning knowledge base on American vultures will be applicable to some of the world’s species in decline.

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