By: Jim Pauff, Travis Audubon Master Birder
In Asia and Africa vultures are in decline, because the drug Diclofenac, given to cattle, is lethal to vultures eating dead cows. Poisoned bait set out for predators also kills them. India lost ninety-eight percent of its vultures in some provinces. Worldwide, seventy-three percent of vulture species are declining. But North American black and turkey vultures are increasing. A study in an area of North Carolina in 2014 found black vultures increasing ten percent a year. Both turkeys and blacks are long-lived, intelligent, and sociable. They soar together an average of 535 to 375 feet up. Yet their personalities are different. Turkey vultures eat nothing but carrion. Black vultures are more aggressive.
Not long ago a university student told me that vultures hunt. He’d seen them kill small animals. Restraining myself, I smiled benignly down at him, as he was no doubt spouting a countrified Texas myth his grandfather told him. It’s good I kept my mouth shut because he was correct. Black vultures are sometimes predators. With a minor population explosion going on they are stirring up trouble in Illinois and Arkansas. Both states are discussing how to control them. They’ve killed deer at a deer ranch and lambs and calves up to two months old in pastures. It doesn’t happen often but it happens enough that farmers are complaining about it. The birds go after small animals’ eyes. After blinding them, they peck away at their rectums until they bleed to death. Those are the reports, anyway. Black vultures are audacious, the first vultures to appear in forensic “body farms” where scientists monitor human decomposition. Vultures recently ate a television actor in Oregon who was hiking and fell off a cliff into a tree. They ate his pug dog, too. The dog’s name was Boo Boo Bear. Requiescat in pace. It’s a good bet black vultures landed first to investigate the dead guy wedged in a tree.
On a lighter note, black vultures don’t soar as well as turkey vultures because they have heavier wing loadings; studies show they spend more time perched. Both are communal but blacks hang out together more. They famously don’t have a sense of smell. Instead, they keep their eye on neighboring turkey vultures which have extraordinary olfactory senses, and follow them down when they find something. Both are beneficial. After moving through their guts, bacteria for swine flu, botulism, and anthrax are killed. Home ranges of turkey vultures are twice the size of black vultures except during the breeding season (January through June), when blacks’ ranges enlarge and turkeys’ shrink a bit, presumably because of chick-rearing. Both ranges contract from June to October when food is plentiful. They enlarge again in winter and stay that way through the breeding season. Turkey vultures soar more during cold months when there are presumably less olfactory clues leading them to food. Vultures in forested areas spend more time soaring to find food than in agricultural areas—which explains the many vultures circling the Hill Country.