September 13, 2019
The Virtue of Vultures
Posted by: Rock Delliquanti
Story by Rock Delliquanti : Photos by Phil Murdaco (@phillipmurdaco on Instagram)
In 2005 a television show aired on the Discovery Channel called Dirty Jobs. The goal of the show was to put a spotlight on the jobs in society that are strange, messy, and oftentimes incredibly important while being underappreciated. Every episode these hard-working people would shock and amaze viewers when they saw what needed to happen for the rest of society to stay functioning and clean. This show focused on people around the country, however an entire series could be devoted to the countless organisms around the globe that have their own “dirty jobs.”
One of these groups of organisms that deserve recognition for going above and beyond in our messy world are vultures. Vultures are typically an underappreciated family of birds because they are “ugly,” because they have behaviors people typically find “gross,” and because they have negative superstitions said about them. Despite all of this, vultures provide an invaluable service to the ecosystems they inhabit and without them the world would be a lot grosser and a lot more dangerous.
Vultures are obligate scavengers--meaning they only feed on dead things they did not kill--and feed primarily on animal carcasses. Vultures have several adaptations to help specialize them for this scavenger lifestyle. To start off, vultures locate potential food sources by soaring on columns of hot air called thermals. By utilizing their massive wings, vultures can stay airborne for long periods of time with very little energy usage. Once airborne, vultures will use their senses to key in on food. Turkey Vultures (Cathartes aura), for instance, have a particularly impressive sense of smell which allows them to detect trace amounts of ethyl mercaptan. This chemical is produced by animal decomposition and as it drifts upward, Turkey Vultures home in on this smell and located the carcass even if it is hidden under vegetation. Black Vultures (Coragyps atratus), however, do not have an olfactory lobe as powerful, and so they will often just follow Turkey Vultures to carrion. Once the more social Black Vultures start to outnumber the more solitary Turkey Vultures, the Turkey Vultures concede their meal to them.
Once their food is located, vultures of all types will begin to consume the carcass and along with the bacteria that have been developing on it. To combat the potential pathogenic bacteria inhabiting the carrion, vultures have developed powerful stomach acid which allows vultures to handle hazardous pathogens. These vultures can tolerate incredibly dangerous bacteria, such as the microbes that causes anthrax, botulism, and hog cholera, which helps prevent their transmission into the local ecosystems. Their featherless heads help minimize these bacteria from accumulating on them when they are feeding. They also engage in urohidrosis where they defecate on their legs to cool themselves off and to help clean off leftover carrion they may have stepped in.
All of these evolutionary tools assist with finding, consuming, and processing carrion so that no one else has to deal with it and risk potential exposure to harmful microbes. The New World Vultures can be found over the majority of North and South America which shows the high demand for their ecosystem services. Their abundance and behaviors, however, are partially why vultures have been thought of as bad omens. Their featherless heads and raspy growls can be unsettling to behold, especially when a committee of vultures looms in a dead tree or is feeding on carrion, and it has unfortunately given them a negative connotation in people’s minds. However, it is important to recognize that they are built for a dirty job and they do it spectacularly.
Birds are often given names that are related to their life history, and vultures are no exception. The word “vulture” is likely to be derived from the Latin word “vellere” which means “to tear, to pluck.” But what is more fitting for these birds is their scientific names. The family of New World Vultures is Cathartidae which comes from the Greek root “kathaírō” which means “to cleanse, to purify.” Catharsis shares the same root, and it feels fitting for these birds to be seen as purifiers. In some Cherokee legends, vultures are referred to as “peace eagles” because they never kill anything to eat; additionally, in ancient Egypt vultures were seen as symbols of rebirth by consuming death and producing life from it. And while vultures may not win any beauty contests, they are an irreplaceable member of the hard-working clean-up crew our world needs to stay happy and healthy.