Spring is here, at last! The warming temperatures bring new beginnings as migrating birds travel north from their wintering grounds. Many of these birds stop in the southwest only briefly to refuel for longer journeys, whereas others stay in the area for the breeding season. The more commonly admired spring/fall or summer migrants in New Mexico and Arizona typically include hummingbirds, tanagers, warblers, and hawks. One of my favorites, however, is the underappreciated turkey vulture (Cathartes aura). The traits that make turkey vultures unappealing to most people make them truly fascinating to me. For starters, they are obligate scavengers, so they depend almost entirely on carrion (dead animals) for survival, and I love a resourceful species.
Quite a few of the behaviors and characteristics turkey vultures possess are associated with conserving energy given finding food sources can be unpredictable. One adaptation is having long, broad wings that aid in soaring long distances without expending much energy. Another is having a featherless head, which stays cleaner when feeding and assists with temperature regulation. Turkey vultures lower their body temperature at night to conserve energy which is why you have likely seen them sunning in the morning. They position themselves in the sunshine with their wings wide open to raise their body temperature back to normal. The species also thermoregulates by defecating on their feet, a behavior that even a turkey vulture enthusiast like me will admit is an off-putting way to cool down.
If you thought I was done describing all the “unpleasant” turkey vulture traits, I am not quite finished. Bird species use a variety of tactics to avoid threats. For example, burrowing owls mimic the rattling sound of rattle snakes to ward off intruders and dove species easily lose their feathers to evade the bite or grasp of a predator. The turkey vulture has a much more perplexing defense mechanism. Unfortunately, I have had the pleasure of witnessing it firsthand. It was a scorching hot and humid day in south Texas, and I was checking a remote camera trap set up at a wildlife drinker, a water trough birds and other wildlife can drink from. It was common for vultures to congregate at the drinkers, but they would usually fly off as I drove up. This particular day, I unknowingly walked up to the structure while a couple of vultures were still present. As soon as I was within a few meters, the birds quickly lifted off the ground. I was startled by the loud sound of their wings flapping and the splat of vomit hitting the ground. It took me a second to recognize what had just happened, but I remembered – turkey vultures throw up as a form of self-defense. As you can imagine, it was an unpleasant couple of minutes changing out the batteries and SD card in the camera as I tried to hold my breath.
Beyond these fascinating traits, the most remarkable characteristics of the turkey vulture are their keen eyesight and excellent sense of smell. These qualities allow them to detect and locate carcasses from long distances, within forested environments, and even under leaf litter. In fact, the species is thought to have one of the largest and most well-developed olfactory systems of any bird. Their sense of smell is so sensitive they can detect odors at a few parts per trillion. Turkey vultures have even been used to locate natural gas leaks. Companies add a compound, ethyl mercaptan, to odorless natural gas that humans can smell if there is a leak. Ethyl mercaptan is also produced as a biproduct of decomposition, and therefore turkey vultures locate natural gas leaks thinking they are going to find a meal. If you ever see vultures congregated near a natural gas pipeline, please notify the gas company.
Sadly, many vulture species are imperiled, but the turkey vulture is not a species of conservation concern. The turkey vulture has large, stable population numbers, and a widespread range, extending from southern Canada to the southernmost tip of South America. They occur in a variety of open and semi-open hab