Arrival of turkey vultures an unlikely harbinger of spring
You can hear it in the morning air. The songs of spring are starting to leak through the dark veil of late winter. The cardinals are singing again and the titmice are starting to join the fugue, beautiful signs that winter is losing her grip and we will soon be in the warm embrace of spring.
One of the most interesting signs of the change of season is the return of the turkey vulture (Cathartes aura). An odd harbinger, no doubt, the turkey vulture seems to faithfully show up about the same time as the landscape starts melting. So what do we know about these remarkable birds?
Well, the genus name “Cathartes” is only slightly altered from the original Greek “kathartes,” which means “a cleanser.” This is certainly a reasonable name considering the turkey vulture’s ecological role as a scavenger. The bird’s species name “aura” is unusual in the sense that its origin is neither Latin nor Greek. Instead, the word “aura” is from the Mexican Indian name “auroua,” which is used for the turkey vulture.
Despite any superficial resemblance to the Old World vultures of Africa and Eurasia, our turkey vultures are not close relatives. Instead, the turkey vulture, black vulture, and even the California condor are more closely related to storks. If I were to ask my biology students to explain this similarity between the two groups, I would expect them to discuss something called “convergent evolution.”
This occurs when very different animals try to make a living in a very similar way. A similar lifestyle produces similar challenges and the organisms will randomly happen upon the same solutions to common problems.
In the absence of any large avian scavengers here in the New World, some storks started to specialize on the consumption of carrion. After millions of years of trial and error, evolution produced specialized birds with a lot of the same adaptations as the Old World vultures; no feathers on the head, strong beaks, and an outstanding sense of smell (a rarity for birds).
Turkey vultures prefer fresh food, but freshly dead animals aren’t always easy to find in a part of the world that is largely forested. So, a sense of smell will allow the birds to home in on a dead animal.
Resistance to germs
They also possess an amazing resistance to the bacteria and other toxins that can be found growing inside rotting carcasses. Even baby vultures, which feed on regurgitated carcass parts, can withstand the nastier meals their parents bring them.
The vultures are here now and will stay in our area until the second week of November. Pairs of turkey vultures will be out searching for nice, quiet places to lay their eggs. Turkey vultures do not build nests. Instead, they look for ledges or cliffs where they can lay their eggs directly on the ground. Vultures also hide their nests very well because the powerful smell of rotten meat will give away the position of the nest otherwise.
Incubation of the eggs can take up to six weeks, while the rearing of the chicks (of which there are usually two) can take up to three months. Once they are old enough to fly, the youngsters are easily distinguished from their parents by their gray heads.
For now, however, we can focus our attention on simply spotting these wonderful birds as they turn in lazy circles over the spring landscape: sure signs of the coming spring.
Bill Danielson is a professional nature photographer and author living in Altamont. Contact him at www.speakingofnature.com.