We were having a talk about vultures at lunch, my kids and I. The older one made a statement like, “no one wants to see vultures,” and the little one wanted to know why. It was postulated that seeing a high number of vultures could be an indication that something is wrong with the environment.
As it turns out, it might be the other way around, for it is the decline of vultures in other areas that may actually demonstrate a natural imbalance. While it is true that in North America, we have made the world a better place for vultures (by the increase in roadkill and decrease in vulture persecution by farmers), this is not a boon seen across the board. In fact, in India, the vulture population decreased by 99% by 2008, leaving very little of these large, although unsightly, incredibly useful birds.
Of all the reasons why these large carrion eaters have been reducing in such significant numbers in India, the biggest reason is the use of Diclofenac, which is a painkiller administered to cattle. The cattle carcasses were a large part of the diet of vultures in that area, and the painkiller was poisoning the birds. The birds do not have a critical enzyme needed to break down the medication and die within three days of renal failure after consuming this meat. The use of this drug was banned in 2006, and numbers show a slight increase between 2011 and 2012, so that is good news. DDT has also played a role, as this pesticide was dumped in high quantities in a national park in order to quell malaria rates. High levels of DDT were being found in the flesh of cows, left for vultures to feed on due to Hindu practices regarding the revered cud chewers.
However, it is not just India that has seen a significant decrease in vulture population. Nepal shares many of the same reasons for decline of the vulture population within its borders as India. Africa has also seen its fair share of vulture decline, also due in some part to the use of Diclofenac, but also due to the use of a pesticide called Furadan that farmers lace carcasses with to reduce herd loss from carnivores. Since each carcass can feed up to 150 vultures, this leaves a huge unintended consequence of the dying off of these useful birds. Some of the deaths are also attributed to the use of vultures by shamans in mystical ceremonies that commonly involve the use of this animals brain in ceremonies. It is believe that the vulture brain (either through smoking, eating, or smearing on the body) imbues on the recipient powers of clairvoyance or increased intelligence. The black market sale of these birds leads to the disappearance of roughly 59,000 birds a year.
In the US, we have also had our losses over the years. During 1946-1970, vulture numbers dropped off, like the other large birds of prey, due to the widespread use of DDT. This pesticide was discovered to thin the shells of these big birds, decreasing the ability of the offspring to survive. However, since the use of this has been banned, the numbers have rebounded, and it seems like here in Texas, you can’t hardly look at the sky without seeing one floating about.
I think it is interesting to note that before 1920, the ubiquitous Black Vulture was not common to Texas. It was not until a change in agricultural practices that they became permanent residents. The truth is also that the vulture population follows the white deer population. Since Texas has the largest population of white tailed deer of all the states, it makes sense that we would also see high numbers of vultures here.
So in our case, seeing the vultures IS something we want to see, because it indicates the health of the system, not the other way around, like we speculated at lunch. It means our wildlife is flourishing, and that pesticides (at leas those that affect the birds) are not leaking into the environment at such levels that they are having an impact on population levels, that our farmers aren’t leaving laced carcasses meant to discourage large predators, and that we don’t eat their brains.
It could just be, though, that no one wants to see the vultures because they are just not attractive birds. Their heads are bare to keep them clean when eating carcasses, but it makes them look funny. They don’t have flashy colors to their feathers, and their eating habits make us feel disgusted. However, they perform a useful task in cleaning up the environment of the collective dead things. Without them, the risk of disease spread goes up.
If you don’t believe me on this, ask India. They now have issues with increasing feral dog populations and water contamination from their lack of vultures.
I myself find the vultures boring and commonplace, but after today’s research (what better way to spend a non-snow snow day), I understand why there are so many of them, and it makes me feel comforted.