Avian Infrastructure

Vultures[Image: The turkey vulture’s “verification flight pattern,” taken from “The Role of Olfaction in Food Location by the Turkey Vulture” by Kenneth E. Stager (PDF)].

In an article for New Scientist last year, I wrote about the expansion of urban infrastructure to include animal life, from pigs serving a de facto waste-management role in cities such as Cairo to falcons being used to patrol a Santa Monica business park against, less welcome species.

It was thus interesting to read last night that the noxious smell artificially introduced to otherwise odorless natural gas was originally added, at least partially, because it would attract turkey vultures.

In a 1964 paper by Kenneth E. Stager called “The Role of Olfaction in Food Location by the Turkey Vulture” (PDF) we read that the “decision to conduct field tests with ethyl mercaptan (CH3CH2SH) as an olfactory attractant for turkey vultures came as a result of conversations with field engineers of the Union Oil Company of California.” Its purpose would be “to aid in locating leaks in natural gas lines”:

It was suggested to them by a company engineer in Texas that an effective way of locating line leaks in rough terrain was to introduce a heavy concentration of ethyl mercaptan into the line and then patrol the route and observe the concentrations of turkey vultures circling or sitting on the ground at definite points along the line… A high concentration of ethyl mercaptan was introduced into the forty-two miles of gas line and a traverse of the route was made. At several points along the line, turkey vultures were observed either circling or sitting on the ground. At those locations the odor of the ethyl mercaptan was very pronounced and examination of the line revealed the leaks.

There are at least two things worth highlighting here: one is the strange image of 20th-century oil company employees wandering through “rough terrain” in coordinated synchrony with families of turkey vultures, in effect bringing avian labor into the international supply chain of petroleum products.

It’s the turkey vulture as corporate companion species: a living being enlisted for assistance in shepherding—or flocking, as it were—natural gas to the final customer. It seems almost medieval.

But the second thing that seems worth commenting on is the broader implication that natural gas was made to smell like death—to smell like rotting corpses—thus becoming attractive to flocks of turkey vultures. This brings to mind Reza Negarestani’s book, Cyclonopedia, where Negarestani refers to the oil industry in only somewhat fictional terms as a kind of industrial cult organized around what he calls “the black corpse of the sun”: that is, oil, with all of its volatile by-products, the remnant hydrocarbons of once-living things, transformed through millions of years of burial.

That we would make petroleum gas smell like dead animals seems almost perfectly ironic, giving this image of necromantic Union Oil employees out scouting the backlands of Texas and California looking for gas leaks, following airborne animal trails, an even more bizarre interpretive bearing.

(Vulture anecdote originally spotted on Twitter, thanks to a retweet from @carlzimmer).