The “cobra effect” is a type of perverse incentive. The effect occurs when a solution actually worsens the problem it is trying to solve. Named for a supposed bounty program that went awry in colonial India, there are many examples of incentives that lead to more of the very thing that should be reduced.
Interestingly, when you search for cobra effect, the other top examples all concern animals — an attempt to decrease the rat population in colonial Hanoi, Vietnam and an attempt to reduce the number of feral pigs in Georgia. This is strange because these animal-related problems all contain the solution within themselves.
If you read about these examples, you’ll learn a bit (and often just a bit) about the history of each time and place. But what you won’t read is how these incentives could have been aligned with their intended outcomes. In this post, I propose some changes that the designers of these incentives could have used so that they might have actually gotten their desired outcomes.
The Cobra Bounty Bust
Cobras are not a good animal to have where there are people. And it’s understandable why a government would want to reduce their numbers, as was attempted by the British colonists in India. To combat these venomous snakes in human-populated areas, the British decided to offer a bounty for dead cobras or cobras skins.
The intent of the Indian cobra bounty was not to grow the number of dead cobras. After all, once the initial killing of wild cobras was achieved, finding cobras to kill would become more difficult. But since the bounty rewarded dead cobras, the best way to continue to produce those dead cobras was by raising them with the purpose of killing them for the bounty.
The actual intent of the cobra bounty was to reduce or even eradicate cobras entirely. The intent was fewer (ideally no) cobras living in Delhi, not more and more dead cobras. There’s a difference. So how could the cobra bounty have been enacted to avoid its abuse — that is, the cobra farms that emerged? The answer is wrapped up in the problem itself.
Cobras reach maturity between the age of four to six years. One way to avoid the bounty misuse would be to only pay for adult cobras, as determined by weight or length. In other words, people who wanted to abuse the bounty would need to raise the baby snakes for years before they could receive payment. It probably would not be worth it. This does punish people who legitimately encountered a nest of snakes, but it’s an option.
Another more effective way would be to run the bounty for short lengths of time or to end the bounty periodically and without notice. The first end to the bounty, say one month into the program, would be before anyone got the idea to breed the snakes. Breeding snakes is an investment of its own. Different cobra species have different egg laying habits, but in general female cobras lay eggs only once per year (approximately nine weeks after mating) and it takes the eggs 45 – 80 days to incubate. If the bounty program only runs for a month at a time and starts and stops at unpredictable intervals, then there is no way to plan cobra production to take advantage of it. The key is that officials also don’t want that first group of bred snakes released into the wild. That means that the bounty should be ended within the first month, before cobra breeders could do their work.
Another way would be to estimate the costs of raising cobras to maturity so that the bounty could be set lower than that. When it only makes sense to kill wild cobras people will not bother to raise them.
The above ideas are with the understanding that at the time, it was not possible to import snakes from another region to arbitrage on the cobra bounty. Today, that might be possible.
(Note: Though this story has been covered by everyone from Freakonomics to The Hindu BusinessLine, I was not able to find the original documents that detailed this situation in colonial India… I believe it never happened! Let me know if you have a primary source.)
Oh, Rats
The Governor-General of Indochina, Paul Doumer, arrived in French Indochina in the late 1800s and set about making Hanoi a modern city. One goal was to eradicate the enormous rat population. Again, these intentions backfired. A great read on this is Of Rats, Rice, and Race: The Great Hanoi Rat Massacre, An Episode in French Colonial History, by Michael G. Vann.
Colonial Vietnam’s new French Quarter was modern, had wide avenues, and grand houses (I only visited once in 1998 and it was beautiful even then). The sewers in the French Quarter were good and apparently did not overflow after rain like those in the local quarters. But it’s interesting that the French apparently became concerned with rat eradication after it was understood that rats were entering French homes through the sewer system and importantly, that rats were vectors for bubonic plague. This was discovered only in 1894.
French colonists had local Vietnamese go into the sewers to hunt rats and paid them for turning in the dead carcasses. But hunting rats in sewers is one of the worst jobs I have ever heard of and people did not want to do it. The first encouragement was to increase payment from one cent to two cents per rat in 1902, then to four cents by 1904. Then came the other crucial change. Rat hunters no longer had to hand in the entire rat carcass. Just the tail was sufficient.
It wasn’t long before rats without tails were found running around. And also not long before residents were found raising rats. As with the cobras above, after the initial decline in the population of the undesired pest, the population increased.
I do not know why poison or traps were not used instead of human rat catchers. Poison was being used at least 50 years earlier in England. There is a fantastic account of Jack Black, Queen Victoria’s rat catcher, who apart from having a lot of style, used both poison and traps in the mid-1800s.
Rat gestation periods are often only a few weeks long. They can survive on garbage. They reach sexual maturity at only six weeks. Preventing abuse of the bounty purely by biology alone is thus more difficult. It could still be done with shorter intervals for the bounty, for example announcing the first bounty period in advance to be two weeks long, switching to employing people to set poison and traps, waiting a couple months and then running another two week bounty. (Note: some say that the Cobra Effect should actually be called the Rat Effect.)
A Pig Tale
The other example usually connected to the cobra effect is the pig bounty at Fort Benning, Georgia. Of the three animal control examples, this one is the most recent, from 2007 – 2008.
Feral pigs were wreaking havoc on the area surrounding Fort Benning, including destroying equipment and crops. A program was started to pay $40 for each pig tail turned in and hunting restrictions were loosened.
Again, it didn’t work.
“To gauge the effectiveness of the program, we evaluated the population response of wild pigs within 2 study areas on the installation from June 2007 to February 2008. During the study, 1,138 pigs were harvested throughout the installation at a total cost (bounties paid and administration) of US$57,296. Surveys indicated that pig density and occupancy rates increased 23–130% and 12–19%, respectively, during the course of the bounty program. Additionally, sounder size and number of juveniles per adult female increased 144–233% and 191–219%, respectively. These data suggest that the wild pig population was increasing during the period when the bounty program was in effect. We hypothesize that this was due to increased food availability and reproduction associated with baiting wild pigs during the program, and because efforts of program participants were focused on eliminating the segment of the pig population that would maximize return on effort and “trophy” quality of animals rather than on the segment of the population that would most greatly influence population growth.”
(From Effectiveness of a bounty program for reducing wild pig densities). [emphasis mine]
Again, the bounty program was discontinued. Afterward, hunters and trapper were encouraged to go after wild pigs without any bounty.
In this case, even without intentional manipulation of the bounty, pig hunters may have increased the pig population, as stated above, by drawing pigs out with food and therefore supporting more of them in the same habitat. This shows again how important it is to understand how the problem works. While the pigs harvested were sometimes collected in areas that shouldn’t support them (in other words, people were faking the hunting), even if the bounty had lasted, there are other ways it could have eventually failed.
The problem this particular bounty long-term is that transporting pig tails long distances in the US is inexpensive. If the bounty had lasted, I wouldn’t be surprised if tail imports would have accounted for most of the payments.
Turns out you can find bulk pig tails online at pretty affordable prices. You can get 30 pounds (ok, they’re smoked) for only $55. I assume that you could work out a deal to buy them raw with the fur on. Otherwise, if you buy raw pig tails (marketed for dogs), they are a little more expensive at $78 for 30 pounds. So again, you break even on the bounty at just two tails. Note: if you think that no one tried to buy pig tails online for this bounty (and if you think my research into this topic is pushing some limits), you’re not thinking this all the way through. Don’t pause your thinking where you personally would stop pursuing payment. You are probably not the use case.
With gestation periods of 114 days (a little under four months), female maturity at only five months (though they often do not have their first litter until a year old), pigs’ ability to eat scraps, and litters of up to ten piglets, if pigs were smaller, quieter, and could be easily hidden from view, it might just make sense to breed them as well.
How to solve this one? Rather than pay a bounty for tails, or even for whole pigs, employing a few hunters at a rate well above minimum wage at the time (2008) at $120/day (the equivalent of three pig tails at $40) but employing people who identify with the need to eliminate the pigs from the area. That could mean people from farming communities who had no incentive to see the pigs destroy crops. I wonder if the mindset would change over time — in other words if the hunters eventually become corrupted to do the least work possible. I have more uncertainty on how to handle this situation unless the community connection is strong. Once the pigs are collected, offer a butchering service and give the option of either taking the butchered pig themselves or of donating it to the military base or to the poor.
If you find yourself facing a potential cobra effect, redesign it.
(I wrote part two to this post later on.)