Miami Is Thinking Of Offering Bounties For Dead Iguanas. It Desperately Needs To Google The "Cobra Effect"

We politely suggest that Miami commissioners might want to look up the "Cobra Effect" before taking action.

James Felton

James Felton

Senior Staff Writer

clockSep 21 2022, 14:19 UTC
A green iguana rests, majestically and invasively, on a log.
The commissioner wants them dead or alive. Image credit: abdul hafiz ab hamid/

Miami Beach is considering paying bounties for dead iguanas, after the cost of paying professionals to destroy the creatures rocketed to over $200,000. 

Miami Beach has an iguana problem. An invasive species of American iguana (aka green iguana) is flourishing in the area, and causing all kinds of destruction. The species, native from southern Brazil all the way up to Mexico, was first reported in Florida in the 1960s. As well as damaging vegetation (eating just about any vegetable or fruit they can get their mouths on), a native species of tree snails has been found in their stomachs, suggesting they could be a threat to the endangered species.


At the moment, the species is protected by anti-cruelty laws but can be legally "humanely" killed by residents in Florida. However, Miami Beach Commissioner Kristen Rosen Gonzalez suggested in a meeting last week that the problems of rising exterminator costs and the iguana problem itself could be solved by offering bounties for the animal.

“I don’t know – dead or alive. But if we pay per iguana we’re going to get more iguanas,” Gonzalez said in the meeting, according to a report from Local 10. “People are going to go out and hunt them for money. I think that’s a better use of our money.”

As neat (and likely inhumane) as that sounds as a solution, history is full of examples of similar schemes where the organizers soon learned they'd been inadvertently incentivizing the wrong behavior. The most famous example is ironically, given the comparative lack of evidence compared to other similar tales that of the "Cobra Effect".

The story goes like this: during direct rule by Britain in India, the British Colonial Government decided to attempt to control the cobra population in Delhi. Like Miami 2022, they thought that it would be a good idea to offer a bounty for any dead cobras handed into the administration. At first, it seemed successful, given that dead cobras kept showing up in huge numbers. Then it seemed unsuccessful, given that dead cobras kept showing up in huge numbers.


The government, in its thirst for dead cobras, had not considered that they were actually incentivizing people to breed cobras themselves and then kill them, in order to collect the bounty. 

A similar scenario played out in Hanoi, Vietnam, in 1902 when the city became overwhelmed by rats. The colonial French administration began paying members of the public to kill the rats, or so they thought. Deciding that it would be too much of an effort to deal in rat corpses, the colonial rulers decided that they would pay 1 cent per rat tail. 

At first, the scheme looked like a massive success. Rat tails were flooding in, and it appeared people were slaughtering the rodents in impressive numbers.

Soon though, officials venturing into the Vietnamese part of the city took a closer look at some of the rats running around and noticed a distinct lack of tail where the tail should be. Rather than killing the rats, entrepreneurial types had merely cut off their tails and released them into the wild to breed more valuable tails. 


Essentially, in an attempt to incentivize rat-killing, the government had accidentally incentivized rat maiming. Worse, people started farming the rats themselves in order to make money. The rat population exploded, and a year later the city began to see cases of bubonic plague, followed by a larger outbreak in 1906. 

So, Miami, before you take this idea any further, we beg of you to look at these examples and reconsider. 

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  • invasive species