Charismatic animals and their toxic faeces pose one of world’s ‘greatest challenges of invasive species’
Having grown from a herd of 35 在 2012 至 80 今年, the bloat of so-called “cocaine hippos” was already thought to be the largest outside Africa.
But researchers feared that the herd, which started with one male and three female hippos smuggled by Escobar from a US zoo in the 1980s, could grow to 1,500 over the next 20 years if their promiscuous mating habits continue unabated.
然而, the Medellin cartel founder’s unlikely legacy has been a major driver of tourism to his former ranch, the Hacienda Napoles, and outcry from the local population saw a previous culling attempt collapse after just one animal was killed.
But with the help of drugs from Washington, a local environmental agency has begun to sterilise the creatures.
The governmental group Cornare said it has already sterilised 24 of the animals, using the drug GonaCon, a contraceptive developed by the US Department of Agriculture, which donated 55 doses to help the effort.
Eleven hippos had previously been sterilised “in the traditional way”, according to Cornare.
Escobar – a notorious criminal responsible for kidnappings and death on a vast scale, once thought to be one of the world’s richest men – had purchased various breeds of exotic animals to live on his ranch, such as flamingos, giraffes, zebras and kangaroos.
After his death in a shootout 1993, all of the animals were sold to zoos except for the hippopotami, which can weigh up to 4.5 tonnes and were abandoned as they were too large and aggressive to capture, remaining in a pond at Escobar’s ranch before their feral offspring spread to the Magdalena wetlands.
But with toxic urine and faeces that causes algae blooms, the invasive species have wreaked havoc upon the local ecosystem, 根据科学家的说法, polluting one of Colombia’s main waterways and dominating other species, with no predators to rein them in.
“The real problem with hippos is their uncontrollable reproduction. Being such a territorial species, it offers a lot of danger for the fishing population and other people who live in this area,” Cornare official David Echeverri-Lopez, previously told Vice.
因此, scientists argued for their sterilisation in a scientific paper published in January. Its lead author Nataly Castelblanco-Martínez, of the University of Quintana Roo, previously said she believed the hippos pose “one of the greatest challenges of invasive species in the world”.
The ecologist had called for 30 hippos a year to be culled.
But apart from the logistical challenges posed by the hippos’ internal testicles, the animals have also won the support of the local population, with their tourism appeal now offering a livelihood for some residents who give safari tours and sell hippo-related souvenirs.
Despite calling for “urgent” population control of the hippos in their study, 发表在期刊上 Biological Conservation, the researchers noted that “the proposal of a course of action can become controversial when the species has a charismatic value for the society, regardless of its ecological or social impact”.