The drug kingpin brought four hippos to his estate in the 1980s. Officials estimate that about 170 now roam Colombia, and say the population must be controlled to protect the country’s ecosystem.

When the Colombian drug lord Pablo Escobar was killed in 1993, most of the animals he had imported as pets — zebras, giraffes, kangaroos and rhinoceroses — died or were transferred to zoos.

But not his four hippopotamuses. They thrived. Perhaps a little too well.

Officials estimate that about 170 hippos, descended from Mr. Escobar’s original herd, now roam Colombia, and the population could grow to 1,000 by 2035, posing a serious threat to the country’s ecosystem.