Since the 1980s, wild boar numbers have exploded across the world.

They are carriers of swine flu, and prompted the building of a 42-mile wall between Denmark and Germany in 2019.

In parts of Germany and in Japan, wild boars running around are contaminated with nuclear radiation.

In the US, they're thought to be responsible for more than $1 billion of damage every year.

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Wild boars are thriving across the world.

On July 30, The Guardian published an article called "Boar Wars: how wild hogs are trashing European cities" highlighting the issue.

Since the 1980s, warmer temperatures, more food, and fewer predators have meant their numbers have exploded. In cities in Europe, China, Pakistan, and the US, their presence is becoming more common — and more of a nuisance.

In the US, in 2013 there were thought to be 5 million wild boars running loose, and they're responsible for more than $1 billion of damage every year.

Growing numbers prompted the building of a wall between Denmark and Germany to secure Denmark's billion-dollar pork industry. In Poland, they caused hundreds of thousands to demonstrate after the government was thought to be embarking on a massive cull.

Some wild boar, in parts of Germany near Russia and in Japan, are contaminated with nuclear radiation.

Wild boars got a lot of attention in July with a viral tweet that said: "Legit question for rural Americans - How do I kill the 30-50 feral hogs that run into my yard within 3-5 mins while my small kids play?"

The Washington Post noted that the boars, also known as hogs, are "resilient in the face of helicopter assaults, threats of mass poisoning and elaborate traps."

Here are 22 photos showing how boars are taking over the world.