A failed breeding experiment has led to a hybrid creature running riot in the Grand Canyon. The Beefalo is now growing in number rapidly and causing damage to the landscape, threatening the environment and eco-system and trashing ancient monuments of Native Americans. Yet with a hunting ban in the National Park how can they be controlled? Tom Heap goes in search of the legendary creature and the answers.

The iconic bison is on the emblem on the National Parks yet in 1906 its numbers in America were falling so low 'Buffalo Jones' tried a cross-breeding programme with cattle to create the hardy 'beefalo' hybrid. The state eventually took over the herd and kept numbers down through limited hunting. But the beefalo is wise it seems and has learnt it can escape that threat inside the Grand Canyon National Park.

An estimated population of around 600, and growing by up to 50% a year, is causing huge damage to the park. Its herds concentrate the damage in sensitive areas - drinking dry water holes, polluting them, over grazing and leaving bare soil, their success is damaging the landscape and eco-system. Now they're also kicking down ancient monuments of Native American tribes for whom the canyon is a spiritual home. Meanwhile tourists hoping to catch sight of the creatures have found their cars attacked.

So how do you solve a problem like the beefalo? A massive consultation has begun to look at the lethal and non-lethal options and consider if a cull is a viable option despite the sensitivities in the park. Tom Heap goes tracking the beefalo and asks how much damage will be done before a solution is found.

Presented by Tom Heap and produced in Arizona by Anne-Marie Bullock.