In the world of bad behavior, you tend to get more of whatever you permit, a point that is not lost in the world of nature, where not everything is "click and treat."
Over at the Wildfowl and Wetlands Trust's Slimbridge Reserve in Gloucestershire, the first pair of wild Common Cranes to nest in western Britain in 400 years have had a few chicks, but the local fox are on the prowl and they nearly succeed in grabbing the four-day old chicks.
So far, the parents are prevailing in their defense, but in the game of life success is never assure for either side.
The National Audubon Society once successfully sued the Humane Society of the United States to make sure that leghold traps could continue to be used in California to catch and remove red fox that predated on nesting endangered bird species. In the UK, however, leghold traps are banned, as is poison, so only terriers, guns, and snares are available for fox management and control. Of those three methods, terrier work is the most humane.