In 2007, DEFRA deployed feeding stations throughout the Forest of Dean to trial feeding contraceptives to the wild boar population.
The feeding stations consisted of a heavy steel bowl and another heavy steel lid, which sat on top on the bowl, with a lip hanging over the edge. The boar would be able to lift the lid to get to the food (corn) within the bowl, but the lid would be too heavy for our other wildlife to lift.
Motion sensor cameras were nearby to monitor the stations and the boar activity around them.
They worked, and boar were feeding from the stations as planned. However, once the trial was finished the feeding stations were dismantled and that was the last we heard of it.
NOTE: If a boar has eaten contraceptives, the meat cannot be sold for human consumption and as it is impossible to distinguish which boar had eaten from the stations, no boar meat would be fit for human consumption if this means of control was implemented.
The only way would be to mark the boar, with safe paint, while eating and again, this would be impossible.
The easiest and most effective way to implement contraceptive control measures would be to dart wild boar and mark them with safe paint. This will limit the number of fertile animals and will reduce the number of births per-year.