Sunflower seeds treated to help slow breeding

A team of US scientists are treating seeds with a form of birth control in order to help slow down the increasing number of grey squirrels in the wild.

Unfortunately, some areas are struggling to cope with the species' tendencies to devour famers' crops, chewing into building wires and damaging - if not, killing - trees by stripping bark.

Following a warm winter that has caused an increase in nuts, in certain areas of the USA there has been a rise in the number of grey squirrels. In an attempt to slow breeding, scientists at South Carolina's Clemson University are coating the squirrels' favourite seeds with birth control.

The scientists have spent the past year studying the squirrels and taking blood samples from some in order to understand their hormone levels. A cholesterol-lowering drug, which affects the molecule in which sex hormones are made, has been effective in lab squirrels.

Sixteen of the campus's grey squirrel feeders now offer black sunflower seeds covered with the drug, and will continue to do so for another year while gathering information to assess how well the treatment is working.

"The squirrels don't seem to mind," said graduate student and project leader Kristina Dunn. "I've seen them sitting there just eating, eating, eating."