When food is scarce.

Our eighth annual bird count highlighted that there had been a shortage of voles this year.

"The vole population collapsed. A build to a significant population and then a collapse is a known natural occurrence, near cyclical, though there is no science on why this happens."

We noted fewer short-eared owls this year, though any creature for which the vole was a tasty meal would struggle to find the next bite. A series of images snapped by Hamish Paterson shows just what a struggle that can be and the competition in the natural world for the next meal.

PHOTOS: (c) Hamish Paterson

A barn owl thought it had found dinner, when a kestrel had the same idea. Perhaps more nimble, or stronger, or with an advantage of surprise, the kestrel made off with the short-tailed vole. The whole drama was over in seconds, leaving the owl with a 'what just happened' look on its face.