The Common Kestrel, our most common bird of prey, are seen regularly by most people hovering alongside our motorways in search of their favourite foods, Bank Voles, Shrews and Mice but they will also take almost anything from beetles and worms to a Dragonfly. But a Kestrels hunting technique would seem a hit and miss affair to many people who think Kestrels just hang there in the air waiting for an unlucky Bank Vole to amble along right underneath for the Kestrel to pounce upon. The truth is much more interesting.
Most small mammals like to use familiar hidden trails and tracks through the undergrowth and long grass; they are also incontinent leaving constant urine trails along these paths. As everyone knows a hawks eyesight is very impressive, but Kestrels have an added bonus, their eyesight is more attuned to the ultra violet end of the colour spectrum, and urine shows up bright yellow under ultra violet light, so those hidden trails now stand out as bright yellow paths through the vegetation to our Kestrel. So in effect a Kestrel is not just prospecting for food when you see him hovering, he’s waiting directly over one of the mammal’s favourite hidden tracks just waiting for one to pass underneath.
In answer to a question over a viewers sighting of a bird of prey hovering on Springwatch a couple of years ago Bill Oddie replied that “If its hovering it’s a Kestrel” This answer could be misleading as I personally have seen Sparrowhawks and Buzzards hovering, although the Sparrowhawk doesn’t hover for as long and the Buzzard is a much larger bird, Bill’s answer was not quite as cut and dried as it may seem.
