🦅 The common kestrel is one of the only birds of prey known to see ultraviolet light. Voles and mice leave urine trails across fields that glow under UV, so a kestrel hovering 30 feet up can track those trails directly to the animal below. The “invisible walls” framing in this reel refers to the territorial and sensory boundaries kestrels navigate that no human eye can pick up. Footage captured in the UK. (Via @birdsinmyfield) #wildlife #birds #trial