The Barn Owl: Beautiful, silent, deadly.

I always said that if I had to do a presentation with only one bird, I could do it easily with an owl, preferably a barn owl. Most audiences are fascinated by their many interesting adaptations. While most of the owls in North America are in the Strix family, barn owls are a member of the Tyto clan. With piercing dark brown eyes and snowy white feathers with varying amounts of auburn shading and sprinkled with “poppy seed” spots, barn owls are nothing less than striking in their beauty. But this beautiful plumage is altogether functional, honed by nature for millions of years to make this gorgeous bird a deadly killer in the night skies. Barn owls hunt in the dead of night, when the darkness is deepest and most of the world is asleep. Ground-dwelling creatures active at this time, notably mice and voles, are the prime diet of the barn owl. Better than any barnyard cat, a barn owl hunting for itself might kill and eat 6 mice per night, while a mother barnie feeding a family of up to six nestlings might dispatch 40 or more in that same period. How they achieve this record is a testament to their adaptations. Barn owls can see very well in extremely reduced light. If you were to paint the		Coloration Barn owl orphans
windows in the Diamondbacks’ home stadium black and turn off all the lights, a barn owl could successfully see a prey species with the light from one candle burning in center field. But as great as its low-light vision is, its hearing is even more phenomenal. Barn owl ears and hearing are probably among the most studied of all bird senses. Over the years, tests ands experiments have been conducted on barn owls to determine how they hunt, and the findings are fascinating. Placed in a room with dried leaves on the floor, a barn owl was allowed to hunt a mouse under conditions of increasing darkness. A kill was made each time, including a test with no measurable light. Infrared film showed that the owl would quickly fly over the moving mouse, hover briefly while it swung its legs up between its head and the mouse, and then drop its talons, unerringly every time, guided only by the sounds of the mouse walking through the leaves. The ears of the barn owl are their secret. First of all, their ears are hidden behind a disc of feathers that ring their face. This “facial disc,” comprised of acoustically transparent bristles, functions as a satellite dish, focusing incoming sound into ears placed one above and one below their eye line. This asymmetry in ear placement allows the owl to differentiate the arrival time of the sound from left to right, and the arrival intensity from top to bottom, forming a mental crosshairs that allow the owl to fly directly to the source with no visual cues at all.
Another totally cool adaptation that allows them to fly to their target without alerting the prey to their approach is silent flight. Their feathers, covering their entire body including their legs and even extending over their beak, are soft and not shiny. In addition, the leading edges of the first few primary feathers on both wings have no interlocking barbules, forming a comb-like structure unique to owl wings. This allows the air to separate in even parcels around the airfoil of the wing smoothly, causing minimal sound as it separates. These are called muffle feathers and allow the owl to fly with almost total stealth as it attacks its prey. In the language of the Dakota Indians, the owl is called the “night bird who hunts with hushed wings.” Barn owls, like other owls, don’t construct a nest, but rather set up housekeeping in a nook or crevasse which provides a dark safe place during the day. In Arizona, not having a lot of typical barns, we find barn owls living in caves or commonly in the tops of untrimmed palm trees. The brown fronds that droop provide a cavity that is dark and quiet, providing the secrecy that barn owls desire. The main dangers they face, besides wind and rain, are tree trimmers who do their work in the springtime, when owls are actively nesting. Barn owls will lay up to six eggs, each spaced up to two days apart. Unlike ducks that begin incubating with the arrival of the last of several eggs, barn owls will incubate each egg as it is laid, so this means that there can be up to two weeks of		Muffle feather close-up Baby Barn Owl
difference in age between the first and the last hatchlings. In a year with plentiful prey, perhaps all six will fledge, while in a poor year, only one or two might survive infancy. I don’t have enough space to get into all the cool things about owls in general, or barn owls in particular, but let me suggest a bibliography for further reading: Owls, John Sparks & Tony Soper, 1995 Butler and Tanner Ltd. The Barn Owl, Mike Read and Jake Allsop, 1994 Sterling Publishing Co. Owls – Their Life and Behavior, Julio de la Torre, 1990 Crown Publishers, Inc.