An online resource based on the award-winning nature guide

Barn Owl

The Feathered Feet of Northern Owls

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Most owls have feathered legs, but the feet and toes of some owls, especially those living in colder, higher latitudes, are also densely feathered. The feathers keep the feet of these birds warm, allowing them to hunt where snow is on the ground and temperatures are very low. Great Gray Owls (pictured), Snowy Owls and Northern Hawk Owls are all examples of this phenomenon. Owls living in warmer climes, such as Barn Owls, have sparsely feathered feet and toes, and tropical owls have nearly featherless feet. This variation can also be found within a given species that has a range that extends over many degrees of latitude, such as the Barred Owl.

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Owl Night Vision

1-5-15  barn owlIMG_6003Like humans, birds have a sensitive retina in the back of their eyes that absorbs incoming light, senses it, integrates the information in it, and sends this information on to their brain. An avian retina is much thicker than ours and contains more rod cells (for dim light vision) and cone cells (for acuity and color vision).

As most owls are active at night, their eyes must be very efficient at collecting and processing light. The eyes of owls are disproportionately large compared to the size of their skull, and enable them to collect as much light as possible. In addition, the retina of an owl’s eye has an abundance of light-sensitive rod cells — owls have almost a million rods per square millimeter compared to humans which have only about 200,000. Barn owls can see a mouse at 6 – 7 feet with an illumination of .00000073 foot-candles – the equivalent of humans seeing a mouse by the light of a match a mile away. Eye size, an abundance of rod cells and additional neural mechanisms provide owls with vision greater than that of most of their prey.

Since owls have extraordinary night vision, it is often thought that they are blind in strong light. This is not true, because their pupils have a wide range of adjustment, allowing the right amount of light to strike the retina. Some species of owls can actually see better than humans in bright light. (Photo: barn owl, in captivity)

Naturally Curious is supported by donations. If you choose to contribute, you may go to http://www.naturallycuriouswithmaryholland.wordpress.com and click on the yellow “donate” button.