OWLS: Life in the Cold

March 7, 2019

It’s been a heck of late winter in Montana! Beautiful, but cold - it’s been below zero for days at our field station with lots and lots of snow.

 

While some might be grumbling about the frigid air and persistent shoveling, we’ve also gotten some questions about how this weather affects owls. The answer? Well, that depends on the species.

 

In general, owls are more impacted by the deep snow than the cold; and larger owls are more resilient than smaller owls. For example, Snowy Owls wintering in Montana are well-adapted to the cold and can maintain normal body function down to -40° F.  They are also very capable predators. Although they show a preference for small rodents, they will eat a variety of prey, including larger birds and mammals when deep snow makes hunting small mammals more difficult. 

 

The same is true of Great Horned and Great Gray Owls.  Their large size and insulative, downy feathers combat the cold, and both are known to be able to detect and capture prey through the snow.  However, even the most resilient of species can be affected.  Indeed, we’ve recently received several reports of dead owls. Some of these have been found without obvious injury, while others have been hit by cars. The deep snow may be driving the owls to ‘road-hunt’ where the snow is not so deep.

  

The small to medium-sized owls, however, are likely the most impacted. Long-eared and Northern Saw-whet owls have been seen hunting during the day near houses, perhaps an indication that they are hungry and are desperately trying to make a meal out of small birds or mammals attracted to bird feeders.  Short-eared Owls, Barn Owls, Long-eared Owls, and Northern Saw-whet Owls are all probably having a hard time of it.

 

But who do you suppose is doing just fine? Rodents! Beneath the protection and insulation of snow – in what’s known as the subnivean zone – food supplies are right underfoot, the air remains a consistently warmer temperature, and the snow affords a barrier of protection against predators like owls.

 

So while some owls, sadly, will not survive the winter, our hope is that rodent populations are strong this spring and afford a productive breeding season.

 

© Thomas Bauer, Long-eared Owl, Montana

 

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