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Snowy Owls

By Ranger Steve Mueller

 

Forty-eight transmitters were attached to Snowy Owls from North Dakota to Maine during 2013-17. The solar powered devices track movements by recording latitude, longitude and altitude. Some owls remain within a quarter mile of where they were tagged and others move hundreds of miles. “Project SNOWstorm” research focuses on winter movements but reveals information gathered on the summer range in the far north that has previously not been accessible.

In winter, some owls spend weeks or months floating on Great Lakes ice where they hunt gulls, ducks, geese, and grebes. Recently, I have observed Snowy Owls on the center dike between massive ponds at the Muskegon Wastewater facility. Thousands of gulls and waterfowl are found in these ponds. I thought the owls depended on lemmings in the far north and ate a similar diet of voles here.

Evidence indicates gulls and waterfowl can be an important part of their diet and is a reason owls perch on floating ice. Capturing a gull provides more food per catch than a small rodent. I wonder what the success rate is for capturing a rodent compared with a bird. It might be more efficient hunting rodents when abundant. 

Massive numbers of gulls are present at the Muskegon wastewater facility. It is a birding hotspot where people scan with scopes to find rarer gulls. My friends, the two Gregs, Jim, and I have seen Greater Black-backed, Glaucous, and other infrequently seen gulls among abundant Ring-billed and Herring Gulls. 

We have only seen the owls observing or moving to new perch locations. They stand patient. It would be nice to see one pursuing a gull. They have 14 neck vertebrae that allows them to turn their head more than half way around. Other birds and mammals have seven cervical vertebrae preventing such great head swivel. Owls can look straight backwards from the direction their body is facing. It appears their head is on backwards. 

Adult males and females can be distinguished by plumage. Males are nearly all white, while female have brown or black flecked feathers. Immatures are more heavily dark marked. Snowy Owls appear larger than they are because fluffy feathers provide a robust appearance. Under the fluff is a lean 3 to 6-pound body. Visible contour feathers covering the body shed water. Underneath, non-waterproof down feathers trap air and insulate. 

Large eyes have a yellow iris with dark penetrating pupils. Like ours, their eyes are on the front of the face providing depth of field binocular vision. Close one eye and notice how the distance of two objects is difficult to discern. When hunting it is important to judge distance while flying. Notice birds at your feeder have eyes on the side of the head. To determine distance, they must move their heads to gain a three-dimensional view. Eyes on the sides of the head provide an advantage of a nearly 360º view for spotting predators.

I did not notice a black transmitter on the back of any owls. It would be just below the skull. With only 48 tagged, I would not expect to see an owl with one. Owls are captured in fine mess nets strung in flight areas. Mist nets are similar to golf course screens installed to prevent balls from entering highways and hitting cars. 

Owls living in the tundra far from human activity reveal their movements when they migrate to our region. Information stored in transmitters north of cell tower range is retrieved when they enter tower range in winter. 

Periodically large numbers move south when arctic food is scarce or populations are high forcing hunting dispersal. This year is an excellent year for learning more about the daily lives of owls for which we know little. Many have already arrived southward. 

Spend time exploring farm country and areas with large fields to search for white bumps. Look with binoculars and you might find a Snowy Owl. Enjoy exploring on your own or participate on Audubon field trips.

Natural history questions or topic suggestions can be directed to Ranger Steve (Mueller) at odybrook@chartermi.net – Ody Brook Nature Sanctuary, 13010 Northland Dr. Cedar Springs, MI 49319 or call 616-696-1753.

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