By Jon Wogen, TBC Board member, “used with permission by the Renville County Register”.
Last week we introduced you to our Minnesota owls. Many are year-around residents; some are here only as they pass through in migration, others come only in search of food during difficult winters.
The last two winters were hard on people and the snow owls in Canada. Many came here looking for mice and voles to sustain them. The lemmings on the Arctic Tundra were in short supply for food.
Owls are very special. They have forward-looking eyes. This gives them what we call “binocular vision”. Both eyes see in a slightly different dimension which aids in depth perception. That is important in prey location and catching. Many predatory species have binocular vision, even the northern pike, a predatory fish.
Humans have used their binocular vision to develop and use tools and this has helped them to become the dominant creature on the earth. The large brain which can reason and logically solve problems, and our opposable thumb helped to achieve this status.
The ears on owls are also special. They are very sensitive to small sounds. The ears are also a bit asymmetrical, which allows the owls to interpret the sounds they hear and to focus on their location. So, a mouse under some leaves may present very little sound, but the owl can locate it like radar. The ears are hidden under the feathers.
The sound of the mouse under the leaves is also amplified and focused by the shape of the face and its feathers. It is sort of like you cupping hour hands behind your ears to hear distant sounds. The cupped hand enlarges the sound-gathering area of the ears so you can hear better.
The “ears” we see sticking up above the heads of several species of owls are really not the ears at all. They are just there for decoration, or possibly to help break up the shape of the head so it is more camouflaged (?).
Owls are not very good at building nests. They use abandoned nests of other birds such as eagles, ospreys, crows and such. A few species of owls are hole-nesters. They will seek out a broken and rotted branch of a tree or a hollow tree with a proper sized hole for them. The large Barred Owl and the small Screech Owls are cavity nesters.
With Barred Owls and Screech Owls seeking a hollow tree cavity for their nests, they present a chance for us to improve their numbers and secure them as residents in our area. We can build nesting boxes for them. The Barred Owls love swampy, cedar filled wooded areas like the valley of the Minnesota River and perhaps the valleys of some of the creeks running south toward the Minnesota River. The Screech Owls love the forested river valley too, but some even nest in towns in hollow branches of trees or the trunk of the tree if it is old. Many Screech Owls nest in farm groves, especially old groves with broken and rotted-out trees.
Many old farm sites have been bulldozed out and are now producing corn and beans. They were once wildlife sanctuaries but now produce crops. Owls have decreased in numbers as farm windbreaks and groves have disappeared.
The small Burrowing Owls which may nest only rarely in Western Minnesota use the burrows of prairie dogs, ground squirrels, badgers, and rabbits. We would guess that Burrowing Owls are few and far between in our State.
With winter settled in for the duration, we now are presented with a chance to spend some quality time in our wood shop or basement. We can build bird nesting boxes which will make our winter pass faster too.
Building a nice nesting box for our cute, but menacing-looking Screech Owl would be a nice contribution to owl conservation. They will live near people so it would be possible that we can entice them into our backyards with a proper nest box. The Screech Owl nest box will attract Kestrels (Sparrow Hawks) also, as the opening is the same for both of them. In fact, I have a friend who has a Wood Duck nesting box in his grove and it gets Screech Owls in it.
Plans for the Screech Owl/Kestrel nest box can be found in the DNR book, “Woodworking for Wildlife”, which you can find at your local library. The book can also be purchased at State Park offices, or at DNR headquarters in some areas.
You can also go on-line to locate nest box plans, most of which are copies of the one in the DNR book. Your library can order a copy from their book depository also, if they don’t have it.
You may find that starlings will try to take over your nest box. It you have it in your backyard, you can put the ladder up once in a while to eliminate the starling’s nest and after a while they will leave it, in disgust.
If I can fit a plan for the Screech Owl nest box into the column next week, I will. In case I can’t fit it in, go to your library and check the book “Woodworking for Wildlife”, or go on-line.
THE WISDOM OF SVEN
Sven quotes George Washington today: “Government is not reason; it is not eloquent; it is force. Like fire, it is a dangerous servant and fearful master”.