Great Horned Owls

I recently had an inquiry concerning rabbits and great horned owls in someone’s hometown. The person had been observing what they considered to be an overabundance of rabbits and wondered why there weren’t more owls around to keep their numbers in check.
Great horned owls prey on a wide variety of small mammals, birds, and reptiles including rabbits, squirrels, mice, doves, starling, snakes, and the like. No doubt their diet changes in response to the changes in abundance of their prey species. But any owl population change may come slowly and not that obviously to the casual observer.
Like some other species, great horned owls are very territorial. From what I have read, they will defend a territory of somewhere between 1-4 square miles depending upon conditions. So the density of great horned owls in any particular area may not change much over some given period of time even when the population of a prey species seems to change markedly. Then of course, the change in the owl population would lag by a generation time which is basically a year. There is also the question as to visibility of the owls and rabbits. Rabbits may be quite conspicuous to the casual observer, but owls are quite good at remaining hidden, thus there may actually be more owls in a given area than what our observations would indicate.
If you have some great horned owls in your vicinity they should be more active and conspicuous over the next few months. Across much of North America the courtship season for great horned owls runs from October to December with nesting commencing soon afterward. Robert Stewart in his “Breeding Birds of North Dakota” notes that the breeding season for great horned owls here in North Dakota starts around February.
So it won’t be long before we may be hearing more hooting of the great horned owls as they approach their breeding season. If all goes well, females will lay between 1-4 eggs and incubate them for about thirty days. So if the egg laying period begins in late February the young will begin to hatch around late March.
Although we may not see many great horned owls, owl pellets on the ground are a sure indication that an owl is living nearby. Owls swallow small prey such as mice whole. Larger prey of course must be ripped into smaller pieces. But either way, the owl will eventually regurgitate a pellet of indigestible material such as bone, feathers, or fur. These owl pellets are often found on the ground below a favored perch. Analysis of these owl pellets helps biologists better understand the diet of owls.
Chuck Lura
Natural North Dakota is supported by NDSU Central Grasslands Research Extension Center and Minot State University-Bottineau, and by the members of Prairie Public. Thanks to Sunny 101.9 in Bottineau for their recording services.

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