In the western U.S., Spotted Owls (Strix occidentalis) are one of the banner species for the protection of old growth forests, and several subspecies are federally endangered. A small owl, it has a huge impact on conservation in North America. But now they face a threat that is harder to deal with even than human disturbance and habitat loss. It is a fellow owl, the Barred Owl (Strix varia). The two species are very closely related. The Barred Owl is most commonly found in the eastern portion of the continent, but that is changing.
Due to an increase in the number of planted trees in the central parts of the continent, the breaking up of large tracts of continuous forests by timber harvesting, and probably other factors that we do not yet understand, the Barred Owl has been expanding its range westward. There are now breeding populations of Barred Owls in Washington, Oregon, and California, and this posses a special problem for the Spotted Owl. With their larger size and more aggressive behavior, Barred Owls can drive out Spotted Owls from nesting territories, sometimes eating the Spotted Owls! However, even when the Spotted Owls stand their ground (and don’t end up being a meal) a problem still exists. Since the two species are so closely related, they can interbreed. The hybrid, or Sparred Owl, can then mate with other Sparred Owls or members of their parent species. Since the total Spotted Owl population is small and the total Barred Owl population is large, and getting larger, the overall result is that the Spotted Owl is getting absorbed into the Barred Owl.
Now, we face a dilemma: what should we do to save the Spotted Owl? For that matter, what can we do to save the Spotted Owl? Ideas abound across a wide spectrum. At one end are those that feel that the Spotted Owl must fend for itself. This viewpoint is generally driven by the idea that a species its range is a natural process and should not be interfered with. If one species out competes another where they come in contact, that is just how the world works. Many advocates of this viewpoint point out that if the two species are so closely related that they can interbreed, they probably should not have been categorized as two different species in the first place, but are rather two populations of the same species.
At the other end of the spectrum are those that feel that the Spotted Owl should be protected at almost any cost. Proponents of this viewpoint feel that a large part of what brought these two species together were human induced changes to the land, and we are therefore responsible for the results. Among the most drastic of the plans that have been suggested is to actually kill Barred Owls when they are found near known Spotted Owl nesting territories.
So, who is right? The debate continues. There may be nothing we can do to stop the Spotted Owl from disappearing. But we can learn. Ecosystems are incredibly complex, and we did change the landscape in such a way as to allow this situation to occur. In the future, we need to consider carefully the possible consequences of our actions and perhaps apply the precautionary principle a bit more often.
abirdingnaturalist 
[…] Comments « Spotted Owl vs. Barred Owl […]
Correction: Large tracts of forest are broken up by development, not timber harvesting. For example, Marin county was once a vast forested area that has been replace by McMansions. Let’s not blame timber harvesting for deforestation due to urban sprawl and clearing for agriculture.
Agriculture and development do certainly account for a huge amount of disturbance, but when we are talking about disturbing old growth tracts of forest, timber harvest is the first major source of disturbance.
[…] the Barred Owl. I have written previously about the conflict between Spotted Owl and Barred Owls (https://abirdingnaturalist.wordpress.com/2012/08/17/spotted-owl-vs-barred-owl/). The basic problem is that Barred Owls are expanding their range westward into the range of the […]
[…] between Spotted Owls (Strix occidentalis) and Barred Owls (Strix varia) a couple of times before (here and here). The basic situation is that Barred Owls (generally native to eastern North America) have […]
Same thing is true about the red flicker of the west and yellow flickers of the east- they are merely variations of the same species. Undoubtedly true of the yellow-billed magpie in CA & the regular ones- a probable mutation or sport happened and was then bred into the others around it. Not a separate species at all. We have also seen red squirrels moving into our area, coming farther and farther north each year- as they come they begin to mate with greys at the edge of the overlap of species. Normally if there are very many of both kinds, the 2 kinds bicker a lot, especially over a pecan tree. But right at the overlap area, you see strange mixes- for instance, a scrawny red body with a huge fluffy grey tail, or a grey body with a scrawny red tail. It is just nature, The barred owls are by far the better owls in every way, evolutionarily speaking.
Hi MJ,
Yellow-shafted and Red-shafted Flickers do seem to present a similar evolutionary proximity to one another. However, their situation is very different in that one population is not expanding into and subsuming the other. The Magpies also are not invading one another, and I have not heard of much if any hybridization between the two magpie species in North America. Your squirrel example seems more similar. I am not sure where you live, but in the Western USA, we are definitely seeing more Eastern Fox Squirrels (the red ones) out-competing the native Western Grey Squirrels. I have not seen the hybrids, but at least in some places, the exclusion and displacement of the Grey Squirrels by the Fox Squirrels is pretty dramatic!
I do take some issue with your last comment. The term “better” is definitely a judgement call, and not one that I think can be made about the value or validity of a species. Northern Spotted Owls are a terrifically adapted owl for the environment they evolved in. The fact that they are currently being out-competed by the Barred Owl dos not mean they are worse owls.
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