Rim Fire, logging and spotted owls

Here is some timely recent research on what happens to spotted owls after a fire, in particular the Rim Fire which comes up often on this blog (thank you, Larry).  That discussion has often dealt with the effects of post-fire salvage logging, such as the discussion here.  This research discusses the effect of the condition of the forest before the fire on its value to owls after the fire.

This is important because of the argument by some that fires are bigger threat to the owls than cutting down trees to reduce fire risk.  I’ve only looked at this overview and the linked abstract, but it seemed like enough to generate some discussion.  In particular, it contrasts the pre-fire management of Yosemite National Park and the adjacent Stanislaus National Forest.

From the abstract:

Spotted owls persisted and nested within the fire perimeter throughout the four post-fire years of our study at rates similar to what we observed in areas of Yosemite that were unaffected by the fire…  Prior to the fire, spotted owls selected for areas of high canopy cover relative to the rest of the landscape; after the fire, even though territory centers shifted substantially from pre-fire locations, pre-fire canopy cover remained a stronger predictor of spotted owl presence than post-fire canopy cover, or any other pre- or post-fire habitat variables we assessed.

So removing canopy cover, which seems to be one of the goals of fuel reduction, would not benefit the owls even if it reduces fire risk, and it would adversely affect them whether there is a fire or not.

From the lead author:

California Spotted Owls can tolerate forest fire, but Schofield cautions that not all fires are created equal. Yosemite’s forests have not been commercially logged since the early 1900s and fire suppression efforts since the 1970s have been kept to a minimum. This results in a forest structure and fire regime that is distinct from what is found outside of the park.

“In Yosemite there is a diversity of forest habitat” explains Schofield, “This means the Rim Fire burned with a diversity of severities creating a range of post-fire habitat for owls to choose from.” The study notes that in portions of the adjacent Stanislaus National Forest that were also burned by the Rim Fire, burn severity was more homogenous likely due to the contrasting logging and fire management regime on the National Forest.

 

 

12 thoughts on “Rim Fire, logging and spotted owls”

  1. Jon, maybe I’m missing something, but if I read
    “Prior to the fire, spotted owls selected for areas of high canopy cover relative to the rest of the landscape; after the fire, even though territory centers shifted substantially from pre-fire locations, pre-fire canopy cover remained a stronger predictor of spotted owl presence than post-fire canopy cover, or any other pre- or post-fire habitat variables we assessed.”

    Then it sounds like the owls will stick around where there used to be canopy, regardless of whether there is any now?

    If it’s OK for fire to remove canopy cover, it should be OK for fuel treatments to thin canopy cover. What am I missing?

    Reply
    • The mere “presence” of owls, anywhere, really doesn’t mean much. It’s more about their networks of (still) existing nests. Realistically, I think we’d have better success at building new nests for them, in appropriate habitats. If we were to select a tree to build a safe nest, we just might be able to expand their nesting success. With a lack of quality available old growth nesting habitats, shouldn’t we be improving their chances in other ways?

      BTW, we were finding 2 acre patches within thinning units where we could have an island of un-thinned forest. Usually these spots were mostly large (and untouchable) trees, anyway. It’s yet another difference between how lumber companies and the Forest Service do “commercial logging” differently.

      Reply
      • You’ve piqued my curiosity about artificial nests. There’s seems to have not been much written about the idea, so I have to think that nests are not really a limiting factor (as opposed to nesting habitat). I did find this from 1992:

        “Artificial nest sites probably could be considered for these owls in large trees Woodbridge and Mattison pers. comm.). European owls in the genus Strix readily use nest boxes (Southern 1970, Saurola 1989). Barred owls also use nest boxes (Johnson 1987). If spotted owls behave in a similar fashion to other Strix owls, providing nest boxes may solve problems with availability of nest sites in some areas. However, a critical study of nest-box acceptance by spotted owls has not been conducted. “https://www.fws.gov/pacific/ecoservices/endangered/recovery/NSO/NSOVolumeI.pdf

        Reply
        • NSOs generally do not use artificial nests. Great gray owls, on the other hand, are super lazy strix and use nest platforms and boxes all the time if they are available.

          Reply
        • I didn’t really mean boxes. Imagine a crew of wildlife folks working in a stand of trees that could be a new owl PAC, but lacks actual nests. They would line out, like a timber crew, and march across the area, looking for candidate nest trees. We know they need canopy cover, and they like hollows and forks. They are also notoriously lazy in building new nests. Another benefit to building them is that we will know where they are, and they can be monitored. While it seems like it might be some kind of crazy plan with little expected impact, the longer term benefits could be much better. The costs would be pretty minimal but, I wonder how quickly a pair of owls would adopt a new nest system. Maybe four nests per PAC?

          It would also, possibly, help out goshawk populations, too. They use the same nesting habitats.

          Reply
    • I agree that seems a little inconsistent, but it could be that owls know what to do when the forest burns, but logging not so much. Regardless, I think it weakens the idea that thinning to prevent fires can be justified as being beneficial to spotted owls.

      Reply
      • Jon, it’s not “thinning to prevent fires”.. it’s thinning to make fires more manageable (that doesn’t work in all conditions, but does work in many).

        Now it used to be true that spotted owls liked big trees and old growth multilayered habitat. But that can become all crispy and dead, as in the film Wilder Than Wild.

        Logically, if they are fine with crispy and dead (and with time, fallen, crispy and dead) then they never needed “traditional old growth habitat” in the first place.

        Reply
        • You’re using human logic; not owl logic. But my take was that owls are only fine with crispy and dead if there is enough heterogeneity to find some alive nearby that meets their needs for nesting habitat.

          Reply
  2. A quick look at aerial photos shows a lot more old growth mortality inside of Yosemite, than in the National Forest. (Of course, much of the Rim Fire was a recent re-burn, outside of the Park) I also visited the area of Hogdon Meadow and saw all these dead and dying old growth trees. Since wildfires are very common here, it is assured that these snags will burn in the next 20-40 years. Of course, that doesn’t factor in the human-caused fires, either.

    Reply

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