New Research: California spotted owls and burned forests

Photo of female and juvenile California spotted owl courtesy of University of California Cooperative Extension (

New research has just been published concerning the relationship of burned forests and California spotted owls.  “Dynamics of California Spotted Owl breeding-season site occupancy in burned forests – from researchers D. E. Lee, M.L. Bond and R.B. Siegel – was just published in the latest edition of The Condor, an international journal pertaining to the biology of wild bird species. 

Abstract.  Understanding how habitat disturbances such as forest fire affect local extinction and probability of colonization – the processes that determine site occupancy – is critical for developing forest management appropriate to conserving the California Spotted Owl (Strix occidentalis occidentalis), a subspecies of management concern.  We used 11 years of breeding-season survey data from 41 California Spotted Owl sites burned in six forest fires and 145 sites in unburned areas throughout the Sierra Nevada, California, to compare probabilities of local extinction and  colonization at burned and unburned sites while accounting for annual and site-specific variation in detectability.  We found no significant effects of fire on these probabilities, suggesting that fire, even fire that burns on average 32% of suitable habitat at high severity within a California Spotted Owl site, does not threaten the persistence of the subspecies on the landscape. We used simulations to examine how different allocations of survey effort over 3 years affect estimability and bias of parameters and power to detect differences in colonization and local extinction between groups of sites. Simulations suggest that to determine whether and how habitat disturbance affects California Spotted Owl occupancy within 3 years, managers should strive to annually survey greater than 200 affected and  greater than200 unaffected  historical owl sites throughout the Sierra Nevada 5 times per year. Given the low probability of detection in one year,  we recommend more than one year of surveys be used to determine site occupancy before management that could be detrimental to the Spotted Owl is undertaken in potentially occupied habitat.

11 thoughts on “New Research: California spotted owls and burned forests”

    • Just so we can be clear here, Derek, you’re saying that clearcuting up to 35% of spotted owl habitat has the same exact ecological impact as a high severity wildfire burning 32% of suitable owl habitat….Wow.

  1. It seems the owls misplaced their memo (including the attached memorandum of understanding) regarding the role of owls in “restoration amd stewardship”management activities?

    Wouldn’t it be easier to just do the science first and then “manage” accordingly, rather than figure out a way to derive private profits from publicly-funded management disasters?

      • Spoken like a true believer in this Catch-22. However, I could not disagree more with you, Sharon.

        Science CAN be allowed to set policy objectives but WON’T because the USFS has been a captured agency for a long time. Instead, science gets cherry-picked to support policy objectives.

        The “policy objectives” of this captured agency have been systematically ignoring scientific warnings for decades — resulting in large-scale mismanagement — and deliberately imposing these unnatural disasters on public lands and the nearby rural communities.

        The “policy objectives” are still being carried out by line officers repeatedly caught breaking environmental laws, yet with ZERO personal or professional accountability. Conversely, agency staff whistleblowers (including countless biologists) are routinely, severely, punished and harassed mercilessly.

        Now, this captured agency promises to collaborate with corporate “partners” who will “restore” and practice stewardship?

        Sorry Sharon, but this history demonstrates a well-founded crisis of (and deliberate abuse of) the public trust. This “New Century” in forest planning is simply collaborating in putting the “con” into conservation.

  2. It is WAY more complicated than it seems, as northern goshawks also compete for the same nesting habitats, AND the actual nests, themselves. Generally, since goshawks eat spotted owls, owls either get a nest, or they don’t multiply that year. Since owl core habitats and some nest trees are known, when they burn, they generally burn at higher intensities than managed forests.

    Interestingly enough, we are currently working on thinning foraging habitats, by cutting only ladder fuels (and enhancing oaks), only reducing canopy closure by 5% or less. Specifically, we are cutting suppressed and some intermediate trees, to not only make those stands more fire resistant but, also actually enhancing the stands to favor owls and goshawks foraging areas.

    Pretending that fire behaviors are benign for owls and goshawks. The trends are for bigger, more intense and destructive wildfires, here in California. Wildlife Biologists, who know there fields, are signing off on plans to do more of these kinds of projects. Also, I don’t trust their “modeling” actions, assuming birds that were never found. Models are difficult to prove right or wrong, and we shouldn’t be basing important decisions on models.

  3. I am a pretty simplistic biologist. If their trees burn up, do they go somewhere else or do they hang around? Or do they forage but not nest? These accumulations of data don’t show the mechanisms, and lots of time it is understanding what the creature does that helps us design projects.

    If I wanted to know more about this, I would bring in field wildlife biologists from across the Sierra and ask them what they had observed, and actually I would design research on things they disagreed about or wanted to understand more about..

    • Did the study consider the nearly inevitable re-burn of fire-impacted CASPO habitats that remain unsalvaged? We continuously learn the locations of more and more actual nests, and that allows us to more keenly protect these increasingly rare locations. Poorly located nests fail when other predators can see them. That is where canopy closure is essential to successful breeding. (Yes, I have done both CASPO and goshawk surveys)

      • What?! “nearly inevitable re-burn of fire-impacted CASPO habitats that remain unsalvaged” That’s just nonsense? Is there any scientific evidence to support this assertion? In reality (1) reburn affects a small subset of burned areas, and (2) salvage does not significantly change the probability of reburn. There is fuel whether salvage occurs or not (but the simplified forest structure post-salvage is much less favorable for owls).

        • Re-burns are a MAJOR concern, here in California. The A-Rock Fire burned through parts of the Stanislaus NF, as well as Yosemite National Park, in 1989. The Meadow Fire raged through the unsalvaged part within the park in 2007, severely-impacting what was once majestic old growth. There are now vast areas where 400 year old pines used to live, and can now only support brush, without a seed source.

          That part of the Sierra Nevada has had up to 13 different wildfires in the last 100 years. Fires are, indeed, inevitable here, and disregarding the unavoidable lightning strikes and human-caused wildfires will result in bigger and more destructive wildfires, where even the most fire resistant of trees cannot survive.

          Salvage logging offers better protections from catastrophic re-burns, by reducing both heavy large diameters fuels and small diameter flashy fuels. The Meadow Fire re-burn in Yosemite cost taxpayers 17 million dollars, as well as a huge loss to the tourist industry during one of the biggest weekends in Yosemite National Park. Roads and campgrounds were closed, and health alerts were called as far away as Reno/Tahoe. The daily smoke for 3 weeks made me sick, as well.

          On the Stanislaus National Forest, we salvaged the 1989 A-Rock Fire areas bordering the Park. The 2007 Meadow Fire barely burned through any of the Stanislaus NF, and the difference salvage logging makes is quite striking.

          I can confidently say that owls will be back on the salvaged lands decades long before nest trees can grow within the ravaged Foresta area, where owls were once plentiful, just 30 years ago. It may take as long as 100 years before owls will nest there again.

        • Tree: Your post is interesting for being presented so confidently and matter of fact, despite being completely erroneous in its pronouncements.

          1) In factual (“real”) reality, reburns often greatly increase initial wildfire boundaries, Tillamook Burn, B&B Complex, Biscuit Fire, etc.;

          2) Salvage can significantly reduce the probability and severity of reburns (of course), Tillamook, Burn, B&B Complex, etc., etc.

          I guess that it is true that if one delivers misleading or fabricated information with a sense of self assurance and condescension, others may be more willing to accept such pronouncements as fact.

          The problem is when writing is used. Bald-faced assertions are then subjected to greater consideration and the charade eventually evaporates.

          Thanks, too, for your insights on the favorability of “simplified forest structure post salvage” for owls. You sound pretty confident with that pronouncement, too. Exactly why I don’t trust anonymous “experts” that spew their knowledge via phony names.


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