Archived 2011-2012 topics: Spotted Owl (Strix occidentalis): downlist to Least Concern?

This discussion was first published on Dec 1 2010 as part of the 2010-2011 Red List update.

Initial deadline for comments: 31 January 2012.

Link to BirdLife species factsheet for Spotted Owl

Spotted Owl Strix occidentalis is currently listed as Near Threatened under criterion C2a(i), on the basis that its population size is estimated at 15,000 mature individuals (Rich et al. 2004) (which approaches the threshold for Vulnerable of fewer than 10,000 mature individuals), and was suspected to be in decline owing to continued habitat fragmentation, degradation and disturbance through clear-felling and selective logging (del Hoyo et al. 1999), as well as competition from and hybridisation with Barred Owls Strix varia (Kelly and Forsman 2004). In contrast, populations in Mexico are suspected to be stable because of habitat tolerance combined with forestry activities that typically modify rather than destroy habitat (Lammertink et al. 1996, J. M. Lammertink in litt. 1998).

Trend analyses using Audubon Christmas Bird Count data gathered since 1965-66 suggested that this species’s population is not declining, and may even be increasing slightly (Butcher and Nivel 2007). By the 2011 Red List update, this species will have been considered to be stable and possibly increasing in the USA for five years, making it eligible for downlisting to Least Concern, as it does not approach the thresholds for Vulnerable under any of the other criteria. Comments are invited on this potential category change, and further information is requested on this species’s likely population size and population trend, and the current severity of threats.

Butcher, G. S. and Nivel, D. K. (2007) Combining Data from the Christmas Bird Count and the Breeding Bird Survey to Determine the Continental Status and Trends of North American Birds. Washington D.C.: National Audubon Society.

del Hoyo, J., Elliott, A. and Sargatal, J. (1999) Handbook of the birds of the world, Vol 5: Barn- owls to Hummingbirds. Barcelona, Spain: Lynx Edicions.

Kelly, S. G. and Forsman, E.D. (2004) Recent records of hybridization between Barred Owls (Strix varia) and Northern Spotted Owls (Strix occidentalis caurina). Auk 121: 806-810.

Lammertink, J. M., Rojas-Tomé, J. A., Casillas-Orona, F. M. and Otto, R. L. (1996) Status and conservation of old-growth forests and endemic birds in the pine-oak zone of the Sierra Madre Occidental, Mexico. Amsterdam: Institute for Systematics and Population Biology.

Rich, T.D., Beardmore, C.J., Berlanga, H., Blancher, P.J., Bradstreet, M.S.W., Butcher, G.S., Demarest, D.W., Dunn, E.H., Hunter, W.C., Inigo-Elias, E.E., Martell, A.M., Panjabi, A.O., Pashley, D.N., Rosenberg, K.V., Rustay, C.M., Wendt, J.S. and Will, T.C. (2004) Partners in flight: North American landbird conservation plan. Ithaca, NY: Cornell Lab of Ornithology.

Related posts:

  1. Archived 2010-2011 topics: Greater Spotted Eagle (Aquila clanga): information requested.
  2. Archived 2010-2011 topics: Blue Chaffinch (Fringilla teydea): downlist to Least Concern?
  3. Archived 2010-2011 topics: Madeira Laurel Pigeon (Columba trocaz): downlist to Least Concern?
  4. Archived 2011-2012 topics: Black-footed Albatross (Phoebastria nigripes): eligible for downlisting?
  5. Archived 2010-2011 topics: Lesser Kestrel (Falco naumanni): downlist to Near Threatened or Least Concern?
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6 Responses to Archived 2011-2012 topics: Spotted Owl (Strix occidentalis): downlist to Least Concern?

  1. Greg Butcher says:

    I do not recommend that the Christmas Bird Count be used as a primary source of population trend information for this species, primarily because it is so rarely encountered on the CBC. Because this is a highly desired species on a CBC, it may be that special efforts are being made to find it, and those efforts may be more successful in recent years due to accumulated knowledge, even if the species is declining.

  2. Tice Supplee says:

    Spotted Owl populations in the southwest portion of the range face increasing habitat fragmentation threats from fire and drought associated with climate change.

    An inventory of spotted owl territories in the Chiricahua Mountains of Arizona (Global Important Bird Area for this species) in 2008 confirmed 10 breeding pairs-no change in breeding pairs from US Forest Service surveys conducted in 1991-92 and 1997.

  3. Susan Haig says:

    Hi–you might add these refs to the literature to consider:

    Funk, W.C., E.D. Forsman, M. Johnson, T.D. Mullins, and S.M. Haig. 2010. Evidence for recent population bottlenecks in northern spotted owls (Strix occidentalis caurina). Conservation Genetics 11:1013-1021.

    Ishak, H.D., J.B. Dumbacher, N.L. Anderson, J.J. Keane, G. Valkiūnas, S.M. Haig, L.A. Tell, and R.N.M. Sehgal. 2008. Blood Parasites in Owls with Conservation Implications for the Spotted Owl (Strix occidentalis). PLoS-One 3(5): e2304. doi: 10.137/journal.pone.0002304.

    Funk, W.C., T.D. Mullins, E.D. Forsman, and S.M. Haig. 2006. Microsatellite markers for distinguishing Spotted Owls (Strix occidentalis), Barred Owls (S. varia), and their hybrids. Molecular Ecology Notes 7: 285-286.

    Haig, S.M., E.D. Forsman, and T.D. Mullins. 2004. Subspecies relationships and genetic structure in the Spotted Owl. Conservation Genetics 5: 683-705.

    Haig, S.M., T.D. Mullins, E.D. Forsman, P. Trail and L. Wennerberg. 2004. Genetic identification of Spotted Owls, Barred Owls, and their hybrids: evolutionary and legal implications. Conservation Biology 18: 1347-1357.

  4. Steve Holmer says:

    The Northern subspecies is in significant decline, 3% per year range-wide and 7% per year in Washington State. Protection for owl habitat is also not certain. While a new Northern Spotted Owl recovery plan calls for additional protection of high quality habitat, there is also a strong push for aggressive thinning in owl habitat, which is expected to cause short-term declines in the species. The potential long-term benefits have not yet been demonstrated. In addition to the threat of increased competition from the Barred Owl, there is also significant habitat loss resulting from harvest on private lands, as well as renewed calls to eliminate owl protections on federal lands to boost logging levels in Oregon. For these reasons we do not believe the Spotted Owl should be downlisted.

  5. Bryan Bird says:

    Populations of the Mexican spotted owl (Strix occidentalis lucida) have not been monitored in any systematic way and demographic information is lacking. There is a draft revised recovery plan available on the USFWS website (http://ecos.fws.gov/speciesProfile/profile/speciesProfile.action?spcode=B074). There are many flaws in the draft including the assumption that wildfire is the greatest, single threat to this species. In fact, the published literature indicates the bird has high nest site fidelity even after fire and in the short term is successfully reproducing in burned nest sites. Long term effects however on reproductive success is unknown after fire. What may be a greater threat but is not acknowledged is extreme manipulation of the species’ habitat, especially canopy cover, for fuel reduction.

    The most recent information on the species overall numbers indicates that the Arizona population is stable but that the New Mexico MSO population is declining at the rate of 6% annually.

    This subspecies needs attention from the scientific community, as government programs are not adequate to track population trends and demographic information.

  6. Andy Symes says:

    Doug Heiken (Oregon Wild) has sent the following information:

    I have several points to make in support of the need for greater conservation of the northern spotted owl:

    Since the Northwest Forest Plan was adopted …
    * 583,500 acres of owl habitat was lost due to “regeneration harvest” on non-federal forest lands from 1994 to 2004. Cite: Raphael, M.G. (2006). Conservation of listed species: the northern spotted owl and marbled murrelet. Chapter 7 in R.W. Haynes, B.T. Bormann, D.C. Lee, and J.R. Martin (technical editors), Northwest Forest Plan—the first 10 Years (1994–2003): synthesis of monitoring and research results. Gen. Tech. Rep. PNW-GTR. USDA Forest Service, Pacific Northwest Research Station, Portland, Oregon. http://www.fs.fed.us/pnw/publications/gtr651/ p 121. and
    * 155,999 acres of suitable owl habitat was “removed” by “management” (i.e. logging) on federal lands from 1994 to 2003 (includes partial harvest). Cite: U.S. Department of the Interior, Fish and Wildlife Service. 2004. Estimated Trends in Suitable Habitat for The Northern Spotted Owl (Strix occidentalis caurina) on Federal Lands from 1994 to 2003. For Use By: Sustainable Ecosystems Institute for the Northern Spotted Owl 5-year Review. USDI Fish and Wildlife Serv.

    New information on the Threatened northern spotted owl indicates that there are significant new uncertainties for the owl that have not been fully considered at the regional or local scale. As recognized by the spotted owl status review, all existing suitable habitat could be critical to the survival of the spotted owl. These new concerns include:

    • Competition and displacement from the barred owl which is dramatically increasing in numbers throughout the range of the spotted owl. The current plan for spotted owls does not account for the effects of barred owls which compete with spotted owls and exclude spotted owls from otherwise suitable habitat. The barred owl is barely mentioned in the 1994 SEIS. The invasion of the barred owl undermines a critical assumption underlying the Northwest Forest Plan – that all suitable owl habitat is available to spotted owls. Tens of thousands of acres old forest owl habitat (which was in short supply before the barred owl arrived) are now occupied and defended by barred owl to the exclusion of spotted owls. The logical response now is to protect and restore more habitat to reach spotted owl population goals; Implications: Based on well-established species/areas relationships the agencies need to protect more suitable habitat is needed to ensure that these two owl species can co-exist, and to decrease the likelihood of competitive exclusion. This is corroborated by FWS’ Final Recovery Plan for the Northern Spotted Owl, which recommends protection of “substantially all of the older and more structurally complex multi-layered conifer forest outside of MOCAs” in westside provinces (as well as on non-federal lands). “These forests are characterized as having large diameter trees, high amounts of canopy cover, and decadence components such as broken-topped live trees, mistletoe, cavities, large snags, and fallen trees.” See Recovery Action 32. This recovery action is intended to reduce competitive pressures between spotted and barred owls, but unfortunately ana analysis hasnot been done to show how much additional habitat needs to be protected to help assure co-existence of the competing owls, and the USFS and BLM have not taken steps to implement this recovery plan rrecommendation.

    • The effects of West Nile Virus which is fatal to the spotted owl; Implications: A larger population may be better able to survive the stochastic pressures of this disease. It may be important to avoid any further “take” of birds or habitat at least until the disease has run its course. Isolated stands of old-growth may also be important because they may be dryer and have fewer mosquito vectors. Geographic isolation might also help protect them from the contagious spread of the disease.

    • Avian malaria that was recently discovered in spotted owls. Ishak HD, Dumbacher JP, Anderson NL, Keane JJ, Valkiūnas G, et al. (2008) Blood Parasites in Owls with Conservation Implications for the Spotted Owl (Strix occidentalis). PLoS ONE 3(5): e2304. doi:10.1371/journal.pone.0002304 http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0002304 Implications: Malaria weakens the owl and likely reduces reproductive success. Providing habitat to support a larger overall population of spotted owls can help mitigate for reduced reproductive success. When owls are facing multiple stresses, the additional stress from avian malaria can be somewhat mitigated by reducing other stresses such as habitat loss from logging.

    • The potential loss of habitat from Sudden Oak Death syndrome; Implications: Loss of habitat to SOD, makes remaining habitat more valuable than previously considered in any programmatic NEPA document.

    • Greater than expected loss of habitat to wildfire over the last several years; Implications: Loss of habitat to fire and the risk of more such losses, makes all remaining habitat more valuable than previously considered in any programmatic NEPA document.

    • The potential effect of climate change in terms of longer fire seasons; larger and more intense fires; increased tree mortality from fire, insects, and drought stress, consequently altered regional vegetation patterns and climate patterns; and maybe most significantly, uncertainty whether suitable habitat can be regrown from altered young stands in an altered climate regime. Climate change also brings uncertainty in terms of the frequency and duration of inclement weather during the owl breeding season. Franklin et al. (2000) observed that spotted owl populations could decline due solely to weather effects. Implications: Uncertainty in the weather creates uncertainty for the owl. This uncertainty can be mitigated by maintaining a larger population which is more resilient to climatic variations. Under a new climate regime, the average age of forests will likely decline, forest establishment will likely become more difficult; we may not be able to regrow new owl habitat in the reserves as assumed in the NW Forest Plan. Existing old forests are relatively resilient to climate change. It is risky to be conducting regen harvest and expect to be able grow new owl habitat in the reserves under an uncertain climate regime. Global climate change also affects local and regional weather. Spotted owl are known to be sensitive to cold and rain during the nesting season. If inclement weather increases during nesting season, spotted owl nesting success will likely be adversely affected. Dense forests provide owls more protection from inclement weather. “Given that natural resource managers cannot control climate variation and barred owls are likely to persist and increase in the range of the northern spotted owl, maintaining sufficient high quality habitat on the landscape remains the most important management strategy for the conservation of this subspecies.” http://www.naturaloregon.org/2010/08/03/osu-climate-change-may-be-hurting-the-spotted-owl-in-oregon/;

    • Fuel reduction objectives conflict with owl habitat objectives. Under the false premises of the Healthy Forest Restoration Act, the USFS and BLM are aggressively logging owl habitat to save it from fire. Scientific support is lacking for fuel reduction logging to benefit species like spotted owls that prefer to live in dense forests – a fuel rich environment. Surface fuels provide habitat for owl prey; ladder fuels provide owl roosting sites; and canopy fuels provide owl nesting habitat; thus, fuel reduction treatments in owl habitat will almost unavoidably degrade or downgrade some existing owl habitat (or put that habitat at greater risk of fire or barred owl invasion). This means that the remaining owl habitat throughout the owls range becomes more important than previously considered in any programmatic NEPA document. For more information, see Heiken, D. 2010. Log it to save it? The search for an ecological rationale for fuel reduction logging in Spotted Owl habitat. Oregon Wild. v 1.0. May 2010. http://dl.dropbox.com/u/47741/Heiken_Log_it_to_Save_it_v.1.0.pdf The authors of the Northwest Forest Plan expected that 80% of the reserves will become late successional habitat after a period of restoration and recovery. However, recent “Science Findings” from PNW Research reveals that in the dry provinces, “requiring landscape treatments to earn a profit negatively impacted both habitat and fire objectives” and fuel reduction objectives are only compatible with owl habitat objectives, if the owl habitat objective is maintained at 40% (half the target of the NWFP). PNW Research Station. 2006. Seeing The Bigger Picture: Landscape Silviculture May Offer Compatible Solutions To Conflicting Objectives. Science Findings. July 2006. http://www.fs.fed.us/pnw/sciencef/scifi85.pdf Implications: The agencies should re-evaluate whether logging in reserves and in owl habitat is compatible with spotted owl conservation; whether the 40% suitable habitat threshold is sufficient to maintain viable populations of owls in the dry provinces, and whether the reserve system should be expanded to ensure that a 40% slice of a bigger pie might better ensure recovery of the owl.

    • There has also been a continuous loss of suitable owl habitat on non-federal lands that should be considered as a cumulative impact on the viability of the species. There have been almost twice as many acres of owl habitat lost due to stand replacing timber harvest on non-federal lands than that caused by fire on all land allocation combined with logging on federal land allocations. According to Raphael et al (2006) 583,500 acres of owl habitat “losses” can be attributed to “regeneration harvest” on non-federal forest lands from 1994 to 2004. Implications: Continued loss of habitat on private lands renders remaining suitable habitat on federal land more valuable than it was in 1994 when there was more owl habitat on all ownerships. See WOPR DEIS page 195.

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