| helminth parasites of northern spotted owls (strix occidentalis caurina) from oregon. | helminth parasites are reported for the first time from northern spotted owls. seventy-one percent of a sample of strix occidentalis caurina from western oregon was infected. nematodes (porrocaecum depressum, capillaria falconis, microtetrameres sp. and synhimantus hamatus) were the most prevalent parasites although cestodes (paruterina rauschi) and acanthocephalans (centrorhynchus conspectus) were also represented. there was an association between components of this helminth fauna and the diet ... | 1989 | 2716105 |
| enteric coccidia (apicomplexa) in the small intestine of the northern spotted owl (strix occidentalis caurina). | sporulated oocysts (mean dimensions = 13.0 x 10.8 microns) and sporocysts (11.3 x 5.5 microns) of a coccidian resembling frenkelia sp. or sarcocystis sp. were present in the lamina propria of the small intestine of a naturally-infected northern spotted owl (strix occidentalis caurina) collected near medford, oregon (usa). dimensions of these oocytes and sporocysts appear to be considerably smaller than those from other sarcocystid species with avian definitive hosts. additionally, numerous devel ... | 1993 | 8355357 |
| infestation of northern spotted owls by hippoboscid (diptera) flies in northwestern california. | hippoboscid flies were found on 62 (17%) of 382 northern spotted owls (strix occidentalis caurina) captured between april and september, 1986 through 1990. two species of hippoboscids were identified: icosta americana and ornithomya anchineuria. male and female adult spotted owls had similar prevalences and relative densities of hippoboscid flies. juvenile owls had lower prevalence and relative densities than adults. there were no significant differences in mean intensity of hippoboscids on adul ... | 1993 | 8487378 |
| why ecosystem management can't work without social science: an example from the california northern spotted owl controversy | it is increasingly obvious that social science, while not a sufficient condition for making ecosystem management effective, is a necessary condition. a social science typology of ecosystems is developed, applied, and shown to have substantial and unexpected implications for the practice of ecosystem management. ecologists and environmental scientists, in particular, will find some conclusions uncomfortable. the application involves a case material from the california northern spotted owl controv ... | 1996 | 8703104 |
| a generalized fecal glucocorticoid assay for use in a diverse array of nondomestic mammalian and avian species. | noninvasive fecal glucocorticoid analysis has tremendous potential as a means of assessing stress associated with environmental disturbance in wildlife. however, interspecific variation in excreted glucocorticoid metabolites requires careful selection of the antibody used in their quantification. we compared four antibodies for detecting the major fecal cortisol metabolites in yellow baboons following (3)h cortisol administration, acth challenge, and hplc separation of fecal glucocorticoid metab ... | 2000 | 11121291 |
| times to extinction for small populations of large birds. | a major practical problem in conservation biology is to predict the survival times-"lifetimes"-for small populations under alternative proposed management regimes. examples in the united states include the 'alala (hawaiian crow; corvus hawaiiensis) and northern spotted owl (strix occidentalis caurina). to guide such decisions, we analyze counts of all crow, owl, and hawk species in the most complete available data set: counts of bird breeding pairs on 14 european islands censused for 29-66 conse ... | 1993 | 11607439 |
| fatal spirochetosis due to a relapsing fever-like borrelia sp. in a northern spotted owl. | acute septicemic spirochetosis was diagnosed in an adult male northern spotted owl (strix occidentalis caurina) found dead in kittitas county, washington, usa. gross necropsy findings included marked enlargement of the liver and spleen and serofibrinous deposits on the serous membranes lining the body cavities and the pericardial and perihepatic sacs. microscopic observations included macrophage infiltration in the liver and spleen with mild thrombosis and multifocal necrosis, as well as hemorrh ... | 2002 | 11838214 |
| genetic structure, introgression, and a narrow hybrid zone between northern and california spotted owls (strix occidentalis). | the northern spotted owl (strix occidentalis caurina) is a threatened subspecies and the california spotted owl (strix occidentalis occidentalis) is a subspecies of special concern in the western united states. concern for their continued viability has arisen because of habitat loss caused by timber harvesting. the taxonomic status of the northern subspecies has been the subject of continuing controversy. we investigated the phylogeographical and population genetic structure of northern and cali ... | 2005 | 15773939 |
| noninvasive measures of reproductive function and disturbance in the barred owl, great horned owl, and northern spotted owl. | there is an urgent need for noninvasive methods to study reproduction and environmental stress in at-risk species such as the northern spotted owl (strix occidentalis caurina). two related owl species (barred owl and great horned owl) were used as surrogates to validate hormone assays for fecal metabolites of progesterone, 17beta-estradiol, testosterone, and corticosterone. infusions of radiolabeled hormones showed that the owls excreted most hormone within 6 h. feces and urine contained roughly ... | 2005 | 16055847 |
| the northwest forest plan: origins, components, implementation experience, and suggestions for change. | in the 1990s the federal forests in the pacific northwest underwent the largest shift in management focus since their creation, from providing a sustained yield of timber to conserving biodiversity, with an emphasis on endangered species. triggered by a legal challenge to the federal protection strategy for the northern spotted owl (strix occidentalis caurina), this shift was facilitated by a sequence of science assessments that culminated in the development of the northwest forest plan. the pla ... | 2006 | 16903089 |
| conservation of the northern spotted owl under the northwest forest plan. | development of the northwest forest plan (nwfp) was motivated by concerns about the over-harvest of late-seral forests and the effects of intensive forest management on the long-term viability of the northern spotted owl (strix occidentalis caurina). following several years of intense political and legal debates, the final nwfp was approved in 1994. even though the plan evolved with a broad ecosystem perspective, it remained anchored in the spotted owl reserve design proposed in 1990. based on a ... | 2006 | 16903090 |
| conserving old-growth forest diversity in disturbance-prone landscapes. | a decade after its creation, the northwest forest plan is contributing to the conservation of old-growth forests on federal land. however the success and outlook for the plan are questionable in the dry provinces, where losses of old growth to wildfire have been relatively high and risks of further loss remain. we summarize the state of knowledge of old-growth forests in the plan area, identify challenges to conserve them, and suggest some conservation approaches that might better meet the goals ... | 2006 | 16903096 |
| the importance of being spatial (and reserved): assessing northern spotted owl habitat relationships with hierarchical bayesian models. | regional conservation planning increasingly draws on habitat suitability models to support decisions regarding land allocation and management. nevertheless, statistical techniques commonly used for developing such models may give misleading results because they fail to account for 3 factors common in data sets of species distribution: spatial autocorrelation, the large number of sites where the species is absent (zero inflation), and uneven survey effort. we used spatial autoregressive models fi ... | 2008 | 18477026 |
| blood parasites in owls with conservation implications for the spotted owl (strix occidentalis). | the three subspecies of spotted owl (northern, strix occidentalis caurina; california, s. o. occidentalis; and mexican, s. o. lucida) are all threatened by habitat loss and range expansion of the barred owl (s. varia). an unaddressed threat is whether barred owls could be a source of novel strains of disease such as avian malaria (plasmodium spp.) or other blood parasites potentially harmful for spotted owls. although barred owls commonly harbor plasmodium infections, these parasites have not be ... | 2008 | 18509541 |
| overestimation of fire risk in the northern spotted owl recovery plan. | the u.s. fish and wildlife service's recent recovery plan for one of the most carefully watched threatened species worldwide, the northern spotted owl (strix occidentalis caurina), recommended a major departure in conservation strategies in the northwestern united states. due to concern about fire, the plan would switch from a reserve to a no-reserve strategy in up to 52% of the owl's range. fuel treatments (e.g., thinning) at regular intervals also would occur on up to 65-70% of dry forests in ... | 2009 | 19549218 |
| underestimating risks to the northern spotted owl in fire-prone forests: response to hanson et al. | | 2010 | 20121850 |
| non-invasive measurement of thyroid hormone in feces of a diverse array of avian and mammalian species. | we developed and validated a non-invasive thyroid hormone measure in feces of a diverse array of birds and mammals. an i(131) radiolabel ingestion study in domestic dogs coupled with high pressure liquid chromatography (hplc) analysis, showed that peak excretion in feces occurred at 24-48h post-ingestion, with i(131)-labelled thyroid hormone metabolites excreted primarily as triiodothyronine (t3) and relatively little thyroxine (t4), at all excretion times examined. the immunoreactive t3 profile ... | 2010 | 20412809 |
| identifying shared genetic structure patterns among pacific northwest forest taxa: insights from use of visualization tools and computer simulations. | identifying causal relationships in phylogeographic and landscape genetic investigations is notoriously difficult, but can be facilitated by use of multispecies comparisons. | 2010 | 21060824 |
| spotted owls and old growth logging in the pacific northwest. | northern spotted owls, strix occidentalis caurina, require large tracts of old-growth conifer forest to survive and reproduce. much of this forest has been or is being cut by commercial logging operations, with uncertain consequences for the owls. in this paper i present simulation models of owl population change over the next 100 years, as summing a variety of scenarios for habitat destruction and fragmentation. my analysis differs from previous models by incorporating patchy territory distribu ... | 1989 | 21129025 |
| Transient dynamics of invasive competition: barred owls, spotted owls, habitat, and the demons of competition present. | The recent range expansion of Barred Owls (Strix varia) into the Pacific Northwest, where the species now co-occurs with the endemic Northern Spotted Owl (Strix occidentalis caurina), resulted in a unique opportunity to investigate potential competition between two congeneric, previously allopatric species. The primary criticism of early competition research was the use of current species' distribution patterns to infer past processes; however, the recent expansion of the Barred Owl and the abil ... | 2011 | 22073635 |
| avian trichomonosis in spotted owls (strix occidentalis): indication of opportunistic spillover from prey. | avian trichomonosis, caused by the flagellated protozoan parasite trichomonas gallinae, has variable pathogenicity among bird species ranging from asymptomatic infections to severe disease periodically manifesting in epidemic mortality. traditionally, columbids are identified as highly susceptible to infection with occasional spillover into raptors that prey on infected birds. we identified avian trichomonosis in two dead california spotted owls (strix occidentalis occidentalis) and three dead n ... | 2016 | 27833856 |
| evaluating carbon storage, timber harvest, and habitat possibilities for a western cascades (usa) forest landscape. | forest policymakers and managers have long sought ways to evaluate the capability of forest landscapes to jointly produce timber, habitat, and other ecosystem services in response to forest management. currently, carbon is of particular interest as policies for increasing carbon storage on federal lands are being proposed. however, a challenge in joint production analysis of forest management is adequately representing ecological conditions and processes that influence joint production relations ... | 2016 | 27755743 |
| divergence in sink contributions to population persistence. | population sinks present unique conservation challenges. the loss of individuals in sinks can compromise persistence; but conversely, sinks can improve viability by improving connectivity and facilitating the recolonization of vacant sources. to assess the contribution of sinks to regional population persistence of declining populations, we simulated source-sink dynamics for 3 very different endangered species: black-capped vireos (vireo atricapilla) at fort hood, texas, ord's kangaroo rats (dip ... | 2015 | 26032147 |
| toward an experimental basis for protecting forest wildlife. | social and economic debates over allocation of old-growth forests have spawned conservation strategies that are aimed at protecting sensitive wildlife species while allowing limited timber harvesting. we are interested in improving the scientific underpinnings for such conservation strategies, because doing so might both minimize costs of resource development and provide more reliable protection. here, we discuss potential consequences from inductive inferencing systems used to develop technical ... | 1993 | 27759319 |
| differential impacts of wildfire on the population dynamics of an old-forest species. | ecological disturbances shape and maintain natural communities, but climate change and human land use can alter disturbance regimes and affect population persistence and vital rates in unpredictable ways. species inhabiting landscapes shaped by wildfire have evolved mechanisms allowing them to persist under this dynamic disturbance type, which creates habitats of varying quality for these species. we utilized data from a 26-yr demographic study of northern spotted owls to analyze the influence o ... | 2017 | 28294305 |
| multistate models reveal long-term trends of northern spotted owls in the absence of a novel competitor. | quantifying spatial and temporal variability in population trends is a critical aspect of successful management of imperiled species. we evaluated territory occupancy dynamics of northern spotted owls (strix occidentalis caurina), california, usa, 1990-2014. the study area possessed two unique aspects. first, timber management has occurred for over 100 years, resulting in dramatically different forest successional and structural conditions compared to other areas. second, the barred owl (strix v ... | 2016 | 27065016 |
| barred owls and landscape attributes influence territory occupancy of northern spotted owls. | we used multi-season occupancy analyses to model 2 fates of northern spotted owl territories in relation to habitat amount, habitat fragmentation, and the presence of barred owls in washington state, usa, 1989-2005. local colonization is the probability a territory unoccupied by a spotted owl in year i would be occupied in year i + 1, and local extinction is the probability a territory that was occupied by a spotted owl in year i would be unoccupied in year i + 1. we found a negative relationshi ... | 2014 | 25558093 |
| the roles of competition and habitat in the dynamics of populations and species distributions. | the role of competition in structuring biotic communities at fine spatial scales is well known from detailed process-based studies. our understanding of competition's importance at broader scales is less resolved and mainly based on static species distribution maps. here, we bridge this gap by examining the joint occupancy dynamics of an invading species (barred owl, strix varia) and a resident species (northern spotted owl, strix occidentalis caurina) in a 1000-km study area over a 22-year peri ... | 2014 | 24669721 |
| using detection dogs to conduct simultaneous surveys of northern spotted (strix occidentalis caurina) and barred owls (strix varia). | state and federal actions to conserve northern spotted owl (strix occidentalis caurina) habitat are largely initiated by establishing habitat occupancy. northern spotted owl occupancy is typically assessed by eliciting their response to simulated conspecific vocalizations. however, proximity of barred owls (strix varia)-a significant threat to northern spotted owls-can suppress northern spotted owl responsiveness to vocalization surveys and hence their probability of detection. we developed a su ... | 2012 | 22916175 |
| inadvertent advocacy. | policy advocacy is an issue regularly debated among conservation scientists. these debates have focused on intentional policy advocacy by scientists, but advocacy can also be unintentional. i define inadvertent policy advocacy as the act of unintentionally expressing personal policy preferences or ethical judgments in a way that is nearly indistinguishable from scientific judgments. a scientist may be well intentioned and intellectually honest but still inadvertently engage in policy advocacy. t ... | 2012 | 22280324 |
| eliminating the artificial effect of sample mass on avian fecal hormone metabolite concentration. | avian endocrinology is a productive field that could benefit from increased application of non-invasive techniques. although assay protocols vary, most studies that measure hormone metabolites in avian feces struggle with an artificial effect of sample mass on steroid metabolite concentration. hormone metabolite concentrations measured in small samples are consistently higher than concentrations in larger samples, and this appears to be due to multiple methodological problems. we systematically ... | 2010 | 20709063 |
| evaluating areas of high conservation value in western oregon with a decision-support model. | the northwest forest plan was implemented in 1994 to protect habitat for species associated with old-growth forests, including northern spotted owls (strix occidentailis caurina) in washington, oregon, and northern california (u.s.a.). nevertheless, 10-year monitoring data indicate mixed success in meeting the ecological goals of the plan. we used the ecosystem management decision-support model to evaluate terrestrial and aquatic habitats across the landscape on the basis of ecological objective ... | 2010 | 20184658 |
| introgression and dispersal among spotted owl (strix occidentalis) subspecies. | population genetics plays an increasingly important role in the conservation and management of declining species, particularly for defining taxonomic units. subspecies are recognized by several conservation organizations and countries and receive legal protection under the us endangered species act (esa). two subspecies of spotted owls, northern (strix occidentalis caurina) and mexican (s. o. lucida) spotted owls, are esa-listed as threatened, but the california (s. o. occidentalis) spotted owl ... | 2008 | 25567499 |
| phylogeography of spotted owl (strix occidentalis) populations based on mitochondrial dna sequences: gene flow, genetic structure, and a novel biogeographic pattern. | mitochondrial dna control region sequences of spotted owls (strix occidentalis) allowed us to investigate gene flow, genetic structure, and biogeographic relationships among these forest-dwelling birds of western north america estimates of gene flow based on genetic partitioning and the phylogeography of haplotypes indicate substantial dispersal within three long-recognized subspecies. however, patterns of individual phyletic relationships indicate a historical absence of gene flow among the sub ... | 1999 | 28565647 |
| new forestry principles from ecosystem analysis of pacific northwest forests. | forest management practices on federal lands in the pacific northwest of the united states have been the center of intense controversy. conflicting value systems, new information, and new perspectives have fueled the debate over the balance between timber production and preservation of natural ecosystems. in this paper we consider examples from three aspects of forest management: (1) management of forest stands, (2) management of the patchwork of forest stands at the landscape scale, and (3) man ... | 1992 | 27759258 |
| integrating scientific methods with habitat conservation planning: reserve design for northern spotted owls. | to meet the requirements of congressional legislation mandating the production of a "scientifically credible" conservation strategy for the threatened northern spotted owl (strix occidentalis caurina), the interagency spotted owl scientific committee employed scientific methods to design a habitat reserve system. information on the current and historical distributions of the owl and its habitats was reviewed in light of economic, political, and legal constraints; results were used to develop a p ... | 1992 | 27759197 |
| using search time and regression to estimate abundance of territorial spotted owls. | using conventional sampling methods, unbiased, precise estimates of the number of individuals in a population can be difficult to obtain for rare, secretive species. we used a leslie regression model (arm) to estimate the number (n0 ) and the variance of the number (v[n0 ]) of adult and subadult northern spotted owls in a territorial population from direct counts within a 292 km(2) study area. estimates of n0 from day counts were more accurate and precise and more robust to fluctuations in surve ... | 1991 | 27755657 |
| demographic models of the northern spotted owl (strix occidentalis caurina). | calassical demographic methods applied to life history data on the northern spotted owl yield and estimate of the annual geometric rate of increase for the population of λ=0.96±0.03, which is not significantly different from that for a stable population (λ=1.00). sensitivity analysis indicates that adult annual survivorship has by far the largest influence on λ, followed by the probability that juveniles survive dispersal, and the adult annual fecundity. substantial temporal fluctuations in demo ... | 1988 | 28312437 |