Publications

hematozoa from the spotted owl.	one hundred five spotted owls (strix occidentalis) from seven populations and three subspecies were examined for hematozoa. haemoproteus noctuae, h. syrnii, leucocytozoon ziemanni, trypanosoma avium, atoxoplasma sp. and unidentified microfilariae were recorded. all northern (s. occidentalis caurina), california (s. occidentalis occidentalis) and mexican (s. occidentalis lucida) spotted owls were infected with at least one hematozoan; 79% had multiple infections. twenty-two percent of the owls we ...	1989	2810564
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
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
occupancy estimation and modeling with multiple states and state uncertainty.	the distribution of a species over space is of central interest in ecology, but species occurrence does not provide all of the information needed to characterize either the well-being of a population or the suitability of occupied habitat. recent methodological development has focused on drawing inferences about species occurrence in the face of imperfect detection. here we extend those methods by characterizing occupied locations by some additional state variable (e.g., as producing young or no ...	2007	17601132
sources of variability in spotted owl population growth rate: testing predictions using long-term mark-recapture data.	for long-lived iteroparous vertebrates that annually produce few young, life history theory predicts that reproductive output (r) and juvenile survival should influence temporal variation in population growth rate (lambda) more than adult survival does. we examined this general prediction using 15 years of mark-recapture data from a population of california spotted owls (strix occidentalis occidentalis). we found that survival of individuals > or =1 year old (phi) exhibited much less temporal va ...	2007	17160689
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
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
modeling species occurrence dynamics with multiple states and imperfect detection.	recent extensions of occupancy modeling have focused not only on the distribution of species over space, but also on additional state variables (e.g., reproducing or not, with or without disease organisms, relative abundance categories) that provide extra information about occupied sites. these biologist-driven extensions are characterized by ambiguity in both species presence and correct state classification, caused by imperfect detection. we first show the relationships between independently p ...	2009	19341151
using topography to meet wildlife and fuels treatment objectives in fire-suppressed landscapes.	past forest management practices, fire suppression, and climate change are increasing the need to actively manage california sierra nevada forests for multiple environmental amenities. here we present a relatively low-cost, repeatable method for spatially parsing the landscape to help the u.s. forest service manage for different forest and fuel conditions to meet multiple goals relating to sensitive species, fuels reduction, forest products, water, carbon storage, and ecosystem restoration. usin ...	2010	20872142
relation between occupancy and abundance for a territorial species, the california spotted owl.	land and resource managers often use detection-nondetection surveys to monitor the populations of species that may be affected by factors such as habitat alteration, climate change, and biological invasions. relative to mark-recapture studies, using detection-nondetection surveys is more cost-effective, and recent advances in statistical analyses allow the incorporation of detection probability, covariates, and multiple seasons. we examined the efficacy of using detection-nondetection data (rela ...	2013	23678946
a quantitative evaluation of the conservation umbrella of spotted owl management areas in the sierra nevada.	whether by design or default, single species management often serves as an umbrella for species with similar habitat requirements. in recent decades the focus of national forest management in the sierra nevada of california has shifted towards increasing closed canopy mature forest conditions through the protection of areas occupied by the california spotted owl (strix occidentalis occidentalis). to evaluate the implications of these habitat changes and the potential umbrella resulting from a sy ...	2015	25905920
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