| experimental infection of california birds with western equine encephalomyelitis and st. louis encephalitis viruses. | a total of 27 bird species from the san joaquin and coachella valleys of california were inoculated subcutaneously with sympatric strains of western equine encephalomyelitis (wee) and st. louis encephalitis (sle) viruses. overall, 133 of 164 birds inoculated with wee virus developed a viremia detected by plaque assay; significantly greater than 72 of 163 birds inoculated with sle virus. host competence was calculated as the average number of days that each avian species had a viremia > or = 2 lo ... | 2003 | 14765678 |
| isospora celata n. sp. (apicomplexa: eimeriidae) from the orange-crowned warbler oreothlypis celata (say) (passeriformes: parulidae) in mexico. | a new coccidian species (protista: apicomplexa: eimeriidae) is described from the orange-crowned warbler oreothlypis celata (say) collected in the nevado de toluca national park, mexico at 3,000 metres above sea level. isospora celata n. sp. has subspheroidal oöcysts, measuring 28.4 × 26.4 μm, with smooth, bi-layered wall c.1.2 μm thick. micropyle and polar granule are absent, but oöcyst residuum is present as a compact mass. sporocysts are ovoidal, 18.2 × 12.8 µm. stieda body knob-like and sub- ... | 2014 | 25301514 |
| survey of birds and lizards for ixodid ticks (acari) and spirochetal infection in northern california. | a total of 138 birds (24 species) was captured in an oak woodland between december 1988 and june 1989 at the university of california, sierra foothill range field station, yuba county, calif. ticks were not found on 71 birds captured between december 1988 and march 1989. five subadult ixodes pacificus cooley & kohls were removed from 3 of 67 birds caught between april and june 1989. these three birds, an orange-crowned warbler (vermivora celata (say], a lazuli bunting (passerina amoena (say], an ... | 1990 | 2280384 |
| migratory birds and the dispersal of arboviruses in california. | each spring large numbers of neotropical migrants traversing the pacific flyway pass through the coachella valley enroute to northern destinations, providing an opportunity to test the hypothesis that mosquito-borne encephalitis viruses are introduced annually into california by migratory birds. a total of 5,632 sera were collected from 43 species of migrants during spring (april-june), of which 34 (0.61%) comprised of 14 species tested positive by enzyme immunoassay; only 10 were confirmed by p ... | 2010 | 20889869 |
| coccidia in passerines from the nevado de toluca national park, mexico. | in this study, we found unsporulated coccidia oocysts in passerines from the nevado de toluca national park, mexico. we captured birds and took samples of their droppings during three field visits. we examined a total of 72 fecal samples and found unsporulated coccidia oocysts in 10 samples from five passerine species: atlapetes pileatus (3), cardelina ruber (1), mniotilta varia (1), oreothlypis celata (2) and regulus calendula (3). this appears to be the first recorded study of unsporulated coc ... | 2014 | 26204037 |
| postbreeding elevational movements of western songbirds in northern california and southern oregon. | migratory species employ a variety of strategies to meet energetic demands of postbreeding molt. as such, at least a few species of western neotropical migrants are known to undergo short-distance upslope movements to locations where adults molt body and flight feathers (altitudinal molt migration). given inherent difficulties in measuring subtle movements of birds occurring in western mountains, we believe that altitudinal molt migration may be a common yet poorly documented phenomenon. to exam ... | 2017 | 29043031 |
| seasonal and population variation in male testosterone levels in breeding orange-crowned warblers (vermivora celata). | comparative hormone studies can reveal how physiology underlies life history variation. here, we examined seasonal variation in plasma testosterone concentration between populations of male orange-crowned warblers (vermivora celata) breeding in fairbanks, alaska (v. c. celata) and on santa catalina island, california (v. c. sordida). these populations face different ecological constraints and exhibit different life histories. alaska birds have a short breeding season, low annual adult survival, ... | 2010 | 20420840 |
| partitioning the sources of demographic variation reveals density-dependent nest predation in an island bird population. | ecological factors often shape demography through multiple mechanisms, making it difficult to identify the sources of demographic variation. in particular, conspecific density can influence both the strength of competition and the predation rate, but density-dependent competition has received more attention, particularly among terrestrial vertebrates and in island populations. a better understanding of how both competition and predation contribute to density-dependent variation in fecundity can ... | 2014 | 25077023 |
| statistical modeling of patterns in annual reproductive rates. | reproduction by individuals is typically recorded as count data (e.g., number of fledglings from a nest or inflorescences on a plant) and commonly modeled using poisson or negative binomial distributions, which assume that variance is greater than or equal to the mean. however, distributions of reproductive effort are often underdispersed (i.e., variance < mean). when used in hypothesis tests, models that ignore underdispersion will be overly conservative and may fail to detect significant patte ... | 2019 | 30916779 |
| molecular evidence that the channel islands populations of the orange-crowned warbler (oreothlypis celata; aves: passeriformes: parulidae) represent a distinct evolutionary lineage. | we used molecular data to assess the degree of genetic divergence across the breeding range of the orange-crowned warbler (oreothlypis celata) in western north america with particular focus on characterizing the divergence between o. celata populations on the mainland of southern california and on the channel islands. we obtained sequences of the mitochondrial gene nd2 and genotypes at ten microsatellite data for 192 o. celata from populations spanning all four recognized subspecies. we recovere ... | 2019 | 31404458 |
| double keystone bird in a keystone species complex. | species in a colorado subalpine ecosystem show subtle interdependences. red-naped sapsuckers play two distinct keystone roles. they excavate nest cavities in fungus-infected aspens that are required as nest sites by two species of swallows, and they drill sap wells into willows that provide abundant nourishment for themselves, hummingbirds, orange-crowned warblers, chipmunks, and an array of other sap robbers. the swallows thus depend on, and the sap robbers benefit from, a keystone species comp ... | 1993 | 11607351 |