Klamath Falls, OR, United States
Klamath Falls, OR, United States

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Craig D.P.,Willamette University | Larson K.,Klamath Bird Observatory | Larson K.,Umeå University
Waterbirds | Year: 2017

Migratory connectivity of Caspian Terns (Hydroprogne caspia) was investigated using individuals marked in North America between 1922 and 2015. The results support recent genetic work describing three breeding regions (Pacific, Great Lakes, and Central Canada). Further, our results show strong migratory connectivity of Pacific breeders to wintering regions in central and western Mexico, and connectivity of Great Lakes breeders to wintering regions in the Gulf of Mexico and Caribbean. This integrated picture of demographic connectivity throughout North America should help in planning more effective management of the species.

Betts M.G.,Oregon State University | Hagar J.C.,U.S. Geological Survey | Rivers J.W.,Oregon State University | Alexander J.D.,Klamath Bird Observatory | And 2 more authors.
Ecological Applications | Year: 2010

Recent declines in broadleaf-dominated, early-seral forest globally as a function of intensive forest management and/or fire suppression have raised concern about the viability of populations dependent on such forest types. However, quantitative information about the strength and direction of species associations with broadleaf cover at landscape scales are rare. Uncovering such habitat relationships is essential for understanding the demography of species and in developing sound conservation strategies. It is particularly important to detect points in habitat reduction where rates of population decline may accelerate or the likelihood of species occurrence drops rapidly (i.e., thresholds). Here, we use a large avian point-count data set (N = 4375) from southwestern and northwestern Oregon along with segmented logistic regression to test for thresholds in forest bird occurrence as a function of broadleaf forest and early-seral broadleaf forest at local (150-m radius) and landscape (500-2000-m radius) scales. All 12 bird species examined showed positive responses to either broadleaf forest in general, and/or early-seral broadleaf forest. However, regional variation in species response to these conditions was high. We found considerable evidence for landscape thresholds in bird species occurrence as a function of broadleaf cover; threshold models received substantially greater support than linear models for eight of 12 species. Landscape thresholds in broadleaf forest ranged broadly from 1.35% to 24.55% mean canopy cover. Early-seral broadleaf thresholds tended to be much lower (0.22-1.87%). We found a strong negative relationship between the strength of species association with early-seral broadleaf forest and 42-year bird population trends; species most associated with this forest type have declined at the greatest rates. Taken together, these results provide the first support for the hypothesis that reductions in broadleaf-dominated early-seral forest due to succession and intensive forest management have led to population declines of constituent species in the Pacific northwestern United States. Forest management treatments that maintain or restore even small amounts of broadleaf vegetation could mitigate further declines. © 2010 by the Ecological Society of America.

Wolfe J.D.,Pacific Southwest Research Station | Wolfe J.D.,Klamath Bird Observatory | Wolfe J.D.,Louisiana State University | Johnson E.I.,Louisiana State University | Terrill R.S.,Louisiana State University
Auk | Year: 2014

Howell et al. (2003) published an innovative augmentation to terminology proposed by Humphrey and Parkes (1959) that classified bird molt on the basis of perceived evolutionary relationships. Despite apparent universal applicability, Howell et al.'s (2003) proposed terminological changes were met with criticism that cited a failure to verify the evolutionary relationships of molt and an inability to recognize homologous molts even within closely related taxa. Eleven years after Howell et al. (2003), we revisit arguments against a terminological system of molt based on evolutionary relationships, suggest an analytical framework to satisfactorily respond to critics, clarify terminology, and consider how to study molt variation within an evolutionary framework. © 2014 American Ornithologists' Union.

Shirley S.M.,Oregon State University | Yang Z.,Oregon State University | Hutchinson R.A.,Oregon State University | Alexander J.D.,Klamath Bird Observatory | And 2 more authors.
Diversity and Distributions | Year: 2013

Aim: Assessing the influence of land cover in species distribution modelling is limited by the availability of fine-resolution land-cover data appropriate for most species responses. Remote-sensing technology offers great potential for predicting species distributions at large scales, but the cost and required expertise are prohibitive for many applications. We test the usefulness of freely available raw remote-sensing reflectance data in predicting species distributions of 40 commonly occurring bird species in western Oregon. Location: Central Coast Range, Cascade and Klamath Mountains Oregon, USA. Methods: Information on bird observations was collected from 4598 fixed-radius point counts. Reflectance data were obtained using 30-m resolution Landsat imagery summarized at scales of 150, 500, 1000 and 2000 m. We used boosted regression tree (BRT) models to analyse relationships between distributions of birds and reflectance values and evaluated prediction performance of the models using area under the receiver operating characteristic curve (AUC) values. Results: Prediction success of models using all reflectance values was high (mean AUC = 0.79 ± 0.10 SD). Further, model performance using individual reflectance bands exceeded those that used only Normalized Difference Vegetation Index (NDVI). The relative influence of band 4 predictors was highest, indicating the importance of variables associated with vegetation biomass and photosynthetic activity. Across spatial scales, the average influence of predictors at the 2000 m scale was greatest. Main Conclusions: We demonstrate that unclassified remote-sensing imagery can be used to produce species distribution models with high prediction success. Our study is the first to identify general patterns in the usefulness of spectral reflectances for species distribution modelling of multiple species. We conclude that raw Landsat Thematic Mapper data will be particularly useful in species distribution models when high-resolution predictions are required, including habitat change detection studies, identification of fine-scale biodiversity hotspots and reserve design. © 2013 John Wiley & Sons Ltd.

Wolfe J.D.,U.S. Department of Agriculture | Wolfe J.D.,Klamath Bird Observatory | Ralph C.J.,U.S. Department of Agriculture | Ralph C.J.,Klamath Bird Observatory | Elizondo P.,Instituto Nacional Of Biodiversidad Inbio
Oecologia | Year: 2015

The effects of habitat alteration and climatic instability have resulted in the loss of bird populations throughout the globe. Tropical birds in particular may be sensitive to climate and habitat change because of their niche specialization, often sedentary nature, and unique life-cycle phenologies. Despite the potential influence of habitat and climatic interactions on tropical birds, we lack comparisons of avian demographics from variably aged forests subject to different climatic phenomena. Here, we measured relationships between forest type and climatic perturbations on White-collared Manakin (Manacus candei), a frugivorous tropical bird, by using 12 years of capture data in young and mature forests in northeastern Costa Rica. We used Cormack–Jolly–Seber models and an analysis of deviance to contrast the influence of the El Niño Southern Oscillation (ENSO) on manakin survival. We found that ENSO had little effect on manakin survival in mature forests. Conversely, in young forests, ENSO explained 79 % of the variation where dry El Niño events negatively influenced manikin survival. We believe mature forest mitigated negative effects of dry El Niño periods and can serve as refugia for some species by buffering birds from climatic instability. Our results represent the first published documentation that ENSO influences the survival of a resident Neotropic landbird. © 2015, Springer-Verlag Berlin Heidelberg (outside the USA).

Seavy N.E.,University of Florida | Seavy N.E.,Klamath Bird Observatory | Alexander J.D.,Klamath Bird Observatory
International Journal of Wildland Fire | Year: 2014

We used 1 year of pre-fire and 4 years of post-fire data to quantify changes in the occurrence of birds at burned and unburned sites in a southern Oregon watershed after a 2500-ha wildfire. Our objectives were to identify bird species that increased or decreased as a result of this mixed-severity fire. Of the 27 species we investigated, we found evidence for fire-induced changes in the proportion of sites occupied by 13 species. Of these, most (8 species) were species that occurred at fewer sites after the fire than before. These changes were consistent with changes in vegetation composition, which included a decrease in the cover of conifer species and an increase in the cover of broadleaf species. To evaluate the effect of the fire on other ecological conditions, we compared the abundance of nest predators and potential prey items (arthropod biomass) between burned and unburned areas in the 3rd and 4th years after the fire. We found little evidence that the abundance of nest predators differed between burned and unburned areas in either year. There was, however, substantial spatial and temporal variation in arthropod abundance. Hemipteran and coleopteran biomass was greater in burned areas in both the 3rd and 4th year after the fire, and overall arthropod biomass was greater in the 4th year after the fire. The spatial and temporal variability in the bird response to this fire illustrates the importance of before-after-control-impact and multi-year studies for understanding the effects of large-scale disturbances on avian community composition. © IAWF 2014.

Newell F.L.,Ohio State University | Newell F.L.,Klamath Bird Observatory | Rodewald A.D.,Ohio State University
Journal of Wildlife Management | Year: 2012

Interest in regenerating oaks (Quercus spp.) has promoted use of partial harvesting techniques that create an open forest structure. From 2007 to 2009, we studied songbirds in mixed-oak forests in southeastern Ohio, comparing shelterwoods recently harvested to 50% stocking and closed-canopy mature second-growth. We surveyed birds using distance-based methods (56 line transects in 18 stands at 4 forests). We intensively investigated suitability of shelterwoods for canopy-nesting species by examining habitat preferences, as measured by settlement patterns, age distributions, and site fidelity; we also examined nesting success. Several midstory and ground-nesting species were 26-73% less abundant in shelterwood than unharvested stands, whereas shrub-nesting species increased >100% several years post-harvesting. Canopy-nesting species were 31-98% more abundant in shelterwoods, but cerulean warbler (Setophaga cerulea) responses varied by forest. Patterns of settlement and site fidelity were generally similar among stands. Proportions of young males were actually greater for several species in shelterwood than unharvested stands, which may have been a consequence of young birds colonizing newly created (or improved) habitat. Even in our predominantly forested study system, nesting success (>700 nests) was low, ranging from 15% to 19% for yellow-throated vireos (Vireo flavifrons) and cerulean warblers, to 27-36% for scarlet tanagers, blue-gray gnatcatchers (Polioptila caerulea) and eastern wood-pewees (Contopus virens). However, nest survival did not differ between shelterwood and unharvested stands, possibly because numbers of avian predators did not change with harvesting. Despite increased numbers of brown-headed cowbirds (Molothrus ater) in shelterwoods, only 2% of canopy nests in which young could be identified were parasitized. Although these results suggest shelterwood harvests containing abundant overstory trees can provide short-term breeding habitat for canopy songbirds, long-term responses of birds to partial harvesting may differ from those documented here depending on different management options employed. Management for oak regeneration will typically remove all overstory trees later in the cutting cycle, initially resulting in loss of nesting substrates and hence breeding habitat for canopy songbirds. © 2011 The Wildlife Society.

Ausprey I.J.,Ohio State University | Ausprey I.J.,Klamath Bird Observatory | Rodewald A.D.,Ohio State University
Auk | Year: 2011

Despite recent increases in the number of demographic studies of birds in urban environments, the postfledging period remains poorly understood. Because novel ecological factors, including changes in predator abundance and invasive exotic shrubs, are associated with urbanization, we asked (1) how does postfledging survivorship vary across a rural-to-urban landscape gradient and (2) to what extent does Amur Honeysuckle (Lonicera maackii), an invasive exotic shrub, influence patterns of survivorship and habitat selection? During the 2008 and 2009 breeding seasons, we placed radiotransmitters on fledgling Northern Cardinals (Cardinalis cardinalis; n = 45) and Acadian Flycatchers (Empidonax virescens; n = 31) that occupied riparian forest stands embedded within a rural-to-urban landscape gradient in central Ohio, USA. Predation was the primary cause of fledgling mortality for both species, but cumulative survivorship (± SE) for Acadian Flycatchers (0.720 ± 0.097; 22 days) was 1.6 × that of Northern Cardinals (0.440 ± 0.077; 71 days). Survivorship across the entire postfledging period was not associated with urbanization, but during the initial 3 days after fledging, when mortality rates were highest, Northern Cardinal survivorship was positively related to urbanization. Northern Cardinals strongly selected for complex understory vegetation that was positively associated with survivorship, but survival was not related specifically to cover by Amur Honeysuckle. Contrary to assumptions that postfledging survival declines as landscapes urbanize, our results suggest that urban forests may provide suitable habitat for juvenile birds living within metropolitan areas.

Wolfe J.D.,Louisiana State University | Wolfe J.D.,Humboldt State University | Johnson M.D.,Humboldt State University | Ralph C.J.,U.S. Department of Agriculture | Ralph C.J.,Klamath Bird Observatory
PLoS ONE | Year: 2014

Nearctic-neotropic migrant birds need to replenish energy reserves during stopover periods to successfully complete their semiannual movements. In this study we used linear models to examine the habitat use of 11 migrant species in northeastern Costa Rica to better understand the influence of food and structural resources on the presence of birds during stopover periods. Our models indicated that frugivorous migrants primarily used food abundance, while insectivorous migrants chiefly used vegetation structure as cues for habitat use during stopover. In addition to habitat use models, we documented fruiting plant phenology and found a general relationship between migrant arrival and the timing of ripe fruit availability. Our results suggest that insectivorous migrants probably rely on structural features when using habitat because it may be inherently difficult to assess cryptic-arthropod availability during a short period of time in a novel habitat, such as stopover periods.

PubMed | Klamath Bird Observatory, National Park Service and U.S. Department of Agriculture
Type: Journal Article | Journal: PloS one | Year: 2016

We examined avian community ecology in the Klamath Ecoregion and determined that individual bird species co-exist spatially to form 29 statistically distinguishable bird groups. We identified climate, geography, and vegetation metrics that are correlated with these 29 bird groups at three scales: Klamath Ecoregion, vegetation formation (agriculture, conifer, mixed conifer/hardwood, shrubland), and National Park Service unit. Two climate variables (breeding season mean temperature and temperature range) and one geography variable (elevation) were correlated at all scales, suggesting that for some vegetation formations and park units there is sufficient variation in climate and geography to be an important driver of bird communities, a level of variation we expected only at the broader scale. We found vegetation to be important at all scales, with coarse metrics (environmental site potential and existing vegetation formation) meaningful across all scales and structural vegetation patterns (e.g. succession, disturbance) important only at the scale of vegetation formation or park unit. Additionally, we examined how well six National Park Service units represent bird communities in the broader Klamath Ecoregion. Park units are inclusive of most bird communities with the exception of the oak woodland community; mature conifer forests are well represented, primarily associated with conifer canopy and lacking multi-layered structure. Identifying environmental factors that shape bird communities at three scales within this region is important; such insights can inform local and regional land management decisions necessary to ensure bird conservation in this globally significant region.

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