Joan C Hagar
Research Wildlife Biologist
Forest and Rangeland Ecosystem Science Center
Email: joan_hagar@usgs.gov
Forest and wildlife ecology
Great Basin pygmy rabbits
Habitat relationships of forest birds
Oregon white oak communities
Restoration of native habitats
Wildlife-habitat relationships
Ph.D. Forest Ecology, Oregon State University, 2004
Science and Products
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Habitat Mapping and Modeling
Accurately quantifying and mapping wildlife habitat is critical to investigations of species distribution and habitat relationships, and can greatly facilitate management of forests for multiple resources. However acquiring field-based, empirical data is often costly and labor intensive. Modeling provides an alternative technique for describing and mapping habitat, but the usefulness of models...
Contacts: Joan C Hagar
Attribution: Ecosystems, Wildlife Program, Forest and Rangeland Ecosystem Science Center (FRESC)
Date published: November 9, 2017
Effects of Management on Wildlife and Habitats
Conifer forests in the Pacific Northwest are biologically and economically important, are intensively managed for multiple uses, and represent a large area in public domain. Therefore, understanding how management of conifer forests affects biodiversity across a range of spatial and temporal scales is critical for land management agencies.
Attribution: Forest and Rangeland Ecosystem Science Center (FRESC)
Ecology of Rare and Declining Species and Communities of Conservation Concern
Special status species and habitats are often sentinels of accelerated ecosystem change and, by definition, are priorities for protection, restoration, or focused management.
Date published: January 1, 2011
Disentangling the Effects of Climate and Landscape Change on Bird Population Trends in the Western U.S. and Canada
Climate change has been implicated in the range shifts and population declines of many species, but the confounding of climate change with other variables, particularly landscape change, hampers inference about causation. Climate envelope models have been used to predict population trends and future distributions, but the reliability of such predictions remains relatively unknown; without...
Attribution: Climate Adaptation Science Centers, Northwest Climate Adaptation Science Center
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Created snag characteristics and cavity-nesting bird associations in the CFIRP stands, McDonald-Dunn Research Forest, Corvallis, OR, USA, 2016
We measured characteristics of 731 snags and quantified foraging and breeding use of snags by birds 25-27 years after their creation, and examined whether different harvest treatments (i.e., group selection, two-story, clearcut) and snag configurations (i.e., scattered and clustered) influenced snag characteristics or avian use for foraging and nesting.
Attribution: Region 9: Columbia-Pacific Northwest, Forest and Rangeland Ecosystem Science Center (FRESC)
Date published: July 19, 2017
Avian abundance and oak mistletoe survey data from the Willamette Valley, Oregon, 2013-2015
This dataset includes two spreadsheets: The "Avian_abundance_oak_mistletoe_bird_data" spreadsheet contains data regarding Oregon White Oak tree (Quercus garryana) measurements. The "Avian_abundance_oak_mistletoe_surveys_data" spreadsheet contains bird survey observations.
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Removal of cattle grazing correlates with increases in vegetation productivity and in abundance of imperiled breeding birds
Livestock grazing is the most prevalent land use practice in the western United States and a widespread cause of degradation of riparian vegetation. Riparian areas provide high-quality habitat for many species of declining migratory breeding birds. We analyzed changes in vegetation and bird abundance at a wildlife refuge in southeastern Oregon...
Poessel, Sharon; Hagar, Joan; Haggerty, Patricia; Katzner, Todd E.
Attribution: Forest and Rangeland Ecosystem Science Center (FRESC), Ecosystems
Herbicides and herbivory interact to drive plant community and crop‐tree establishment
Land management practices often directly alter vegetation structure and composition, but the degree to which ecological processes such as herbivory interact with management to influence biodiversity is less well understood. We hypothesized that large herbivores compound the effects of intensive forest management on early seral plant communities...
Stokely, Thomas D.; Verschuyl, Jake; Hagar, Joan; Betts, Matthew G.
Use of created snags by cavity‐nesting birds across 25 years
Snags are important habitat features for many forest‐dwelling species, so reductions in the number of snags can lead to the loss of biodiversity in forest ecosystems. Intentional snag creation is often used in managed forests to mitigate the long‐term declines of naturally created snags, yet information regarding the use of snags by wildlife...
Barry, Amy M.; Hagar, Joan; Rivers, James W.
Barry, A.M., Hagar, J.C., Rivers, J.W., 2018, Use of created snags by cavity-nesting birds across 25 Years: Journal of Wildlife Management, p. online, https://doi.org/10.1002/jwmg.21489.
Modeling habitat for Marbled Murrelets on the Siuslaw National Forest, Oregon, using lidar data
Habitat models using lidar-derived variables that quantify fine-scale variation in vegetation structure can improve the accuracy of occupancy estimates for canopy-dwelling species over models that use variables derived from other remote sensing techniques. However, the ability of models developed at such a fine spatial scale to maintain accuracy...
Hagar, Joan C.; Aragon, Ramiro; Haggerty, Patricia; Hollenbeck, Jeff P.
Hagar, J.C., Perez, R.A., Haggerty, P., and Hollenbeck, J.P., 2018, Modeling habitat for Marbled Murrelets on the Siuslaw National Forest, Oregon, using lidar data: U.S. Geological Survey Open-File Report 2018–1035, 21 p., https://doi.org/10.3133/ofr20181035.
Long-term dynamics and characteristics of snags created for wildlife habitat
Snags provide essential habitat for numerous organisms and are therefore critical to the long-term maintenance of forest biodiversity. Resource managers often use snag creation to mitigate the purposeful removal of snags at the time of harvest, but information regarding how created snags change over long timescales (>20 y) is absent from...
Barry, A.M., Hagar, J.C., Rivers, J.W., 2017, Long-term dynamics and characteristics of snags created for wildlife habitat: Forest Ecology and Management, v. 403, p. 145-151, https://doi.org/10.1016/j.foreco.2017.07.049.
This dataset includes two spreadsheets: The "Avian_abundance_oak_mistletoe_bird_data" spreadsheet contains data regarding Oregon White Oak tree (Quercus garryana) measurements such as height, diameter and crown volume along with microhabitat data including number of mistletoe infections, number of cavities, amount of dead wood, amount of loose/...
Pritchard, Kyle R.; Hagar, Joan; Shaw, David C.
Pritchard, K.P., Hagar, J.C., Shaw, D.C., 2017, Avian abundance and oak mistletoe survey data from the Willamette Valley, Oregon, 2013-2015: U.S. Geological Survey Data Release, https://doi.org/10.5066/F7H41PMC.
Oak mistletoe (Phoradendron villosum) is linked to microhabitat availability and avian diversity in Oregon white oak (Quercus garryana) woodlands
Mistletoes are parasitic or hemi-parasitic flowering plants that parasitize woody plants around the globe. Important food and cover resources provided by mistletoes have been related to strong patterns of positive association between wildlife diversity and mistletoe density. Mistletoes also create microhabitat features known to be important to...
Pritchard, K.P., Hagar, J.C., Shaw, D.C., 2016, Oak mistletoe (Phoradendron villosum) is linked to microhabitat availability and avian diversity in Oregon white oak (Quercus garryana) woodlands: Botany, p. online, http://dx.doi.org/10.1139/cjb-2016-0249.
North Cascades National Park Service Complex
Natural Resource Condition Assessments (NRCAs) evaluate current conditions for a subset of natural resources and resource indicators in national parks. NRCAs also report on trends in resource condition (when possible), identify critical data gaps, and characterize a general level of confidence for study findings. The resources and indicators...
Hoffman, Robert; Woodward, Andrea; Haggerty, Patricia K.; Jenkins, Kurt J.; Griffin, Paul C.; Adams, M.J.; Hagar, Joan; Cummings, Tonnie; Duriscoe, Dan; Kopper, Karen; Riedel, Jon; Marin, Lelaina; Mauger, Guillaume S; Bumbaco, Karen; Littell, Jeremy S.
Hoffman, Jr., R., Woodward, A., Haggerty, P., Jenkins, K.J., Griffin, P.C., Adams, M.J., Hagar, J., Cummings, T., Duriscoe, D., Kopper, K., Riedel, J., Marin, L., Mauger, G.S., Bumbaco, K., Littell, J.S., 2015, North Cascades National Park Service Complex- Natural Resource condition Assessment: National Park Service NPS/NOCA/NRR—2015/901, p. 390.
Modeling marbled murrelet (Brachyramphus marmoratus) habitat using LiDAR-derived canopy data
LiDAR (Light Detection And Ranging) is an emerging remote-sensing tool that can provide fine-scale data describing vertical complexity of vegetation relevant to species that are responsive to forest structure. We used LiDAR data to estimate occupancy probability for the federally threatened marbled murrelet (Brachyramphus marmoratus) in the Oregon...
Hagar, Joan C.; Eskelson, Bianca N.I.; Haggerty, Patricia K.; Nelson, S. Kim; Vesely, David G.
Modeling marbled murrelet (Brachyramphus marmoratus) habitat using LiDAR-derived canopy data; 2014; Article; Journal; Wildlife Society Bulletin; Hagar, Joan C.; Eskelson, Bianca N. I.; Haggerty, Patricia K.; Nelson, S. Kim; Vesely, David G.
Hoffman, Robert; Woodward, Andrea; Haggerty, Patricia K.; Jenkins, Kurt J.; Griffin, Paul C.; Adams, M.J.; Hagar, Joan; Cummings, Tonnie; Duriscoe, Dan; Kopper, Karen; Riedel, Jon; Samora, Barbara; Marin, Lelaina; Mauger, Guillaume S.; Bumbaco, Karen; Littell, Jeremy S.
Hoffman, Jr., R., Woodward, A., Haggerty, P., Jenkins, K.J., Griffin, P.C., Adams, M.J., Hagar, J., Cummings, T., Duriscoe, D., Kopper, K., Riedel, J., Samora, B., Marin, L., Mauger, G.S., Bumbaco, K., Littell, J.S., 2014, Mount Rainier National Park- Natural Resource Condition Assessment. Natural Resource Report: National Park Service NPS/MORA/NRR--2014/894, p. 380.
Bird-vegetation associations in thinned and unthinned young Douglas-fir forests 10 years after thinning
Quantitative associations between animals and vegetation have long been used as a basis for conservation and management, as well as in formulating predictions about the influence of resource management and climate change on populations. A fundamental assumption embedded in the use of such correlations is that they remain relatively consistent over...
Yegorova, Svetlana; Betts, Matthew G.; Hagar, Joan; Puettmann, Klaus J.
Bird-vegetation associations in thinned and unthinned young Douglas-fir forests 10 years after thinning; 2013; Article; Journal; Forest Ecology and Management; Yegorova, Svetlana; Betts, Matthew G.; Hagar, Joan; Puettmann, Klaus J.
Management, morphological, and environmental factors influencing Douglas-fir bark furrows in the Oregon Coast Range
Many land managers in the Pacific Northwest have the goal of increasing late-successional forest structures. Despite the documented importance of Douglas-fir tree bark structure in forested ecosystems, little is known about factors influencing bark development and how foresters can manage development. This study investigated the relative...
Sheridan, Christopher D.; Puettmann, Klaus J.; Huso, Manuela M.P.; Hagar, Joan C.; Falk, Kristen R.
Management, morphological, and environmental factors influencing Douglas-fir bark furrows in the Oregon Coast Range; 2013; Article; Journal; Western Journal of Applied Forestry; Sheridan, Christopher D.; Puettmann, Klaus J.; Huso, Manuela M. P.; Hagar, Joan C.; Falk, Kristen R.
Pre-USGS Publications
Short-term response of songbirds to experimental thinning of young Douglas-fir forests in the Oregon Cascades
Hagar, J.C., Howlin, S., Ganio, L., 2004, Short-term response of songbirds to experimental thinning of young Douglas-fir forests in the Oregon Cascades: Forest Ecology and Management, v. 199, p. 333-347.
Avifauna in oak woodlands of the Willamette Valley, Oregon
Hagar, J.C., Stern, M.A., 2001, Avifauna in oak woodlands of the Willamette Valley, Oregon: Northwestern Naturalist, v. 82, p. 12-15.
Bird communities in commercially thinned and unthinned Douglas-fir stands of western Oregon
Hagar, J.C., McComb, W.C., Emmingham, W.H., 1996, Bird communities in commercially thinned and unthinned Douglas-fir stands of western Oregon: Wildlife Society Bulletin, v. 24, no. 2, p. 353-366.
Effects of silvicultultural modifications of temperate rainforest on breeding and wintering bird communities, Prince of Wales Island, southeast Alaska
Dellasala, D.A., Hagar, J.C., Engel, K.A., McComb, W.C., Fairbanks, R.L., Campbell, E.G., 1996, Effects of silvicultultural modifications of temperate rainforest on breeding and wintering bird communities, Prince of Wales Island, southeast Alaska: The Condor, v. 98, p. 706-721.
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Oregon Songbirds: Singing for Their Supper in Evergreen Forests
In this episode we sit down with USGS wildlife biologist Joan Hagar and discuss her recent study on songbirds in the Pacific Northwest. New research indicates a possible relationship between reductions in the abundance of some species of songbird and reductions in the amount of deciduous trees in evergreen forests. Join us, as we demonstrate how Oregon songbirds sing for
Attribution: Region 9: Columbia-Pacific Northwest, Oregon Water Science Center, Forest and Rangeland Ecosystem Science Center (FRESC)
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Excluding Grazing has Positive Effects on Riparian Vegetation, Migratory Birds
Livestock grazing can degrade riparian vegetation, altering habitat for many species of declining migratory breeding birds. At Hart Mountain National Antelope Refuge in southeastern Oregon, cattle were removed from riparian areas in 1990 after 120 years of grazing.
Date published: December 11, 2019
New LiDAR Metrics Help Identify Habitat for the Northern Spotted Owl
The development of metrics derived from LiDAR to study forest structure has advanced wildlife-habitat modeling.
Herbicides and Herbivory Interactions Affect Plant Communities and Tree Survival
Land management practices often directly alter vegetation structure and composition, but the degree to which ecological processes such as herbivory are affected is poorly understood.
Attribution: States and Territories, Forest and Rangeland Ecosystem Science Center (FRESC)