USGS field technician photographing bumble bees captured during monitoring surveys at Logan Pass, Glacier National Park, Montana.
Tabitha Graves, Ph.D.
I answer applied research questions at the intersection of wildlife biology, landscape ecology, and statistics.
Research Interests
My work falls under three broad themes: (1) understand the influence of humans and associated land use impacts on wildlife distributions, densities, and related processes at local and landscape scales, (2) develop new analytical tools that address the influence of landscape features on animals at the sub-population and population scales, and (3) improve efficiency of research and monitoring through optimal study design. I have >15 years experience studying grizzly bears, bighorn sheep, elk, and the development of novel and integrated analyses of habitat use, connectivity, migration, and genetics, all very applied work. I have also assisted with projects studying black bears, wolverines, mountain goats, wolves, lynx, kinkajou, loons, hawks, owls, riparian vegetation, pika, and sugar pine.
Current projects
- Chronic wasting disease- evaluating changes in density and contacts across multiple cervid populations
- Assessing current and changing forage for elk and mule deer with climate change
- Assessing connectivity and migration in and around Glacier National Park (GNP)
- Optimal monitoring of wildlife with occupancy models
- Pollinator communities and Western bumble bee assessment on BLM lands in Montana and the Dakotas, in GNP, and across the west
- Mountain goat and bighorn sheep abundance, trend, population structure, and habitat
- Spatial capture recapture approaches
- Water to Wildlife: Connecting changes in water to vegetation to wildlife across 3 northwest parks
- Evaluating potential impacts of climate change on berry plant abundance and production
Professional Experience
Research Ecologist, USGS Northern Rocky Mountain Science Center: 2/10/14-present
David H. Smith Post-doctoral Conservation Research Fellow: 7/12 – 2/14
Education and Certifications
PhD. 2012. Northern Arizona University. Dissertation Title: Spatial ecology of grizzly bears in northwestern Montana and estimating resistance to gene flow
M.S. Wildlife Biology. 2002. University of Montana
Honors B.A. German Literature with distinction. 1995. University of Wisconsin-Madison
Science and Products
Using Pollinator Environmental DNA to Assess the Ecological Resilience of America’s Grasslands
From Water to Wildlife: Linking Water Timing and Availability to Meadows and Wildlife in a Changing Climate
Developing Tools to Evaluate Chronic Wasting Disease Transmission Risk
USGS Chronic Wasting Disease Research at NOROCK
Western Bumble Bee and Native Pollinator Research
Predicting Future Forage Conditions for Elk and Mule Deer in Montana and Wyoming
NOROCK Large Carnivore Research Program
Science in Glacier National Park
Long Term Research in northwest Montana
Grizzly Bear Family Tree
Grizzly Bear Dispersal
Predicting changes in Bear Foods
Black bear (Ursus Americanus) spatial capture recapture dataset in and near Glacier National Park, Montana, USA, 2004
Glacier Waterton International Peace Park bighorn sheep (Ovis canadensis) habitat selection, 2002-2012
Glacier Waterton International Peace Park bighorn sheep (Ovis canadensis), 2002-2012
Age ratios and landscape change covariates for mule deer (Odocoileus hemionus) herd units in Wyoming, USA, 1985-2019
Downscaled western bumble bee predicted occupancy for 2020, western conterminous United States.
Occurrence data of the western bumble bee from 1998 to 2020 across the western United States
Wyoming statewide time-stamped oil and gas activity, 1900-2020
Bumblebee Surveys in Montana, North Dakota, South Dakota, and Nevada, USA (ver. 2.0, April 2023)
Neonicotinoid nitroguanidine group insecticide application rates estimated across the western conterminous United States, 2008 to 2014
Western bumble bee predicted occupancy (1998, 2020) and future projections (2050s), western conterminous United States
Daily 30-m fractional snow covered area and summary stats for the National Elk Refuge, Wyoming from 2015 to 2020
Historical trend analysis of phenology dates across the Western US from 1982 to 2016
USGS field technician photographing bumble bees captured during monitoring surveys at Logan Pass, Glacier National Park, Montana.
Many bumble bee species have declined in recent decades due to changes in habitat, climate, and pressures from pathogens, pesticides and introduced species. The western bumble bee, once common throughout western North America, is a species of concern and is being considered for listing by the U.S. Fish and Wildlife Service under the Endangered Species Act.
Many bumble bee species have declined in recent decades due to changes in habitat, climate, and pressures from pathogens, pesticides and introduced species. The western bumble bee, once common throughout western North America, is a species of concern and is being considered for listing by the U.S. Fish and Wildlife Service under the Endangered Species Act.
The USGS studies bighorn sheep movements, population structures, and habitat use in and near Glacier National Park.
The USGS studies bighorn sheep movements, population structures, and habitat use in and near Glacier National Park.
Evaluating density-weighted connectivity of black bears (Ursus americanus) in Glacier National Park with spatial capture–recapture models
Quantifying effectiveness and best practices for bumblebee identification from photographs
Bighorn sheep associations: Understanding tradeoffs of sociality and implications for disease transmission
Ecological significance of Wild Huckleberries (Vaccinium membranaceum)
Recent and future declines of a historically widespread pollinator linked to climate, land cover, and pesticides
The acute decline in global biodiversity includes not only the loss of rare species, but also the rapid collapse of common species across many different taxa. The loss of pollinating insects is of particular concern because of the ecological and economic values these species provide. The western bumble bee (Bombus occidentalis) was once common in western North America, but this species has become
Final Report: Predicting impacts to mule deer of changing forage using landscape surface phenology metrics
Precision and bias of spatial capture–recapture estimates: A multi-site, multi-year Utah black bear case study
Eyes on the herd: Quantifying ungulate density from satellite, unmanned aerial systems, and GPScollar data
Average kinship within bighorn sheep populations is associated with connectivity, augmentation, and bottlenecks
Genetic attributes and research interests
U.S. Geological Survey science for the Wyoming Landscape Conservation Initiative—2018 annual report
The smell of success: Reproductive success related to rub behavior in brown bears
Non-USGS Publications**
**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
WildAgg: an R package to estimate and visualize wildlife aggregation data
Science and Products
- Science
Filter Total Items: 15
Using Pollinator Environmental DNA to Assess the Ecological Resilience of America’s Grasslands
Scientists from six USGS science centers are collaborating with USDA, university, and Tribal partners, and Department of the Interior land managers, to assess the status of pollinator communities and the distribution of species of conservation concern using environmental DNA. These methods will be used to improve assessments of habitat quality and pollinator responses to restoration, including...BySpecies Management Research Program, Eastern Ecological Science Center, Forest and Rangeland Ecosystem Science Center, Great Lakes Science Center, Northern Prairie Wildlife Research Center, Northern Rocky Mountain Science Center, Upper Midwest Environmental Sciences Center, Pacific Northwest Environmental DNA LaboratoryFrom Water to Wildlife: Linking Water Timing and Availability to Meadows and Wildlife in a Changing Climate
Mountain meadows in the western United States provide key habitats for many plant and wildlife species, many of which rely exclusively on these areas. Mountain meadows are also treasured by the public and provide beautiful areas to view wildflowers and wildlife on public lands such as national parks. However, mountain ecosystems are expected to be disproportionately affected by climate change. TheDeveloping Tools to Evaluate Chronic Wasting Disease Transmission Risk
Chronic Wasting Disease (CWD) infects and kills ungulates (deer, elk, moose), and has been spreading across North America for the past 20 years. Some ungulate populations have declined because of CWD and there are no viable vaccines or treatments for this disease. Therefore, tools that assist wildlife managers in preventing and mitigating CWD can be powerful assets in protecting our nation’s big...USGS Chronic Wasting Disease Research at NOROCK
Over the past 20 years, chronic wasting disease (CWD) in Wyoming has been spreading slowly outward from the southeastern corner of the state toward the Greater Yellowstone Area and Wyoming's elk feed grounds, where more than 24,000 elk are supplementally fed each winter.Western Bumble Bee and Native Pollinator Research
The western bumble bee was historically one of the most common bumble bees across the western U.S. and Canada. However, our research and others found it has declined substantially across its range and the U.S. Fish and Wildlife Service is considering it for listing under the Endangered Species Act. Bureau of Land Management, National Park Service, and other land managers need information to inform...Predicting Future Forage Conditions for Elk and Mule Deer in Montana and Wyoming
Improving the quality of habitat for western big-game species, such as elk and mule deer, was identified as a priority by the Department of the Interior in 2018. Maintaining healthy herds not only supports the ecosystems where these species are found, but also the hunting and wildlife watching communities. For example, in Wyoming, big game hunting contributed over $300 million to the state’s econoNOROCK Large Carnivore Research Program
NOROCK has substantial expertise in large carnivore research, primarily involving species listed as Threatened or Endangered. NOROCK’s Large Carnivore Research Program includes scientists from NOROCK’s Headquarters, West Glacier Field Station, and the Southern Appalachian Field Station. Studies are conducted in a wide variety of landscapes throughout the U.S., as well as international research...Science in Glacier National Park
Glacier National Park (GNP) is considered a stronghold for a large diversity of plant and animal species and harbors some of the last remaining populations of threatened and endangered species such as grizzly bear and bull trout, as well as non threatened keystone species such as bighorn sheep and black bear. The mountain ecosystems of GNP that support these species are dynamic and influenced by...Long Term Research in northwest Montana
The Northern Continental Divide Ecosystem (NCDE) in northwest Montana is one of the last strongholds of the grizzly bear in the lower 48 states. Of the six established grizzly bear recovery zones, the NCDE is the third largest in area, potentially harboring the greatest number of grizzly bears, and is the only zone contiguous to a strong Canadian population. However, little information exists...Grizzly Bear Family Tree
Building a family tree of grizzly bears can both satisfy our natural curiosity about bear society and answer many ecologically important questions about the ways bears interact with each other and the landscape.Grizzly Bear Dispersal
This work has two components. First, we developed a method to use our family tree data to examine dispersal. Next, we would like to apply this method to our updated and more complete family tree to improve our understanding of how grizzly bears disperse.Predicting changes in Bear Foods
Huckleberries are central to the diets of bears, grouse, and other animals, as well as being a cultural and food resource for humans. Approximately 15% of the diet of bears in the Whitefish range and Glacier National Park is huckleberries, and huckleberries help bears gain weight for hibernation. Changes in climate lead to changes in vegetation phenology, productivity, and quality that may... - Data
Filter Total Items: 20
Black bear (Ursus Americanus) spatial capture recapture dataset in and near Glacier National Park, Montana, USA, 2004
Tabular and raster data containing spatial capture recapture records for male and female black bears (Ursus americanus) in Glacier National Park and surrounding landscape collected from June - October 2004 and associated tabular data files required for analysis of data with spatial capture connectivity models and raster data describing the ouput from SCR models. Associated tables and rasters incluGlacier Waterton International Peace Park bighorn sheep (Ovis canadensis) habitat selection, 2002-2012
Output of analysis describing habitat selection, the location of contacts and the intersection of the two. Based on GPS collar data from 2002 to 2011.Glacier Waterton International Peace Park bighorn sheep (Ovis canadensis), 2002-2012
From 2002 to 2011, 94 bighorn sheep were collared to collect GPS locations for approximately a year.Age ratios and landscape change covariates for mule deer (Odocoileus hemionus) herd units in Wyoming, USA, 1985-2019
Sagebrush ecosystems and wildlife that depend on them are under pressure from development, changing climate, as well as natural and human-caused disturbance. Mule deer (Odocoileus hemionus) are of particular concern due to population declines across many western states. We initiated a study to evaluate landscape-level changes ( disturbances, habitat treatments, development, and climate change) inDownscaled western bumble bee predicted occupancy for 2020, western conterminous United States.
This data represents occupancy predictions for western bumble bee in 2020 across the western conterminous United States. This product is a 30-meter resolution downscaled version of previously published occupancy layers for the western bumble bee. For more information on original publications, see the publication listed in the Larger Works Cited Section.Occurrence data of the western bumble bee from 1998 to 2020 across the western United States
These raw survey data and associated explanatory covariates were used to model western bumble bee occupancy across the western conterminous United States from 1998 to 2020. These data underlie the analyses found in the publication of “Recent and future declines of a historically widespread pollinator linked to climate, land cover, and pesticides” by Janousek et al. 2023 in the Proceedings of the NWyoming statewide time-stamped oil and gas activity, 1900-2020
The Wyoming statewide time-stamped oil and gas wells shapefile was developed to provide a historical perspective of drilling activity for the Wyoming Landscape Conservation Initiative (WLCI). This product approximates start and stop dates for each well in Wyoming based on database attributes. These data originated from the Wyoming Oil and Gas Conservation Commission (WOGCC). Data represent 120 yeaBumblebee Surveys in Montana, North Dakota, South Dakota, and Nevada, USA (ver. 2.0, April 2023)
Bumblebee community surveys used occupancy survey designs primarily across lands managed by the Bureau of Land Management (BLM) and Glacier National Park (GNP). They also include a few surveys in Nevada. These records represent timed surveys that were both successful and unsuccessful in detecting western bumblebees.Neonicotinoid nitroguanidine group insecticide application rates estimated across the western conterminous United States, 2008 to 2014
These data represents annual estimates of neonicotinoid nitroguanidine group insecticide application rates across the western conterminous United States from 2008 to 2014. This product contains seven raster layers (appearing as separate bands in a multi-band raster). Each band represents one year of the data beginning in 2008. Estimates are generated by pairing crop specific application rates of nWestern bumble bee predicted occupancy (1998, 2020) and future projections (2050s), western conterminous United States
These data represent occupancy estimates for western bumble bee across the western conterminous United States. This product contains five raster layers (appearing as separate bands in a multi-band raster). The first two bands represent the predicted occupancy of western bumble bee in 1998 and 2020. We modeled western bumble bee occupancy as a function of climate and land cover. The last three bandDaily 30-m fractional snow covered area and summary stats for the National Elk Refuge, Wyoming from 2015 to 2020
This dataset contains daily fractional snow covered area (fSCA) at 30-m spatial resolution from August 1, 2015 - May 15, 2020 (five winters) for the National Elk Refuge in Wyoming, USA. The following summary statistics are also included: date of snow accumulation, date of snow melt, number of days in year with snow on ground, and percentage of "winter days" in year with snow on ground. The SNOWARPHistorical trend analysis of phenology dates across the Western US from 1982 to 2016
These data represent key phenology trends across the western United States from 1982-2016. Using two remote sensing datasets, CMGLSP and VIPPHEN-EVI2, trends were calculated for four phenology variables: Start of Season (SOS), Peak Instantaneous Rate of Green-Up Date (PIRGd), Peak of Season (POS), and End of Season (EOS). The Theil-Sen slope and standard deviation were applied to the phenology met - Multimedia
Photographing bumble bees
USGS field technician photographing bumble bees captured during monitoring surveys at Logan Pass, Glacier National Park, Montana.
USGS field technician photographing bumble bees captured during monitoring surveys at Logan Pass, Glacier National Park, Montana.
Western Bumble BeeMany bumble bee species have declined in recent decades due to changes in habitat, climate, and pressures from pathogens, pesticides and introduced species. The western bumble bee, once common throughout western North America, is a species of concern and is being considered for listing by the U.S. Fish and Wildlife Service under the Endangered Species Act.
Many bumble bee species have declined in recent decades due to changes in habitat, climate, and pressures from pathogens, pesticides and introduced species. The western bumble bee, once common throughout western North America, is a species of concern and is being considered for listing by the U.S. Fish and Wildlife Service under the Endangered Species Act.
Bighorn Sheep RamThe USGS studies bighorn sheep movements, population structures, and habitat use in and near Glacier National Park.
The USGS studies bighorn sheep movements, population structures, and habitat use in and near Glacier National Park.
- Publications
Filter Total Items: 32
Evaluating density-weighted connectivity of black bears (Ursus americanus) in Glacier National Park with spatial capture–recapture models
BackgroundImproved understanding of wildlife population connectivity among protected area networks can support effective planning for the persistence of wildlife populations in the face of land use and climate change. Common approaches to estimating connectivity often rely on small samples of individuals without considering the spatial structure of populations, leading to limited understanding ofAuthorsSarah L Carroll, Greta M Schmidt, John S. Waller, Tabitha GravesQuantifying effectiveness and best practices for bumblebee identification from photographs
Understanding pollinator networks requires species level data on pollinators. New photographic approaches to identification provide avenues to data collection that reduce impacts on declining bumblebee species, but limited research has addressed their accuracy. Using blind identification of 1418 photographed bees, of which 561 had paired specimens, we assessed identification and agreement across 2AuthorsAnne Colgan, Richard G. Hatfield, Amy Dolan, Wendy Velman, Rebecca Newton, Tabitha GravesBighorn sheep associations: Understanding tradeoffs of sociality and implications for disease transmission
Sociality directly influences mating success, survival rates, and disease, but ultimately likely evolved for its fitness benefits in a challenging environment. The tradeoffs between the costs and benefits of sociality can operate at multiple scales, resulting in different interpretations of animal behavior. We investigated the influence of intrinsic (e.g., relatedness, age) and extrinsic factors (AuthorsMarie Tosa, Mark Biel, Tabitha A. GravesEcological significance of Wild Huckleberries (Vaccinium membranaceum)
Wild huckleberry (Vaccinium globare/membranaceum complex) is a keystone species in the Pacific Northwest of the United States. The fruits are a primary food source for grizzly bears and other wildlife, as well as an important traditional and contemporary human food. Huckleberry shrubs also provide cover and nesting habitat for many animal species, including small mammals and birds. The flowers proAuthorsJanene Lichtenberg, Tabitha GravesRecent and future declines of a historically widespread pollinator linked to climate, land cover, and pesticides
The acute decline in global biodiversity includes not only the loss of rare species, but also the rapid collapse of common species across many different taxa. The loss of pollinating insects is of particular concern because of the ecological and economic values these species provide. The western bumble bee (Bombus occidentalis) was once common in western North America, but this species has become
AuthorsWilliam Michael Janousek, Margaret R. Douglas, Syd Cannings, Marion Clement, Casey Delphia, Jeffrey Everett, Richard G. Hatfield, Douglas A. Keinath, Jonathan B Koch, Lindsie M. McCabe, John Michael Mola, Jane Ogilvie, Imtiaz Rangwala, Leif L Richardson, Ashley T. Rohde, James P. Strange, Lusha M. Tronstad, Tabitha GravesFinal Report: Predicting impacts to mule deer of changing forage using landscape surface phenology metrics
No abstract available.AuthorsTabitha GravesPrecision and bias of spatial capture–recapture estimates: A multi-site, multi-year Utah black bear case study
Spatial capture–recapture (SCR) models are powerful analytical tools that have become the standard for estimating abundance and density of wild animal populations. When sampling populations to implement SCR, the number of unique individuals detected, total recaptures, and unique spatial relocations can be highly variable. These sample sizes influence the precision and accuracy of model parameter eAuthorsGreta M Schmidt, Tabitha Graves, Jordan C Pederson, Sarah L CarrollEyes on the herd: Quantifying ungulate density from satellite, unmanned aerial systems, and GPScollar data
Novel approaches to quantifying density and distributions could help biologists adaptively manage wildlife populations, particularly if methods are accurate, consistent, cost-effective, rapid, and sensitive to change. Such approaches may also improve research on interactions between density and processes of interest, such as disease transmission across multiple populations. We assess how satelliteAuthorsTabitha Graves, Michael Yarnall, Aaron N. Johnston, Todd M. Preston, Geneva W. Chong, Eric K Cole, William Michael Janousek, Paul C. CrossAverage kinship within bighorn sheep populations is associated with connectivity, augmentation, and bottlenecks
Understanding the influence of population attributes on genetic diversity is important to advancement of biological conservation. Because bighorn sheep (Ovis canadensis) populations vary in size and management history, the species provides a unique opportunity to observe the response of average pairwise kinship, inversely related to genetic diversity, to a spectrum of natural and management influeAuthorsElizabeth P Flesch, Tabitha Graves, Jennifer Thomson, Kelly M. Proffitt, Robert A. GarrottGenetic attributes and research interests
No abstract available.AuthorsElizabeth P Flesch, Tabitha Graves, Robert A. Garrott, Sarah Dewey, Carson ButlerU.S. Geological Survey science for the Wyoming Landscape Conservation Initiative—2018 annual report
The Wyoming Landscape Conservation Initiative (WLCI) was established in 2007 as a collaborative interagency partnership to develop and implement science-based conservation actions. During the past 11 years, partners from U.S. Geological Survey (USGS), State and Federal land management agencies, universities, and the public have collaborated to implement a long-term (more than 10 years) science-basAuthorsPatrick J. Anderson, Cameron L. Aldridge, Jason S. Alexander, Timothy J. Assal, Steven Aulenbach, Zachary H. Bowen, Anna D. Chalfoun, Geneva W. Chong, Holly Copeland, David R. Edmunds, Steve Germaine, Tabitha Graves, Julie A. Heinrichs, Collin G. Homer, Christopher Huber, Aaron N. Johnston, Matthew J. Kauffman, Daniel J. Manier, Ryan R. McShane, Cheryl A. Eddy-Miller, Kirk A. Miller, Adrian P. Monroe, Michael S. O'Donnell, Anna Ortega, Annika W. Walters, Daniel J. Wieferich, Teal B. Wyckoff, Linda ZeigenfussThe smell of success: Reproductive success related to rub behavior in brown bears
Several species of bears are known to rub deliberately against trees and other objects, but little is known about why bears rub. Patterns in rubbing behavior of male and female brown bears (Ursus arctos) suggest that scent marking via rubbing functions to communicate among potential mates or competitors. Using DNA from bear hairs collected from rub objects in southwestern Alberta from 2011–2014 anAuthorsAndrea T. Morehouse, Anne E. Loosen, Tabitha Graves, Mark S. BoyceNon-USGS Publications**
Graves, T.A., S. Farley, M. Goldstein, and C.Servheen. 2007. Identification of functional corridors with movement characteristics of brown bears on the Kenai Peninsula, Alaska. Landscape Ecology.Graves, T.A., S. Farley, and C.Servheen. 2006. Frequency and distribution of highway crossings by Kenai Peninsula brown bears. Wildlife Society Bulletin. 34: 800-808.Graves, T.A. and J. Waller. 2006. Identification of causes of missed fixes in GPS collar on animals. Journal of Wildlife Management. 70: 844-851.**Disclaimer: The views expressed in Non-USGS publications are those of the author and do not represent the views of the USGS, Department of the Interior, or the U.S. Government.
- Software
WildAgg: an R package to estimate and visualize wildlife aggregation data
This package is designed to estimate, summarize, and visualize wildlife aggregation metrics using location information like GPS collar data. The motivation for the development of this package began with two research efforts studying the aggregation and density of elk on the National Elk Refuge, Wyoming (Janousek et al.2021; and Graves et al. 2021). The primary goal of the WildAgg package is to pro - News