Sequential estimates of occupied ranges for grizzly bears in the Greater Yellowstone Ecosystem during 1990–2022 (Dellinger et al. 2023). Range extents are based on methods described in Bjornlie et al. (2014).
Frank T van Manen, Ph.D.
Frank van Manen is an ecologist who blends his research interest in large carnivores with landscape ecology and is the team lead of the Interagency Grizzly Bear Study Team.
Research Interests
Frank's research focus is on 1) grizzly bear and black bear ecology and management, 2) demographic models to inform large carnivore management, 3) resource selection and energy landscapes, 4) wildlife genetics, and 5) international bear conservation.
Formerly, Frank spent 12 years with the USGS Leetown Science Center specializing in responses of mammals to landscape changes, management of large carnivores, and habitat models to support protection and restoration of plants and trees.
For available articles, click on the Publications tab.
Science and Products
Informing Management Options for grizzly bears in a Changing Greater Yellowstone Ecosystem
Project Overview The iconic grizzly bear of the Greater Yellowstone Ecosystem has exhibited a remarkable recovery in response to concerted conservation actions implemented since its listing as threatened under the Endangered Species Act in 1975. However, information regarding the potential effects and timing of climate change in conjunction with increasing human recreation and development will be
The Effects of Climate Variability and Change on Human-Bear Interactions in North America
Negative human-bear interactions are a common problem and management priority for many wildlife agencies in North America. Bears are adaptable to anthropogenic activity and food sources which creates opportunities for conflict with humans, including property damage, livestock depredation, and in severe cases, human injury. Acute climate events and long-term directional climate change can exacerbat
Interagency Grizzly Bear Study Team
The Interagency Grizzly Bear Study Team (IGBST) is an interdisciplinary group of scientists and biologists responsible for long-term monitoring and research efforts on grizzly bears in the Greater Yellowstone Ecosystem (GYE). The team was formed by the Department of the Interior (DOI) in 1973 as a direct result of controversy surrounding the closure of open pit garbage dumps within Yellowstone...
NOROCK 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...
IGBST Grizzly Bear Food Synthesis Report
How to Cite: Interagency Grizzly Bear Study Team. 2013. Response of Yellowstone grizzly bears to changes in food resources: a synthesis. Report to the Interagency Grizzly Bear Committee and Yellowstone Ecosystem Subcommittee. Interagency Grizzly Bear Study Team, U.S. Geological Survey, Northern Rocky Mountain Science Center, Bozeman, Montana, USA.
Animated image showing grizzly bear range expansion in GYE: 1990-2022
Sequential estimates of occupied ranges for grizzly bears in the Greater Yellowstone Ecosystem during 1990–2022 (Dellinger et al. 2023). Range extents are based on methods described in Bjornlie et al. (2014).
Animated image showing grizzly bear range expansion in GYE: 1990-2018
Sequential estimates of occupied ranges for grizzly bears in the Greater Yellowstone Ecosystem during 1990–2018. Range extents are based on methods described in Bjornlie et al. (2014).
Sequential estimates of occupied ranges for grizzly bears in the Greater Yellowstone Ecosystem during 1990–2018. Range extents are based on methods described in Bjornlie et al. (2014).
Grizzly bear on a remote camera.
When looking for a place to set up a capture location, biologists look for existing bear sign such as scratches on trees and bear scat. Sometimes traps are set in areas that have no obvious bear sign to determine if indeed bears are present.
When looking for a place to set up a capture location, biologists look for existing bear sign such as scratches on trees and bear scat. Sometimes traps are set in areas that have no obvious bear sign to determine if indeed bears are present.
Biologists Collecting Biological Samples from Grizzly Bear
USGS biologists collecting biological information from a grizzly bear they have captured. Biologists collect hair samples for genetic analysis, weigh the bear, and gather numerous measurements of the body, such as the head, paws, claws, teeth, etc. Overall condition of the bear is assessed as well, including a body fat measurement.
USGS biologists collecting biological information from a grizzly bear they have captured. Biologists collect hair samples for genetic analysis, weigh the bear, and gather numerous measurements of the body, such as the head, paws, claws, teeth, etc. Overall condition of the bear is assessed as well, including a body fat measurement.
Science and Products
Informing Management Options for grizzly bears in a Changing Greater Yellowstone Ecosystem
Project Overview The iconic grizzly bear of the Greater Yellowstone Ecosystem has exhibited a remarkable recovery in response to concerted conservation actions implemented since its listing as threatened under the Endangered Species Act in 1975. However, information regarding the potential effects and timing of climate change in conjunction with increasing human recreation and development will be
The Effects of Climate Variability and Change on Human-Bear Interactions in North America
Negative human-bear interactions are a common problem and management priority for many wildlife agencies in North America. Bears are adaptable to anthropogenic activity and food sources which creates opportunities for conflict with humans, including property damage, livestock depredation, and in severe cases, human injury. Acute climate events and long-term directional climate change can exacerbat
Interagency Grizzly Bear Study Team
The Interagency Grizzly Bear Study Team (IGBST) is an interdisciplinary group of scientists and biologists responsible for long-term monitoring and research efforts on grizzly bears in the Greater Yellowstone Ecosystem (GYE). The team was formed by the Department of the Interior (DOI) in 1973 as a direct result of controversy surrounding the closure of open pit garbage dumps within Yellowstone...
NOROCK 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...
IGBST Grizzly Bear Food Synthesis Report
How to Cite: Interagency Grizzly Bear Study Team. 2013. Response of Yellowstone grizzly bears to changes in food resources: a synthesis. Report to the Interagency Grizzly Bear Committee and Yellowstone Ecosystem Subcommittee. Interagency Grizzly Bear Study Team, U.S. Geological Survey, Northern Rocky Mountain Science Center, Bozeman, Montana, USA.
Animated image showing grizzly bear range expansion in GYE: 1990-2022
Sequential estimates of occupied ranges for grizzly bears in the Greater Yellowstone Ecosystem during 1990–2022 (Dellinger et al. 2023). Range extents are based on methods described in Bjornlie et al. (2014).
Sequential estimates of occupied ranges for grizzly bears in the Greater Yellowstone Ecosystem during 1990–2022 (Dellinger et al. 2023). Range extents are based on methods described in Bjornlie et al. (2014).
Animated image showing grizzly bear range expansion in GYE: 1990-2018
Sequential estimates of occupied ranges for grizzly bears in the Greater Yellowstone Ecosystem during 1990–2018. Range extents are based on methods described in Bjornlie et al. (2014).
Sequential estimates of occupied ranges for grizzly bears in the Greater Yellowstone Ecosystem during 1990–2018. Range extents are based on methods described in Bjornlie et al. (2014).
Grizzly bear on a remote camera.
When looking for a place to set up a capture location, biologists look for existing bear sign such as scratches on trees and bear scat. Sometimes traps are set in areas that have no obvious bear sign to determine if indeed bears are present.
When looking for a place to set up a capture location, biologists look for existing bear sign such as scratches on trees and bear scat. Sometimes traps are set in areas that have no obvious bear sign to determine if indeed bears are present.
Biologists Collecting Biological Samples from Grizzly Bear
USGS biologists collecting biological information from a grizzly bear they have captured. Biologists collect hair samples for genetic analysis, weigh the bear, and gather numerous measurements of the body, such as the head, paws, claws, teeth, etc. Overall condition of the bear is assessed as well, including a body fat measurement.
USGS biologists collecting biological information from a grizzly bear they have captured. Biologists collect hair samples for genetic analysis, weigh the bear, and gather numerous measurements of the body, such as the head, paws, claws, teeth, etc. Overall condition of the bear is assessed as well, including a body fat measurement.