Greg Wann is a Research Ecologist at the Fort Collins Science Center, who works primarily on conservation issues in the sagebrush and alpine biomes of western North America.
Greg Wann is a research ecologist with the U.S. Geological Survey (USGS) at the Fort Collins Science Center. He works primarily on conservation issues in the sagebrush and alpine biomes of western North America. Recent research projects include identifying priority habitats promoting greater sage-grouse persistence and assessing the population viability of white-tailed ptarmigan along Colorado’s Front Range. Greg completed postdoctoral training at the University of Georgia and Western Ecological Research Center (USGS) prior to joining the Fort Collins Science Center, where he worked primarily on applied conservation issues in upland gamebird ecology and management.
Professional Experience
2020 – present; Post-Doctoral Research Ecologist, USGS-FORT
2018-2020; Postdoc, University of Georgia, Athens, GA
2017-2018; Postdoc, Western Ecological Research Center, Dixon, CA
Education and Certifications
Ph.D., Ecology, Colorado State University
M.S., Ecology, Colorado State University
B.S., Biology, University of Missouri
Science and Products
Creating range-wide predictive maps of Greater Sage-Grouse seasonal habitats
Understanding Population Trends for the Gunnison Sage-Grouse to Inform Adaptive Management
Informing the Habitat Assessment Framework Process—An Assessment to Understand Habitat Patch Composition and Configuration Requirements for Range-Wide Sage-Grouse Persistence
Hierarchical Sage-Grouse Population Assessment Tool: Building a Foundation for True Adaptive Management
U.S. range-wide spatial prediction layers of lek persistence probabilities for greater sage-grouse
Simulation to evaluate response of population models to annual trends in detectability
A targeted annual warning system developed for the conservation of a sagebrush indicator species
A regionally varying habitat model to inform management for greater sage-grouse persistence across their range
Range-wide greater sage-grouse hierarchical monitoring framework—Implications for defining population boundaries, trend estimation, and a targeted annual warning system
Environmental gradients of selection for an alpine-obligate bird, the white-tailed ptarmigan (Lagopus leucura)
Estimating sightability of greater sage-grouse at leks using an aerial infrared system and N-mixture models
The importance of simulation assumptions when evaluating detectability in population models
Mismatches between breeding phenology and resource abundance of resident alpine ptarmigan negatively affect chick survival
Assessing lek attendance of male greater sage‐grouse using fine‐resolution GPS data: Implications for population monitoring of lek mating grouse
Hierarchical population monitoring of greater sage-grouse (Centrocercus urophasianus) in Nevada and California—Identifying populations for management at the appropriate spatial scale
Effects of seasonal weather on breeding phenology and reproductive success of alpine ptarmigan in Colorado
Estimates of annual survival, growth, and recruitment of a white-tailed ptarmigan population in Colorado over 43 years
Science and Products
- Science
Creating range-wide predictive maps of Greater Sage-Grouse seasonal habitats
Through a collaborative effort with multiple state and federal agencies, university researchers, and individual stakeholders, we are producing a set of predictive seasonal habitat maps for greater sage-grouse (Centrocercus urophasianus) spanning the entirety of the species’ U.S. distribution. This is the largest habitat modeling effort of its kind for the species and uses a large, compiled spatial...Understanding Population Trends for the Gunnison Sage-Grouse to Inform Adaptive Management
In partnership with the Bureau of Land Management and Colorado Parks and Wildlife, scientists from USGS Fort Collins Science Center and Western Ecological Research Center are applying a hierarchical monitoring framework to Gunnison sage-grouse (Centrocercus minimus) to evaluate population trends and inform adaptive management.Informing the Habitat Assessment Framework Process—An Assessment to Understand Habitat Patch Composition and Configuration Requirements for Range-Wide Sage-Grouse Persistence
USGS scientists are developing multiple products to directly inform the Bureau of Land Management's Sage-grouse Habitat Assessment Framework process.Hierarchical Sage-Grouse Population Assessment Tool: Building a Foundation for True Adaptive Management
USGS scientists and colleagues have designed a hierarchical monitoring framework for greater sage-grouse in Nevada, Wyoming, and northeastern California that will provide land managers with a monitoring and detection system to identify sage-grouse breeding locations (known as leks), clusters of leks, and populations where intervention may be necessary to sustain populations and to evaluate... - Data
U.S. range-wide spatial prediction layers of lek persistence probabilities for greater sage-grouse
This dataset contains two predictive lek (breeding site) persistence raster layers covering the U.S. greater sage-grouse distribution. In the United States, locations where males display and breed with females (i.e., leks) are often monitored annually by state wildlife agencies, providing valuable information on the persistence of birds in the surrounding areas. A U.S. range-wide lek database wasSimulation to evaluate response of population models to annual trends in detectability
In 'Simulation to evaluate response of population models to annual trends in detectability', we provide data and R code necessary to create simulation scenarios and estimate trends with different population models (Monroe et al. 2019). Literature cited: Monroe, A. P., G. T. Wann, C. L. Aldridge, and P. S. Coates. 2019. The importance of simulation assumptions when evaluating detectability in p - Publications
A targeted annual warning system developed for the conservation of a sagebrush indicator species
A fundamental goal of population ecologists is to identify drivers responsible for temporal variation in abundance. Understanding whether variation is associated with environmental stochasticity or anthropogenic disturbances, which are more amenable to management action, is crucial yet difficult to achieve. Here, we present a hierarchical monitoring framework that models rates of change in abundanAuthorsBrian G. Prochazka, Peter S. Coates, Michael O'Donnell, David R. Edmunds, Adrian P. Monroe, Mark A. Ricca, Gregory T. Wann, Steve E. Hanser, Lief A. Wiechman, Kevin E. Doherty, Michael P. Chenaille, Cameron L. AldridgeA regionally varying habitat model to inform management for greater sage-grouse persistence across their range
Identifying habitat needs for species with large distributions is challenging because species-habitat associations may vary across scales and regions (spatial nonstationarity). Furthermore, management efforts often cross jurisdictional boundaries, complicating the development of cohesive conservation strategies among management entities. The greater sage-grouse (Centrocercus urophasianus) is a rapAuthorsGregory T. Wann, Nathan D. Van Schmidt, Jessica E. Shyvers, Bryan C. Tarbox, Megan M. McLachlan, Michael O'Donnell, Anthony J Titolo, Peter S. Coates, David R. Edmunds, Julie A. Heinrichs, Adrian P. Monroe, Cameron L. AldridgeRange-wide greater sage-grouse hierarchical monitoring framework—Implications for defining population boundaries, trend estimation, and a targeted annual warning system
Incorporating spatial and temporal scales into greater sage-grouse (Centrocercus urophasianus) population monitoring strategies is challenging and rarely implemented. Sage-grouse populations experience fluctuations in abundance that lead to temporal oscillations, making trend estimation difficult. Accounting for stochasticity is critical to reliably estimate population trends and investigate variaAuthorsPeter S. Coates, Brian G. Prochazka, Michael S. O'Donnell, Cameron L. Aldridge, David R. Edmunds, Adrian P. Monroe, Mark A. Ricca, Gregory T. Wann, Steve E. Hanser, Lief A. Wiechman, Michael P. ChenailleEnvironmental gradients of selection for an alpine-obligate bird, the white-tailed ptarmigan (Lagopus leucura)
The warming climate will expose alpine species adapted to a highly seasonal, harsh environment to novel environmental conditions. A species can shift their distribution, acclimate, or adapt in response to a new climate. Alpine species have little suitable habitat to shift their distribution, and the limits of acclimation will likely be tested by climate change in the long-term. Adaptive genetic vaAuthorsShawna J Zimmerman, Cameron L. Aldridge, Kathryn M. Langin, Gregory T Wann, Robert S. Cornman, Sara J. Oyler-McCanceEstimating sightability of greater sage-grouse at leks using an aerial infrared system and N-mixture models
Counts of grouse present at leks (breeding grounds) during spring are widely used to monitor population numbers and assess trends. However, only a proportion of birds available to count are detected resulting in a biased population index. We designed a study using an aerial integrated infrared imaging system (AIRIS) and experimental pseudo-leks to quantify sightability (proportion of birds detecteAuthorsPeter S. Coates, Gregory T. Wann, Gifford L. Gillette, Mark A. Ricca, Brian G. Prochazka, John P. Severson, Katie M. Andrle, Shawn P. Espinosa, Michael L. Casazza, David J. DelehantyThe importance of simulation assumptions when evaluating detectability in population models
Population monitoring is important for investigating a variety of ecological questions, and N-mixture models are increasingly used to model population size (N) and trends (lambda) while estimating detectability (p) from repeated counts within primary periods (when populations are closed to changes). Extending these models to dynamic processes with serial dependence across primary periods may relaxAuthorsAdrian P. Monroe, Gregory T. Wann, Cameron L. Aldridge, Peter S. CoatesMismatches between breeding phenology and resource abundance of resident alpine ptarmigan negatively affect chick survival
1. Phenological mismatches – defined here as the difference in reproductive timing of an individual relative to the availability of its food resources – occur in many avian species. Mistiming breeding activities in environments with constrained breeding windows may have severe fitness costs due to reduced opportunities for repeated breeding attempts. Therefore, species occurring in alpine environmAuthorsGregory T Wann, Cameron L. Aldridge, Amy E Seglund, Sara J. Oyler-McCance, Boris C. Kondratieff, Clait E. BraunAssessing lek attendance of male greater sage‐grouse using fine‐resolution GPS data: Implications for population monitoring of lek mating grouse
Counts of males displaying on breeding grounds are the primary management tool used to assess population trends in lekking grouse species. Despite the importance of male lek attendance (i.e., proportion of males on leks available for detection) influencing lek counts, patterns of within season and between season variability in attendance rates are not well understood. We used high‐frequency globalAuthorsGregory T. Wann, Peter S. Coates, Brian G. Prochazka, John P. Severson, Adrian P. Monroe, Cameron L. AldridgeHierarchical population monitoring of greater sage-grouse (Centrocercus urophasianus) in Nevada and California—Identifying populations for management at the appropriate spatial scale
Population ecologists have long recognized the importance of ecological scale in understanding processes that guide observed demographic patterns for wildlife species. However, directly incorporating spatial and temporal scale into monitoring strategies that detect whether trajectories are driven by local or regional factors is challenging and rarely implemented. Identifying the appropriate scaleAuthorsPeter S. Coates, Brian G. Prochazka, Mark A. Ricca, Gregory T. Wann, Cameron L. Aldridge, Steven E. Hanser, Kevin Doherty, Michael S. O'Donnell, David R. Edmunds, Shawn P. EspinosaEffects of seasonal weather on breeding phenology and reproductive success of alpine ptarmigan in Colorado
Animal populations occurring at high elevations are often assumed to be in peril of extinctions or local extirpations due to elevational-dispersal limitations and thermoregulatory constraints as habitats change and warm. However, long-term monitoring of high-elevation populations is uncommon relative to those occurring at lower elevations, and evidence supporting this assumption is limited. We anaAuthorsGregory T. Wann, Cameron L. Aldridge, Clait E. BraunEstimates of annual survival, growth, and recruitment of a white-tailed ptarmigan population in Colorado over 43 years
Long-term datasets for high-elevation species are rare, and considerable uncertainty exists in understanding how high-elevation populations have responded to recent climate warming. We present estimates of demographic vital rates from a 43-year population study of white-tailed ptarmigan (Lagopus leucura), a species endemic to alpine habitats in western North America. We used capture-recapture modeAuthorsGregory T. Wann, Cameron L. Aldridge, Clait E. Braun