Jeffrey Bromaghin, Ph.D.

Science and Products

• Science
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  January 21, 2020

  Ecosystems Analytics

  Ecosystems Analytics is a group of quantitative biologists and research statisticians with a diverse range of expertise and experience (summarized below). We collaborate with internal and external partners to answer challenging ecological questions that are a high priority of the U.S. Geological Survey Alaska Science Center, sister agencies within the Department of the Interior (DOI), and various...

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  Alaska Science Center

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  January 21, 2020

  Ecosystems Analytics

  Ecosystems Analytics is a group of quantitative biologists and research statisticians with a diverse range of expertise and experience (summarized below). We collaborate with internal and external partners to answer challenging ecological questions that are a high priority of the U.S. Geological Survey Alaska Science Center, sister agencies within the Department of the Interior (DOI), and various...

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  December 15, 2017

  Polar Bear Population Dynamics

  Information on the status and trends of polar bear populations are needed to inform management of polar bears under US laws and international agreements. The USGS maintains a long-term research program focused on the population dynamics of the southern Beaufort Sea polar bear population. In addition, the USGS collaborates with the US Fish and Wildlife Service in population studies in the Chukchi...

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  Alaska Science Center

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  December 15, 2017

  Polar Bear Population Dynamics

  Information on the status and trends of polar bear populations are needed to inform management of polar bears under US laws and international agreements. The USGS maintains a long-term research program focused on the population dynamics of the southern Beaufort Sea polar bear population. In addition, the USGS collaborates with the US Fish and Wildlife Service in population studies in the Chukchi...

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• Data
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  June 28, 2020

  Multistate capture and search data from the southern Beaufort Sea polar bear population in Alaska, 2001-2016

  This data release contains two tables of information on polar bear distributions in the southern Beaufort Sea during spring, from 2001 to 2016. One table provides location (classified into 5 broad regions) of individual bears during the spring. The other table presents the aerial search effort by year and area.

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  Alaska Science Center

  October 17, 2016

  Fatty acid signature data of potential yellow-billed loon prey in the Arctic coastal plain of Alaska, 2009-2011

  This dataset contains fatty acid data expressed as mass percent of total fatty acids for several species potentially preyed upon by yellow-billed loons. These data were utilized in a quantitative fatty acid signature analysis to estimate the diet of yellow-billed loons nesting on the Arctic Coastal Plain of Alaska (Haynes et al. 2015).

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  Alaska Science Center

  March 16, 2015

  U.S. Geological Survey Polar Bear Mark-Recapture Records, Alaska Portion of the Southern Beaufort Sea, 2001-2010

  These data were collected by the U.S. Geological Survey, Alaska Science Center, Polar Bear Research Program as part of long-term on the southern Beaufort Sea polar bear population.

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  Alaska Science Center
• Publications
  Filter Total Items: 27

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  November 16, 2021

  Long-term variation in polar bear body condition and maternal investment relative to a changing environment

  In the Arctic, warming air and ocean temperatures have resulted in substantial changes to sea ice, which is primary habitat for polar bears (Ursus maritimus). Reductions in extent, duration, and thickness have altered sea ice dynamics, which influences the ability of polar bears to reliably access marine mammal prey. Because nutritional condition is closely linked to population vital rates, a prog

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  Ecosystems, Alaska Science Center

  September 23, 2021

  Survival and abundance of polar bears in Alaska’s Beaufort Sea, 2001–2016

  The Arctic Ocean is undergoing rapid transformation toward a seasonally ice-free ecosystem. As ice-adapted apex predators, polar bears (Ursus maritimus) are challenged to cope with ongoing habitat degradation and changes in their prey base driven by food-web response to climate warming. Knowledge of polar bear response to environmental change is necessary to understand ecosystem dynamics and infor

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  Ecosystems, Alaska Science Center

  June 11, 2021

  Diet composition and body condition of polar bears (Ursus maritimus) in relation to sea ice habitat in the Canadian High Arctic

  Polar bears (Ursus maritimus) rely on sea ice for hunting marine mammal prey. Declining sea ice conditions associated with climate warming have negatively affected polar bears, especially in the southern portion of their range. At higher latitudes, the transition from multi-year ice to thinner annual ice has been hypothesized to increase biological productivity and potentially improve polar bear f

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  Ecosystems, Alaska Science Center

  February 28, 2021

  Seal body condition and atmospheric circulation patterns influence polar bear body condition, recruitment, and feeding ecology in the Chukchi Sea

  Polar bears (Ursus maritimus) are experiencing loss of sea ice habitats used to access their marine mammal prey. Simultaneously, ocean warming is changing ecosystems that support marine mammal populations. The interactive effects of sea ice and prey are not well understood yet may explain spatial‐temporal variation in the response of polar bears to sea ice loss. Here, we examined the potential com

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  Ecosystems, Alaska Science Center

  October 1, 2020

  Analyses on subpopulation abundance and annual number of maternal dens for the U.S. Fish and Wildlife Service on polar bears (Ursus maritimus) in the southern Beaufort Sea, Alaska

  The long-term persistence of polar bears (Ursus maritimus) is threatened by sea-ice loss due to climate change, which is concurrently providing an opportunity in the Arctic for increased anthropogenic activities including natural resource extraction. Mitigating the risk of those activities, which can adversely affect the population dynamics of the southern Beaufort Sea (SBS) subpopulation, is an e

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  Ecosystems, Alaska Science Center

  September 8, 2020

  Drivers and consequences of apex predator diet composition in the Canadian Beaufort Sea

  Polar bears (Ursus maritimus) rely on annual sea ice as their primary habitat for hunting marine mammal prey. Given their long lifespan, wide geographic distribution, and position at the top of the Arctic marine food web, the diet composition of polar bears can provide insights into temporal and spatial ecosystem dynamics related to climate-mediated sea ice loss. Polar bears with the greatest ecol

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  Ecosystems, Alaska Science Center

  June 15, 2020

  Dietary fat concentrations influence fatty acid assimilation patterns in Atlantic pollock (Pollachius virens)

  A key aspect in the use of fatty acids (FA) to estimate predator diets using Quantitative FA Signature Analysis (QFASA) is the ability to account for FA assimilation through the use of calibration coefficients (CC). Here, we tested the assumption that CC are independent of dietary fat concentrations by feeding Atlantic pollock (Pollachius virens) three formulated diets with very similar FA proport

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  Ecosystems, Alaska Science Center

  November 20, 2018

  Energy-rich mesopelagic fishes revealed as a critical prey resource for a deep-diving predator using quantitative fatty acid signature analysis

  Understanding the diet of deep-diving predators can provide essential insight to the trophic structure of the mesopelagic ecosystem. Comprehensive population-level diet estimates are exceptionally difficult to obtain for elusive marine predators due to the logistical challenges involved in observing their feeding behavior and collecting samples for traditional stomach content or fecal analyses. We

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  Ecosystems, Alaska Science Center

  September 11, 2017

  QFASAR: Quantitative fatty acid signature analysis with R

  Knowledge of predator diets provides essential insights into their ecology, yet diet estimation is challenging and remains an active area of research.Quantitative fatty acid signature analysis (QFASA) is a popular method of estimating diet composition that continues to be investigated and extended. However, software to implement QFASA has only recently become publicly available.I summarize a new R

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  Ecosystems, Alaska Science Center

  August 30, 2017

  Simultaneous estimation of diet composition and calibration coefficients with fatty acid signature data

  Knowledge of animal diets provides essential insights into their life history and ecology, although diet estimation is challenging and remains an active area of research. Quantitative fatty acid signature analysis (QFASA) has become a popular method of estimating diet composition, especially for marine species. A primary assumption of QFASA is that constants called calibration coefficients, which

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  Ecosystems, Alaska Science Center

  July 26, 2017

  Detect and exploit hidden structure in fatty acid signature data

  Estimates of predator diet composition are essential to our understanding of their ecology. Although several methods of estimating diet are practiced, methods based on biomarkers have become increasingly common. Quantitative fatty acid signature analysis (QFASA) is a popular method that continues to be refined and extended. Quantitative fatty acid signature analysis is based on differences in the

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  Ecosystems, Alaska Science Center

  May 16, 2017

  Habitat degradation affects the summer activity of polar bears

  Understanding behavioral responses of species to environmental change is critical to forecasting population-level effects. Although climate change is significantly impacting species’ distributions, few studies have examined associated changes in behavior. Polar bear (Ursus maritimus) subpopulations have varied in their near-term responses to sea ice decline. We examined behavioral responses of two

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  Ecosystems, Alaska Science Center
• Software
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  June 20, 2017

  Model selection in Cormack-Jolly-Seber mark-recapture investigations

  Cormack-Jolly-Seber (CJS) mark-recapture models are widely utilized in ecology, providing estimates of vital rates and abundance that are difficult to obtain using other means.

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  Alaska Science Center

  June 20, 2017

  QFASA robustness to assumption violations

  Quantitative fatty acid signature analysis (QFASA; Iverson et al. 2004) has become a common method of estimating diet composition, especially for marine mammals, but the performance of the method has received limited investigation.

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  Alaska Science Center

  January 10, 2017

  Quantitative Fatty Acid Signature Analysis in R (qfasar)

  Quantitative fatty acid signature analysis (QFASA) is a method of diet estimation introduced over a decade ago (Iverson et al. 2004). 

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  Alaska Science Center