Biometrics Research

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The Biometrics Research Program addresses unresolved issues in sampling wildlife and habitats, designing ecological experiments, estimating biological and ecological parameters, testing biological and ecological hypotheses, and modeling population, community and ecosystem dynamics. The focus is on questions of immediate and ongoing concern to the Department of the Interior (DOI) and regional and international partners that either cannot be answered with existing quantitative techniques or that require exceptionally complex analytical approaches.

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Estimating demographic rates and abundance with emerging methods and multiple data types

Poisson distribution animation

"The Happy Biometrician"
(Credit: Mark Udevitz, USGS)

This research addresses the development and evaluation of theory and methods for using age-structure data, capture-mark-recapture data and other forms of supplemental data to make inferences about demographic rates.  Recent work under this theme includes evaluation of recently developed survival rate estimators based on standing age structure data that relax the often used but often unrealistic stable age structure assumption, and integrated population modeling to estimate demographic rates using four data types, sparsely scattered over a four-decade timespan.  Current projects include developing explicit maximum likelihood estimators that combine capture-mark-recapture data with other data types, as well as close kin mark recapture estimators.  



Forecasting Pacific walrus responses to human disturbance and environmental change

A satellite tagged Pacific walrus on a piece of sea ice

A satellite tagged Pacific walrus on a piece of sea ice.
(Credit: Tyrone Donnelly, USGS. Public domain.)

The Pacific walrus is a benthic feeding, ice-associated pinniped that ranges over the continental shelves of the Bering and Chukchi seas.  The extent of summer sea ice in the Chukchi Sea has decreased substantially in recent years and this trend is projected to continue.  Changes in the distribution of seasonal sea ice, and probable ensuing increases in ship activity and industrial development will likely affect walrus distribution and behavior and could affect the status of this population.  Department of Interior agencies need information on likely responses of walruses to disturbance and environmental change as a basis for management of this trust species.  Furthermore, the difficulty of studying this species requires a particularly comprehensive approach to forecasting its status under different environmental and disturbance scenarios.  Recent work under this Changing Arctic Ecosystems project includes possible consequences of calf mortality at land-based haulouts, and integrated behavior and bioenergetic models that provide mechanistic linkages between forecasted sea ice changes and potential population level consequences.  Current work focuses on effects of disturbance, as well as sea ice loss.