Greg A Breed

Development of statistical Particle Filters for Movement Modeling and Analysis.

Collaborators: Joanna Mills-Flemming, Mike Dowd, Chris Field

Because many methods of fitting mechanistic CRW models to animal movement data are difficult and/or limiting (eg. WinBUGS or Kalman Filtering), we are developing flexible particle filter/smoother approaches for fitting these models with time-varying movement parameters. I have recently been successful in implementing models that fit regular location to irregular data and have implemented a smoother. So far I've found these approaches exquisitely sensitive to subtle changes in an animal's movement; changes usually missed by discrete switching state models.  This work is still ongoing and we expect to publish the model in 2011. 

    

Above: Time-varying parameter and location estimates fit using a particle smoother to a California sea lion tracked in 2007 by GPS.  Intensity of color indicates the movement parameter estimate at that time step, with brighter colors nearer 1 and darker colors near 0.  Note that the parameter estimates suggest a bi-phasic movement behavior for most of the track, but such biphasic movement need not be hard-coded a priori into movement models as in conventional state-switching models.

Modeling Movement of Sea lions in the Channel Islands with tides, currents, and waves

Collaborators: Dan Costa, Patrick Robinson, Joanna Mills-Flemming

Animals are motivated to move based on external and internal conditions, but may limit expensive movements such as migrations to periods when they are energetically cheapest. I am looking at how carefully sea lions time travel between foraging areas and rookeries to ocean and tidal current patterns. These currents can enhance habitat for prey species but can also increase or decrease metabolic costs of travel depending upon time and location.

Modeling Movement of California Sea Otters

Collaborators: Emily Golson (lead), Tim Tinker, Jim Harvey

This project is just getting underway (as of Spring 2011). I will add more as it develops.

FMAP - TOPP data synthesis project

Collaborators: Barb Block, Dan Costa, Ian Jonsen, Arliss Winship, Sal Jorgensen, Elliot Hazen and others

The Tagging of Pacific Pelagics (TOPP) program of the Census of Marine Life produced an enormous amount of tracking data collected from over 30 species in the Pacific ocean.  Synthesizing these data to highlight major patterns and important areas of the Pacific Ocean ("Hot Spots") from tracking data is the major goal.  This work will be published in Nature in the first half of 2011.

Quantitative movement analysis of TOPP bird and mammal dataset

Collaborators: Dan Costa, Sara Maxwell, Nikky Teutschel, Chandra Goetsch, Patrick Robinson, Kim Goetz

The TOPP synthesis project is broad in scope, but many nested and more species specific questions remain to be investigated. The TOPP group has collected a huge quantity of data, parts of which I analyzed during my post doctoral appointment at UC Santa Cruz. I also assessed methods for handling Argos error and investigated the roll of data quality on the ability to detect relevant behavioural signals, used state-space methods to relate elephant seal movement to oceanography and diving behaviour, and collaborated with students in the Costa lab group working on TOPP data.

State-space analysis of Sable Island grey seal movement foraging

Collaborators: W. Don Bowen, Ian Jonsen, Ransom Myers, Marty Leonard

This is my Ph.D. work and I am still producing papers and participating in work with my last trip to Sable Island being January 2011. An old but extensive description of the work may be found here.  A copy of my Ph.D. thesis is available on the publications page.

Quantification of grey seal movement with respect to ground fish wintering areas in the Gulf of Saint Lawrence.

Collaborators: Valerie Harvey, Hugues Benoit, Mike Hammil, Doug Swain

Using a variety of analytical methods, these projects are assessing the habitat use and behaviour of grey seals in areas of where winter aggregations of demersal fishes form. This is particularly relevant given the possible interaction between commercially important fisheries and grey seals.

Assessment of olive ridley sea turtle habitat use for marine protected area planning in Gabon, central Africa.

Collaborators: Sara Maxwell (lead), Dan Costa

Using tracking data, Sara is assessing habitat usage of olive ridely sea turtles in order to provide advice for the construction of marine protected areas off Gabon. This includes the expansion of a current MPA and the development of a politically challenging international MPA in Western Africa.

Impacts of Mississippi River nutrients on the Northern Gulf of Mexico.

Collaborators: George Jackson, Mike Dagg, Tammi Richardson

For my Master's at Texas A&M and for a year afterward as a research associate at the Louisiana Universities Marine Consortium, I analyzed and modeled plankton ecology of the Northern Gulf of Mexico, particularly the regions impacted by the Mississippi River effluent. This work involved a number of modeling and oceanographic surveys of the lower Mississippi River and norther Gulf of Mexico. Some time was also spent modeling the North Pacific in the Gulf of Alaska as part of GLOBEC. Much of this work is published and reprints may be found on the publications page.

Undergraduate research.

My undergraduate work involved a wide range of studies into the ecology and behavior of arthropods. I worked for Dr. David Andow and his students for most of my time at the University of Minnesota on a variety of insect systems. In addition, I spent a year at the University of Hawaii working on coral reef crabs with Dr. John Stimpson, a summer at the University of Georgia Marine institute studying the foraging ecology of salt marsh crab with Dr. Steve Pennings, and a semester studying the circadian rhythms of fiddler crabs my last year at the University of Minnesota with Frank Barnwell.

Last update November 2011