Humboldt Bay Goose & Swan Study

Conservation Success Story: the Aleutian Cackling Goose

Goals include gathering data that will be useful to policy makers when addressing socio-political issues dealing with the geese in the Arcata area. There are several study objectives.

  • assess habitat preferences and diet in all seasons
  • determine habitat characteristics of roosts, nests and brood-rearing sites
  • determine energy budget in relation to disturbance (natural and human mediated)
  • determine carrying capacity of habitats
  • assess response of goose and swn plant-foods to grazing and fertilizing from goose droppings
  • determine fate of broods & lifetime reproduction of marked birds
  • determine movement of marked individuals throughout range

Goose Data Entry

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The Humboldt Waterfowl Research Group addresses questions dealing with traditional use of sites, mate choice, divorce, pair bond tenacity, extra-pair behavior, adoption and parental care.

There are 2 species of geese that make use of Humboldt Bay during their migration: Aleutian Cackling Geese (Branta hutchinsii leucopareia), and Black Brant (Branta bernicla). These geese nest in Alaska and winter with us in California. Numbers in these populations are approaching 100,000. Whereas the Black Brant stimulate new growth in their food in the bay (Zostera), Aleutians compete for limited pasture grass with local livestock. Look for blue neck collars on the Aleutians and smaller leg bands on the Brant.

A third species nests in the marshes and farmland around the bay: Western Canada Geese (Branta canadensis moffitti). Members of this ”resident“ flock have been recovered as far north as British Columbia and Alberta, but most return and spend their time right around the bay. This population fluctuates between 1,000 – 3,500 individuals. Look for and report big black neck collars on Western Canadas.

A small flock of Tundra Swans (Cygnus columbianus) has made use of the Eel River estuary and South Humboldt Bay each winter for many years. The flock is part of the Pacific Flyway population of swans. Students have the opportunity to observe and hear the Triumph Ceremonies of  these magnificent birds at Centerville, near Ferndale, and the Humboldt Bay National Wildlife Refuge.


Griggs KM & Black JM 2017. Allocation of parental care by Western Canada Geese Branta canadensis moffittiWildfowl 67, 44-59.

Cocke J, Alton S & Black JM 2016. Observations of Aleutian Cackling Geese (Branta hutchinsii leucopareia) breeding on Buldir Island, Alaska: forty-seven years after the rediscovery of a remnant population. Wildfowl 66:113–126.

Spragans KA, Black JM & Johnson M 2015. Aleutian Cackling Goose Branta hutchinsii leucopareia use of pastures in relation to livestock management. Wildfowl 65, 31-50.

Mini AE, Bachman D, Cocke J, Griggs K, Spragens K & Black JM 2011. Aleutian goose recovery: a 10-year review and future prospectus. Wildfowl 61, 3-29.

Black JM, Gress C, Byers J, Jennings E & Ely C 2010. Behaviour of wintering tundra swans Cygnus columbianus columbianus at the Eel River delta and Humboldt Bay, California, USA. Wildfowl 60, 38-51.

Mini A & Black JM 2009. Expensive traditions: energy expenditure of Aleutian geese in traditional and recently colonized habitats. Journal of Wildlife Management 73, 385-391.

Black JM,Springer P, Nelson ET, Griggs KM, Taylor T, Thompson ZD, Maguire A & JacobsJ 2004. Site selection and foraging behavior of Aleutian Canada geese in anewly colonized spring staging area. Page 106-113 in T. J. Moser, K. C.VerCauteren, R. D. Lien, K. F. Abraham, D. E. Andersen, J. G. Bruggink, J. M.Coluccy, D. A. Graber, J. Leafloor, D. R. Luukkonen, and R. E. Trost, editors. Proceedings of the 2003 International Canada Goose Symposium, Madison, Wisconsin, USA.

Griggs KM & Black JM 2004. Assessment of a western Canada goose translocation: Landscape use, movement patterns and population viability. Page 214-222 in T. J. Moser, K. C. VerCauteren, R. D. Lien, K. F. Abraham, D. E. Andersen, J. G. Bruggink, J. M. Coluccy, D. A. Graber, J. Leafloor, D. R. Luukkonen, and R. E. Trost, editors. Proceedings of the 2003 International Canada Goose Symposium, Madison, Wisconsin, USA.

Information for Students

Students will be encouraged to record the location of foraging flocks and individually marked geese. In particular, participation will be expected from students in Waterfowl 420, Wildlife Techniques 311, and Wildlife Ethology 475.

  • Find out how to contribute to the study - Go to WCG resightings
  • Make use of the Waterfowl identification - study session

  • Fat scores - You may attribute a field index to each bird by determining the fatness of the abdomen. Make sure the bird is parallel to the observer and check whether it is 0=concaved/thin, 1=straight, 2=convex, 3=rounded, 4=well rounded/bulging. With practice, you may see that some fat scores fall between two index-points, so a score of 0.5, 1.5, 2.5, or 3.5 may be more appropriate.