My Wild Goose Chase

Or Vertical Aerial Photography and Computer Analysis to Determine Aleutian Geese Population

Endangered Species Success Story

Aleutian Geese were one of the first on the new Endangered Species List in the 1970’s with about 800 birds. Today, population estimates are over 70,000.

Geese typically roost in California offshore of Crescent City, in Arcata, and at the Humboldt Bay National Wildlife Refuge south of Eureka. During the day, they fly to surrounding fields and pasture land, feeding and fattening up for the long trip north to the Aleutian Islands in early spring.

The Humboldt Bay National Wildlife Refuge Complex contracted me to conduct an aerial photographic survey of the geese. Refuge Manager, Eric Nelson, and I designed a feasibility test to determine methods that would give a simple yet accurate way of counting the Aleutian Geese population with vertical aerial photographs.

Researchers band geese to track and get an understanding of migration patterns of the Aleutian goose. Bands can be found in almost any large flock. The number "35C" is specific to this one goose, photographed in the Arcata Bottoms off of Samoa Blvd, Arcata, California, March 2004.

An Aleutian is identified primarily by the white band around the base of the neck and the  white cheek patch. Until recently there were eleven sub-species of Canada Goose (Branta canadensis) and the Aleutian was included in this group. Now Aleutians have been split into the "Cackling Goose" group (Branta hutchinsii), which is their own specific species. The scientific name for the Aleutian Cackling Goose is Branta hutchinsii leucopareia .

Photograph courtesy Jeremy Todoroff

Coast Guard Helps Fellow Federal Agency

On March 20, 2003 the US Coast Guard, as a co-operative federal agency, flew us north in an HH65A helicopter using my vertical camera mount that has been used for thousands of other photographs with the Coast Guard, mostly for mapping surveys with other federal agencies. We had planned to fly a prescribed set of transects over Tolowa Dunes State Park where geese typically would feed (see map diagram). As with many plans, methods were changed and improvised once over the flocks.

At initial altitude of 1500 feet we couldn’t see any flocks, except some that were flying in response to the first appearance of the helicopter. Dropping down to 800’, individual birds were easy to spot. However, it would take several photos to cover large flocks on the ground, and some flocks continued to take flight as we flew over them. Climbing to higher altitudes, the geese became accustomed to us, and our eyes became accustomed to the visual signature of far-away Aleutian Geese. At 1400’ we could now identify geese on the ground and the geese recognized that we meant them no harm.

Test Photo Shows Feasibility of Counting with Vertical Photos

One photograph was selected for testing methods to count geese on the computer. Film from the Hasselblad aerial camera has a size of 56 x 56 mm (about 2.25 inches on a side) and was high-resolution scanned to a 120-megabyte digital photo file. The first photo shows the whole image, and the following captions describe how the count was done.

From the helicopter at 1400 feet altitude, Aleutian Geese on the ground were just visible with the naked eye. The red box represents the enlargement in the next images.

From the helicopter at 1400 feet altitude, Aleutian Geese on the ground were just visible with the naked eye. The red box represents the enlargement in the next images.


The photo interpreter uses the computer to “paint” dots over the geese in the enlarged area of the digital image.

Inset: By displaying just the dots in a software layer, geese can later be counted by manually adding up the dots. A simple software program could be used to count the dots, too. Eventually, a computer recognition application could be capable of identifying and marking the geese in the digitized vertical photograph.

Initial plans called for three overlapping flight lines to take vertical photographs of geese flocks north of Crescent City, California. However, it worked out better for testing to try different altitudes and just photograph a selected flock on the ground.

The US Coast Guard HH65A Dolphin helicopter contributed the aerial photo platform for the geese study. Three HH65 helicopters are stationed at Group Humboldt Bay McKinleyville Air Station with the one shown here flying past Trinidad Head and the rocky shores of North Coast California.

When not patrolling the rugged and often dangerous California North Coast, flight crews do some of their training by providing co-operative flights to federal agencies, such as the U.S. Fish and Wildlife Service.

Photo by Gary Todoroff,

Coast Guard Art Program

See more Coast Guard photos in the North Coast Photos stock database


Articles and photographs copyright Gary Todoroff. For licensed use, call (707) 445-8425 or contact him by email.