Endangered
Species Success Story
Aleutian Geese were one of the first on the new Endangered Species
List in
the 1970s 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 couldnt 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.
|
Future
Geese Counts Could Use Vertical Aerial Photography
This initial photographic test may be useful again when the Aleutian
Geese return in the spring. Farmers and ranchers are increasingly
concerned with the damage being done to property from the vast flocks
of birds feeding on crops and dairy pastures. Accurate bird population
counts will contribute to good management of wildlife along with
local concerns. By using high resolution aerial imagery, counts
could be done quickly and accurately using both photography and
computer image recognition methods.
Article and photographs copyright Gary Todoroff
Read
more about Crescent City's Aleutian Goose Festival ...
On-Scene
At the Aleutian Goose Festival (California Coast & Ocean: Vol.
18, No. 1, Spring 2002)
|