Duck, Duck, Goose 

by Steve Frye  

In Kindergarten, I can remember playing 'Duck, Duck, Goose'. As you may recall, a group of kids sit in a circle and one child walks around the circle and pats everyone on the head saying 'Duck'. At some point the child will switch and pat someone on the head and say 'Goose'. Now everyone starts screaming and the child that was tagged 'Goose' runs after the tagger around all the children hoping to tag that child before they make it around the circle and sit down in the original 'Goose' child's spot. The game continues like this until everyone loses interest. Nowadays, birders play a similar game at the reservoirs. Everyone will stand around in a circle looking at the waterfowl. Then someone will start announcing 'Duck, Duck, Duck, Branta canadensis parvipes' and everyone runs around screaming. Soon they will settle down and the game starts all over again until everyone loses interest and goes home. 

Canada Goose

So just what is a Branta

canadensis parvipes? Branta canadensis is the scientific name for a Canada Goose and the parvipes is the subspecies denotation. Several years ago Canada Geese were 'split' into Canada Goose and cackling goose because evidence showed that these very similar

looking geese were, in fact, separate populations and genetically different

enough to be considered different species. Within these species there are subspecies which further distinguish the population.  You may want to think of these as races within a species. For example, in humans most

Scandinavians have certain physical features and most Central Americans have other characteristic features, but both of these groups are human. Different-- but the same, if you will. So to with Canada Geese and cackling geese, Canada Geese have 7 major subspecies and cackling geese have 4 major subspecies. If you look carefully at a flock of Canada Geese flying overhead along the Front Range its apparent that they are not all alike. The overall sizes of the geese and neck lengths vary quite a bit. What you are seeing is different subspecies flying along in the same grouping. So how does one distinguish goose subspecies or even species? That is where it gets sticky.  

Aleutian Cackling Goose

The main distinction between cackling and

Canada is body size. Cackling geese are a smaller bodied bird which nests mainly in Alaska and its island chains and the Canada Goose is a larger bodied bird common throughout Canada and the United States. The subspecies determination for these species relies not only on body size, but also subtle differences in plumage, bill and head shape, neck length, and others characteristics. The smallest subspecies of the cackling goose, minima, is slightly larger than a mallard and the largest of the Canada Goose subspecies, maxima, is approaching the size of a tundra swan. In between these two extremes there exists a gradation of all the other subspecies.

How can you tell if they are really Canada Geese?  

© Tom Wilberding

It may seem that body size would be the easiest way to distinguish these species and subspecies. Certainly, is can be helpful in eliminating choices that are far off from the bird you are observing. However, your perception of body size can be altered depending on the birds' body position, if its swimming or standing, or if its facing you or going away from you, even if it is excited or relaxed. Males also average 3-8% larger than females (and you cannot easily distinguish between the sexes in the field). First winter birds of both sexes are smaller. Of course, variation exists within a subspecies due to factors like genetics and nutrition. Body size can be a very useful criterion in the field, but you need to base your identification on more than body size alone. 

Similar to body size is the length of the culmen (i.e. the bill), which can help distinguish these species and subspecies. The subspecies with the largest body sizes also have the largest culmen lengths. In fact, the graphs of body size and culmen length look almost identical for these subspecies. Unfortunately, the same pitfalls that befell our determinations of body size also apply to culmen length.  

Click here for a Chart for more of the Hints. 

[You can even print it, cut it out, and put it in your

field guide to refer to it in the field.]   

When you come upon a flock of Canada Geese, many birders glaze over and dismiss them as all the same, 'just Canada Geese'. The challenge of becoming a better birder is to look over the flock carefully, not only to see if there are some unique geese in the bunch like greater white-fronted or snow geese, but also to see if you can discern any cackling geese or subspecies. Take your time and scan the flock slowly. Often different subspecies will associate together forming a discreet group within the flock. Sometimes our observation skills are honed the keenest when we look at birds that are common and abundant like American Robins or Canada Geese.  

Canada Goose

Saturday Walk, but I have better uses for my 'birding time'. I will take a closer look at geese and try to differentiate subspecies. The subject of subspecies is interesting because you are watching evolution in progress. These groups are geographically separate from one another and they are responding to local environmental pressures. Through time, lots of time, these subspecies will differentiate further and become their own species. The task of telling these very similar birds apart is challenging, but as my kickboxing instructor says, 'when we do our best, our best gets better'. So take some time and observe closely.

If you have any questions, give the Wild Bird Center a call

303-442-1322.      

Sibley Guides: Distinguishing Cackling Goose & Canada Goose

Bill Schmoker Blog: Cackling & Canada Goose Photos 

Idaho Birds: Cackling Goose - Canada Goose Subspecies ID Indicators  

Cornell Lab of Ornithology, All About Birds: Canada Goose 

Cornell Lab of Ornithology, All About Birds:  Cackling Goose   

We recently added all our Saturday Morning Bird Walk sightings from the past five years to the ebird database. That's over 15,000 observations that are available to researchers and the general public! Ebird is a great way to keep track of your bird observations. The program organizes your data into state and county lists. You can easily analyze your data and add any notes or classifications to your data. It's very user friendly, but the big benefit is that researchers and other birders can also benefit from seeing your observations. Don't fear, you can also hide your data from public consumption if you wish. The other nice benefit is that your online list will always be available and you don't have to worry about upgrading programs or switching computers. Check out ebird and get started entering your observations.                      www.eBird.org

Goose 234 by Sarah Coursey  

If we took all of our goose mothers  

The blue-green earth we cherish not
Came from their golden egg
And yet we leave the common lot
In Autumn fields to beg  

But what of fine democracy
Of taking turns in flight?
One cuts the wind and points the V
And portions out the night  

When the cornfields turns to ice
She flies her secrets south
And whispers coyly 'silly goose'
Spread wide across my mouth

Tree Geese  

British folklore contends that geese eggs grew in trees cavities near water. Once hatched, the flightless young geese would pop out of the tree and fall into the water. This is why goose is grouped with fish and allowed to be eaten on Fridays as declared by Pope Innocent III (1160-1216). 

The Goose Tree