The goose on page 1 appears to be a hybrid Chen x Branta, referring to the genus Chen (probably Snow or Ross's) and genus Branta (probably Cackling or Canada). I received 6 comments from ID Frontiers listserve that suggest Snow Goose as one parent and Cackling or Canada Goose as the other parent. One comment suggested that this bird could be a second (or greater) generation hybrid. I believe that the short bill rules out Snow x Canada, as both have significantly larger bills. The size and shape of the bill is a perfect match for Richardson's Cackling Goose, suggesting that Cackling Goose is one of the parents (i.e. Snow x Cackling or Ross's x Cackling). Can Ross's x Canada be ruled out?

The dark brown body coloration, a feature not normally present in any plumage of Chen or Branta goose, is confusing. Also, the dark feathers on the vent are not a feature of either Snow or Ross's Goose among Chen species, nor any Branta species. "Melanism" may be the explanation. Chen x Branta hybrids apparently show some melanism or at least express dark phase Chen features (see pages 2-4).

I have added photos of 16 other apparent Chen x Branta hybrid geese. Several recent Colorado birds are on page 2. Three probable Ross's x Cackling Goose hybrids photographed by Bill Schmoker on pp 3-4 (for more discussion of these 3 birds from Boulder, Colorado, visit Bill's blog site at http://brdpics.blogspot.com/2009/02/faces-in-crowd.html). Additional Chen x Branta hybrids including a family group with 4 hybrid progeny from Colorado, 3 birds from Washington state (northwest USA) and another from the Netherlands have been added to p. 4.

This hybrid combination (Chen x Branta) is rarely discussed in cyberspace. Here are some electronic links I found on this topic:
http://elibrary.unm.edu/sora/Auk/v069n04/p0425-p0428.html
http://users.utu.fi/hlehto/photo/hybrid/
I presume there is more on this topic in the textbook literature (but maybe not).

The identities provided for the following photos are presumptive. Comments welcome. Click on any photo to enlarge.