Thursday, February 14, 2013

Ross's Goose and Northern Harrier

[Bosque del Apache, NM. Feb., 2013]

At this time of year, there are over 47,000 Snow Geese at Bosque del Apache -- and, among these teeming thousands are also a few of the rarer Ross's Goose.


This tiny goose (the smallest goose species in the world) breeds at select sites in the Arctic Circle such as the Queen Maud Gulf Sanctuary. When seen with thousands of the larger snow geese, it can prove quite challenging to the casual observer to disambiguate between the two.
Snow Goose.

The Snow Goose and Ross's Goose are superficially quite similar: both are white geese with red bills and legs, black wingtips and textured necks.
However, when both species of geese are seen together [see photo above], the differences between them become a little more discernibly apparent:
  • The Ross's is smaller (i.e., it's about the same size as a mallard); and has a shorter neck
  • The Snow Goose bill displays pronounced "black lips" [see next photograph]
  • The junction between cheek and bill is curved (Snow) vs. straight (Ross's)

Snow Goose showing the "grinning patch"
Compare this to the Ross's profile:

Ross's Goose profile

The profile shots help highlight the differences discussed. The geese are  otherwise similar in their natural history and dietary habits. Both geese are also record defecators; a consequence of their high-fiber diets consisting of all kinds of grasses and other vegetable matter which they find in abundance in meadows and agricultural fields. This is a factor behind their current abundance and  thankful steady increase in population.

Moving on to a non-vegetarian bird, the Northern or Hen Harrier. This global raptor is found in North America and Northern Eurasia. The American race of the Harrier is a separate subspecies and is distinguished by its darker color.
Northern Harrier (female)

The Northern Harrier is one of the few hawks that is strongly sexually dimorphic -- the male is a spectacular grey while the female is brown and rufous. Not usually seen on the ground, a Northern Harrier was seen landing in the grass for a few brief moments before taking off.

Finally, no visit to the Bosque would be complete without a mention of the 8,000 Sandhill Cranes that were present:

A diminutive white goose, a beautiful hawk with a striking facial disc, and a stately crane in a pristine wilderness offer a glimpse of a wild America that we must preserve for future generations.

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