Mystery Goose

On December 29 we were walking around at the Gilbert Riparian Preserve when we heard a tremendous amount of honking coming from one of the ponds – a flock of Canada Geese was in residence. This is the right time of year to spot a Snow Goose or two mixed in here, so I scanned the flock, and sure enough…

031 (2)But is that a Snow Goose? (These photos were taken using the 200 mm lens I got for Christmas. The bird was pretty far out.)



There are two very similar-looking species of white goose in North America, the Snow Goose (the larger, more common one, which I’d seen before) and the Ross’s Goose (the smaller, less common one, which would be a new life bird for me). The usual way to tell them apart is by examining the head and bill. Ross’s Geese have rounder heads and shorter bills. Their bills have some bluish or greenish coloring around the base and typically don’t have the black “grin” that a Snow Goose’s bill does. To further complicate things, the two species hybridize pretty regularly. So what’s this one? I wasn’t sure, and since Ross’s Goose would be a lifer, I posted the (admittedly crappy) photos on Twitter and Facebook. On Facebook I directed my question to an old college birding buddy who’s now a PhD student in ornithology, while on Twitter I just posted a general plea for help, which led to someone there forwarding the photos to an ornithologist acquaintance of his own.

The bill coloration looks Ross-ish, but in that last photo the head shape and bill size look more Snow-ish. My Twitter follower and his ornithologist friend decided it might be a hybrid. My ornithologist buddy from college, on the other hand, declared that to be a cop-out and put his money on Ross’s Goose, albeit maybe one with a slightly bigger bill than normal. When I checked eBird and saw that someone else had reported a Ross’s Goose at the Gilbert Water Ranch the same day, I decided to call the bird in these photos my life Ross’s Goose.

Yes, birders really do spend their time thinking about and debating this sort of thing. Here are a Snow Goose and a Ross’s Goose so you can make your own comparison. What do you think?

Ross’s Goose (Wikimedia Commons photo by Dick Daniels)
Snow Goose (Wikimedia Commons Photo by Simon Pierre Barrette) – ignore the brownish coloring on the face, it’s not relevant to the ID

7 thoughts on “Mystery Goose”

  1. Based on the pictures (and only having seen Snow Geese myself), I’d probably guess Ross’s Goose, too — you’re right, though, that’s a tough call. Very cool either way! Also, very exciting about the new camera lens! I use a 200 mm lens, too, and I’m looking forward to seeing more pictures of the awesome creatures you see up north. :D

  2. Two points:
    First, my uneducated guess is a Snow Goose.
    Second, your last photo (from your Twitter plea) shows a Canada Goose staring straight at you, as if he knows he’s not your subject. Poor little guy.

    I hope I’m wrong, for your sake!

  3. For what it’s worth, one of my bird books mentions a Lesser Snow Goose. I am not an ornithologist, nor even do I consider myself a birder, yet I don’t want to burst your “lifer” bubble so I hope it is indeed a Ross.

  4. I know i’m well behind the times here, and being but a first year biology student my opinion isn’t even worth it’s weight in goose down, but looking repeatedly at your pictures and my Peterson guide along with Cornell Ornithological lab web page, i declare it Chen rossii, so three cheers for you!

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