On November 22 I published a Facebook post asking for help in locating my remaining target species, to see if my fellow birders had good info. One spot recommended to me by Matthew Thompson was Lake Hiawatha Park, for Cackling Geese. Of course I know this place well, but it reinforced that I needed to get there to find the Cackling Geese that were lurking there within the large flock of Canada Geese.
Cackling Geese used to be considered the smallest four subspecies of Canada Geese. It is easy to see why, since they look almost identical to the larger subspecies! But then in 2004 the American Ornithologists' Union split off the Cackling Goose into its own separate species, and birders had to catch up and figure out how to distinguish among the two in the field. In my opinion, the distinguishing characteristics are a bit understudied. Perhaps this is just because of my perspective as a Minnesota birder - we have the most difficult ID problem here because we get the smallest Canada Geese and the largest Cackling Geese, but not a large number of these small geese - so the differences are not as obvious as you might get elsewhere, and it is harder to find examples to work with.
Sometimes doing a big year is a challenge in traveling a long way - biking out to a bird that is a long way from home. Other times, the challenge is getting a view of a secretive bird, or in looking for a species at just the right time. And at still other times, there is the ID challenge of picking out a cryptic bird species - one that looks extremely similar to another species. Cackling Goose is definitely this last type of challenge!
On November 23 I set out on my bike for Lake Hiawatha. I got there and headed out onto the golf course that is on the west side of the park. This area usually hosts large numbers of white-cheeked geese (that being the new term to refer to both Canada & Cackling Geese together) in the fall. This is good habitat for them due to the nice open water of Lake Hiawatha (which stays remarkably open despite its shallowness, perhaps because of the current from Minnehaha Creek, and perhaps because the golf course used to be a marsh, and so pumps a lot of water into the lake), next to lots and lots of short, grassy fields for the geese to forage on. There were some geese up on the golf course, but most were on the lake, so I headed to the shore. I walked along the area where the geese were and before long I noticed a couple of geese that stuck out for being much smaller than their neighbors. It would be very nice if this were enough to conclusively ID them as Cackling Geese, but there is enough variation in Canada Geese that a small Canada Goose can look pretty small next to a large one.
After finding a suitably small goose, you start to look for other field marks to confirm - a short bill; a short, thick-looking neck; a steep forehead; a flat-top to the head, giving it a blocky appearance; and a higher-pitched, squeakier call. I kept looking at these small geese and found that they did have a shorter bill, short necks, a steep forehead and a blocky head shape. I had found a couple of Cackling Geese! And they were pretty close, so I was able to get some good pics. I was really trying to get some good ones with the Cackling Goose right next to a Canada Goose so that it would show off the subtle differences!
With these three pictures you can see some of the key differences between Cackling and Canada. The first difference is how much smaller the Cackling Goose is - it is about 2/3 the size of a Canada, so when you see them side by side the size difference is striking. Two, the bill on the Cackling is shorter and, when viewed with the rest of the head, stubbier-looking. The bill of the Canada looks longer and more slender. Three, the head shape of the Cackling is blockier - with a steeper forehead rising from the bill and a flatter top to the head. The Canada has a more smoothly rounded head with a longer, more gradual slope up from the bill. Four, the neck of the Cackling is shorter, and thick-looking relative to the rest of the goose. The neck is a really hard field mark to photograph well because geese have an amazing ability to extend, retract, fluff up, and flatten their necks (all of which changes the appearance), so it is best to watch the appearance of the neck over time as the goose moves rather than in a single still shot. But you can still see here that the Cackling has a short, relatively thick neck.
As I was there, many of the geese started taking off and flying over to the golf course to feed. When geese take off, they often get very vocal, with lots of honking! When the group that included my Cackling Geese took off, I heard one voice that was much higher and squeakier than the rest, helping to confirm my ID of Cackling.
One more cool species for my big year!
Mile biked on this trip: 8.7
Miles biked during this time (since the last new bird species): 8.7
Miles biked year to date: 3,232.5
Species count (MN): 235
Species count (overall): 236
My bike birding eBird profile: https://ebird.org/profile/MTIxNDg5NQ (Please note that you need a free eBird account to see profiles in eBird)
Fundraising links for the two organizations I am supporting with this green big half year. These causes are really important and they could really use your dollars to do a lot of good!
Friends of Sax-Zim Bog: https://www.givemn.org/story/Greggseverson
National MS Society: http://main.nationalmssociety.org/goto/GreggSeverson