Monday, November 29, 2010

The Cackling Goose quandary

Cackling Geese are somewhat sought-after in these parts, being relatively rare and a very small proportion of the often massive Canada Goose flocks that dominate inland ponds and lakes. There are big wintering flocks around the Princeton-ish NJ area. This is rather different from e.g. the Katy Prairie area of TX where Canada/Cackling are in the distinct minority amongst other geese.

On Thanksgiving morning I headed out to Etra Lake, south-east of Hightstown in search of both Greater White-fronted and Cackling Geese, and found one of the latter but no GWF.

Picking out Cackling from Canada requires a certain comfort with the variation within Canada, which can be quite considerable within a flock. In particular the cheek patch and breast color are rather variable. Cackling is sometimes hyped as being a grayer-frostier colored bird, especially on the back, but there's quite a range of variation just within Canada. When I finally found the Cackling - identified by square head structure, bill size and small size - it was a similar color as a Canada next to it and well within the range of color variation of the flock. In fact I had one bird pegged as a Cackling by color until it raised its head and proved me obviously wrong.

In this mix there's also the big question of Lesser Canada Goose, which shares many of the attributes of Richardson's Cackling Goose and the separation of which is a potential nightmare. At the moment I'm (mostly) sweeping that under the rug but there have been some "Cackling" Geese that have certainly got me to wondering, in particular last winter's Rahway River Park birds.

A recent post by Sibley on Cackling vs Canada goose bill structure is pertinent here. The whole ID morass is still being worked out. While that effort is ongoing I rather suspect that Cackling Goose in eastern NY and NJ is really a bit bucket for all sorts of small outlier White-cheeked Geese. Which is why I still seek out reliable locations to study them further.

1 comment:

Springman said...

Wonderful shots!
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Springman!