Wednesday, August 30, 2006

Goose confusion...

When I lived in Fort Collins, I paid a moderate amount of attention to the Canada Goose diversity, discovering like everyone else did that it is confusing. Now that the species has been split, it's a much bigger concern for the birding community as a whole. And I'm now even more confused, not so much about what I saw myself, but about what other people are reporting.

As I recall, the large majority of the small Canadas I saw looked to me like parvipes birds, the "Lesser Canada Goose." I saw only a small minority of birds that struck me as hutchinsii birds. Andrews and Righter reported that on a statewide basis, hutchinsii birds were "very rare."

Now comes the split, and I look at the most recent years' Colorado CBCs, and I see that about 1/3 of the "Canada" Geese are now being reported as Cackling Geese. This is similar to the proportion that used to be reported as "Canada Goose (small forms)" before the split. But but but but...

The parvipes birds, which seemed to me to constitute the greater part by far of the "small forms," were NOT split off as Cackling Geese! These are still considered Canada Geese. The subspecies that were split off as Cacklers had looked to me like only about 1% of the total birds, not 30%.

So this is what I am wondering now: was I wrong in my evaluation of the most common "small form" subspecies, or are Front Range birders now MASSIVELY overreporting Cackling Geese by including all these parvipes Canada Geese in the totals? What's the scoop from those out in the field there now? What do the specimens have to say?


Post a Comment

<< Home

Site Meter