Saturday, June 23, 2012

What?? F.p. anatundrium and F.p. tundriassini??

Of course there's no such thing as F.p. anatundrium or F.p. tundriassini, but for a little fun and to emphasize variation in plumage within sub-species even at small scales, I thought I'd post some images of 2 birds that were trapped one after the other at our study area in Rankin Inlet this spring, and assign an "invented" sub-specific name to them based on appearance and breeding range.

But first, a little context and an ever-so-brief introduction to the three sub-species of Peregrine Falcon that are recognized in North America...F.p anatum breeds south of the treeline throughout much of continental North America; F.p. pealei breeds in the Pacific Northwest from Puget Sound northward to Aleutian Islands in the Gulf of Alaska; and F.p. tundrius breeds in the North American Arctic and Greenland.  All have been studied sufficiently to generally distinguish one sub-species from the other at the population level.

North American sub-species (Source under license

A fourth sub-species (F.p. cassini) is a South American resident with variation in plumage that is known to include a color phase referred to as the Pallid Falcon. F.p. cassini is usually cited as the only subspecies of peregrine falcon worldwide that presents a white or pallid color morph.

Patagonian Pallid  F.p. cassini (Photo: Miguel Saggese, )
Our study area at Rankin Inlet on the western shores of the Hudson Bay in Canadian sub-Arctic is 500km north of the tree-line, and the peregrines that breed there are obviously well within the range of tundrius.  Notwithstanding the work that has been done to describe tundra peregrines, variation in plumage is so wide that assigning individuals according to the general rules that describe the sub-species in general is often difficult to do.

The two females in question expressed plumage characteristics so unlike that described for tundrius that if they had been caught during migration or on the wintering grounds would almost certainly not be to assigned to tundrius...thus our tongue-in-cheek "discovery" of two new sub-species that we named F.p. anatundrium and F.p. tundriassini.
Front view of our so called F.p. tundrassini (Photo M. Prostor)
Back and head of the same bird (Photo M. Prostor)
Our tundriassini along side the male with which  she was paired (Photo M. Prostor)
...and another of the pair (Photo M. Prostor)

The next female trapped was well marked with a salmon colored breast normally associated with F.p.anatum.  Although we were unable to compare the 2 females in the field, the images of each one when placed side by side nicely illustrate plumage variation, and underline just how difficult it can be to assign any given individual to is true sub-specific origin.  

 Same sub-species? Different sub-species? For fun we named them  F.p. anatundrium (L) and F.p. tundrassini (R)