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 http://www.flickr.com/photos/57791790@N00/289046358 under license http://creativecommons.org/licenses/by-nc/2.0/)

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, http://www.lafebervet.com )
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)

Tuesday, April 17, 2012

Calendar Birds

For arctic nesting Peregrine Falcons we know that late arrival at a breeding site does not entirely preclude a successful breeding season, but a shortened season stacks the odds against those that do arrive later.  Early arrival lengthens the season and may ensure easy access to a breeding territory, but the trade-off can be low food supplies.  Apart from resident lemmings (when present) and early season ground squirrels, Snow Buntings are often the only migrants species present when the falcons first arrive.

Male ground squirrels are among the first resident prey to appear in the spring
Snow Buntings are almost always the first migrant prey, often arriving ahead of peregrines (G.Court)
Under ideal conditions arrival would coincide with no competition for breeding sites, mild weather and plentiful food. To a degree, arrival depends on date of departure from wintering areas, which is prompted by, amongst other factors, day length.  Judgement with regard to when to leave can be very precise even over several years for some Calendar Birds.
 
A falcon known as Island Girl (see Falcon Research Group Blog) that winters in Chile and spends her summers on Baffin Island, Nunavut began her inward migration April 14, 2012.  Her departure date in each of the 4 migration years that she has been tracked has varied only slightly (12/04/2009, 13/04/2010 and 11/04/2011).  With no way to judge what can be highly variable environmental conditions thousands of miles to the north, tundra peregrines simply keep going until they encounter circumstances that preclude further travel.
Variability in snow cover near the Hudson Bay on or about departure day in years Island Girl has been tracked by FRG (green=snow free, blue=snow/ice, black=open water)
By late May snow cover around the Hudson Bay has retreated 300 miles further northward, in some years reaching almost as far as the Manitoba border with Nunavut.  Thousands of peregrines literally stream into the Arctic flying around or over the Hudson Bay at this time of year.
Differing routes taken by Island Girl 2009 - 2011
Chance encounters in the vast Canadian Arctic are extraordinary.  To get to our Baffin Island study site at Steensby Inlet our field crews usually usually fly from Rankin Inlet to Iqaluit, a route that overflies South Hampton Island and the Hudson Strait...a flight path remarkably similar to that taken by Island Girl in 2010.  
Island Girl's roost location (blue) June 2, 2010 (source http://www.frg.org/track_pefa12_2010n_archive.htm) and the approximate photo location (jet) also June 2, 2010



By 2010, we were already well aware of Island Girl's breeding location on south Baffin Island, and en route to Iqaluit, Mark Prostor snapped a shot of the Hudson Strait a little to the east of Salisbury Island and south of her breeding location on June 2.

Conditions in the the Hudson Strait June 2, 2010.  Edge of Salisbury Island can be seen middle right (M. Prostor)

You can follow daily location updates and the FRG crew as they literally chase "Island Girl" and "Felipe" (a satellite tagged male tundra peregrine) north from Chile.

Sunday, March 25, 2012

A fortnight away

For many bird species clutch size increases with latitude, yet throughout their range peregrines (migrants and residents alike) normally lay 4 eggs.

A clutch of 4 eggs is normal throughout peregrine range
Those that breed at relatively southern latitudes have the luxury of time (more than 200 days) and very mild breeding conditions, even to the point that a breeding season can be salvaged by laying a second clutch of eggs if the first is lost.

Typical phenology for migrant Peregrine Falcons in North America

Location Lat  Arrive Lay Hatch Fledging Migration Days
Colorado   39    Mar 10  Apr 10  May 14 Jun 22 Oct 20 224
Ontario 48   Apr 01  Apr 20  May 24 Jul 02 Oct 15 202
Alberta 53   Apr 15  May 05  Jun 08 Jul 17 Oct 05 173
Alaska 63   Apr 20  May 11  Jun 14 Jul 23 Sep 20 153
Nunavut 65   May 23  Jun 08  Jul 12 Aug 20 Sep 17 117

Not so for Arctic-nesting peregrines attempting to raise a brood to independence. The window of opportunity slams shut in a measly 120 days or so, and it's a one shot deal. From the perspective of a Hatch Year bird, the schedule is tight.  Research conducted by Alex Anctil shows a nestling with the best chances of survival will come from the first or second laid egg in an early laid clutch.
Early hatched (July 9), 1 day old nestling, eyes still shut and egg tooth visible
 Almost 3/4 of a nestling's "life" is taken up by incubation (~34 days) and growing time on the nest ledge (~40 days), leaving only 28 days to figure out how to fly and catch at least some prey before their first unknown outward migration begins.

Almost hard-penned (A. Anctil)
For tundra peregrines, the relative ease (presumably) of wintering is close to over...departure for breeding cliffs is only a fortnight away.