[mou] Fwd: Boreal Birds - Updates

[Jim Williams]

Forward by Jim Williams, Wayzata, Minnesota

Please note that Jean Irons and Ron Pittaway, co-editors of the  
newsletter of the Ontario Field Ornithologists for the past 14 years,  
are retiring from that position. They have long made contributions  
that extended beyond the borders of Ontario.

JJW

Begin forwarded message:

From: Jean Iron <jeaniron at SYMPATICO.CA>
Date: November 21, 2007 9:15:12 PM CST
Subject: [BIRDCHAT] Boreal Birds - Ontario Updates
Reply-To: Jean Iron <jeaniron at SYMPATICO.CA>

Don Sutherland of the Ontario Ministry of Natural Resources (OMNR)  
tells me that the abundant meadow vole population last summer in the  
Hudson Bay Lowlands has almost certainly crashed. OMNR biologists did  
not see meadow voles in October and early November in areas where  
they were abundant in August. Newton (2006) states that microtine  
crashes often happen quickly following high populations.

Owls: The high small mammal populations last summer in central and  
northern Ontario meant that most owls had an excellent breeding  
season with abundant prey to feed growing young. Note that most  
northern forest owls are rarely if ever affected by cold temperatures  
and deep snow unless they are starving. Small mammal populations  
(mainly voles) drive their breeding, abundance and movements.

Northern Saw-whet Owl: A red-backed vole (preferred prey in Ontario)  
and deer mouse crash likely account for the very large flight this  
fall with hundreds recorded at banding stations.

Boreal Owl: I'm not aware of any Boreal Owl sightings this fall in  
Ontario, but the heavy flight of Saw-whets and low vole numbers  
suggest some may come south. Boreal Owls can take larger prey than  
Saw-whets such as Northern Flying Squirrels. Two Boreal Owls have  
been banded so far this fall at L'Observatoire d'oiseaux de Tadoussac  
northeast of Quebec City on the north shore of the St. Lawrence  
River. The observatory is situated along the migratory route of the  
Boreal Owl. This cyclic owl often moves only short distances so it is  
best monitored by northern observatories.

Great Gray Owl: One was seen on 19 November near Peterborough in  
central Ontario and another possible recent sighting in Muskoka. The  
crash of meadow voles (preferred prey in Ontario) in northern Ontario  
may cause more to show up farther south. However, Great Grays have  
the uncanny ability to find areas with high vole densities. They stop  
moving when they find abundant voles.

Barred Owl: They are moving, with several reports along north shore  
of Lake Ontario, away from their normal habitats. This movement is  
likely linked to a crash of red-backed voles, deer mice and other  
small mammals in the Great Lakes - St. Lawrence Forest and southern  
Boreal Forest.

Northern Shrike: The big southward movement this fall is probably  
resulted from the meadow vole crash in the boreal forest. Although  
Northern Shrikes eat small birds; they are mainly a vole specialist  
in winter. Birds are a buffer and form a greater proportion of  
Northern Shrike prey when voles are scarce.

Boreal Chickadee: Indicators of a small movement include Bob  
Knudsen's report yesterday from Sault Ste. Marie to Ontbirds, a flock  
of 13 seen recently by Erwin Meissner near Massey west of Sudbury,  
and a report from Stephen O'Donnell of more sightings than usual near  
Sundridge north of Huntsville. A few may get as far south as Lake  
Ontario. Boreal Chickadees prefer thick conifers especially spruce.  
Listen for their husky calls among flocks of Black-cappeds, which had  
a significant southward movement this fall.

Common and Hoary Redpolls - Subspecies: This year's big flight is  
providing an opportunity to study two subspecies of the Common  
Redpoll and perhaps two subspecies of Hoary Redpoll. Check link below  
to Tommy Thompson Park Bird Research Station in Toronto http:// 
www.ttpbrs.ca/ This site has recent photos of two subspecies of the  
Common Redpoll (flammea and rostrata) and photos of a Hoary Redpoll  
(subspecies exilipes). They call the rostrata subspecies the  
"Greenland" subspecies of the Common Redpoll, but the common name  
used in most of the literature for rostrata is "Greater" Common  
Redpoll. The name Greenland Redpoll was normally restricted to the  
nominate subspecies hornemanni of the Hoary Redpoll. Sibley (2000)  
adds to the confusion by using Greenland for the northern subspecies  
of both Common and Hoary Redpolls. I suggest not using Greenland  
Redpoll because it is now used for the subspecies both species. In  
fact, both rostrata Common Redpoll and nominate hornemanni Hoary  
Redpoll have extensive breeding ranges in Canada so why even mention  
Greenland, which is misleading.

	The "Southern" Common Redpoll (flammea) is the commonest redpoll in  
southern Canada. It breeds as close as northern Ontario. The  
"Greater" Common Redpoll (rostrata) breeds on Baffin Island and  
Greenland. The "Greater" Common Redpoll is normally a winter visitor  
in small numbers. Rick Poulin (reported by Pittaway 1992)) banded  
hundreds of redpolls in the 1980s near Ottawa and found "Greater"  
Common Redpolls more common than Hoarys during some winters.

	The "Southern" Hoary Redpoll (exilipes) breeds in the low Arctic  
south to extreme northern Ontario. It is the usual Hoary seen in  
southern Canada in winter. "Hornemann's" Hoary Redpoll is the rarest  
redpoll in southern Canada. It breeds in high Arctic Canada and  
Greenland. Classic adult males are very large and overall much whiter  
with less streaking on the sides, and immaculate undertail coverts.  
Adult males have less pink with some having a mere trace of a pink  
suffusion on the breast. Not all redpolls will be identifiable to  
subspecies or even species, but most individuals can be distinguished  
with considerable confidence.

Acknowledgements: I thank the following for keeping me informed: Ken  
Abraham (OMNR), Michel Gosselin (Canadian Museum of Nature), Jean  
Iron (Toronto), Erwin Meissner (Massey, Sudbury District), Marty  
Obbard (OMNR), Stephen O'Donnell (Sundridge, Parry Sound District),  
Don Sutherland (OMNR), Ron Tozer (Algonquin Park), Mike Turner  
(Haliburton Highlands) and Kirk Zufelt (Sault Ste. Marie, ON).

Literature Cited and Websites
Newton, Ian. 2006. Advances in the study of irruptive migration.  
Ardea 94(3): 433-460. This is the most informative paper on irruptive  
species by a winter finch and raptor expert.
Pittaway, R. 1992. Recognizable Forms: Redpolls. Ontario Birds 10(3):  
108-114.
Sibley, D.A. 2000. The Sibley Guide to Birds. Alfred A. Knopf, New York.
Tommy Thompson Park Bird Research Station, Toronto, Ontario. Website  
http://www.ttpbrs.ca/
Winter Finch Forecast 2007-2008. Archived at http://www.ofo.ca/reports 
%20and%20articles/winterfinches.php

Ron Pittaway
Minden & Toronto ON
jeaniron at sympatico.ca

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