"Greater" Common Redpoll?

I'm pretty sure that this large male Common Redpoll is of the rostrata subspecies - larger, heavier billed and more boldly striped than the more common southern or flammea subspecies. I came upon this lone bird at the Marathon Cross-country Ski Club.

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Lake Superior in the Town of Marathon on a chilly morning

This is the view from Pebble Beach this morning. The steam off the lake is typical in the winter when the air temperature drops below -25 C.

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Daily visit by Pileated Woodpecker

This female PIWO is a daily visitor. She doesn't seem at all bothered by temps in the -30's (C). Photos taken through our kitchen window.

The log is also visited by Black-capped Chickadees, Downy and Hairy Woodpeckers, a Red-breasted Nuthatch and European Starlings.

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Shrike!

The growing redpoll flock in our yard has not gone unnoticed by a couple of Northern Shrikes. I have seen a few chases but no captures. This brown tones indicate that this is a first year bird.

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Last week, nature blogger Penelope in Northfield, Minnesota caught a few great action shots of a dapper adult (grey, black and white) Northern Shrike wrangling a vole.

Small mammals at the bird feeder

While birds are our most conspicuous backyard visitors, the snow reveals signs of a community of mammalian visitors we seldom see. Often we find tiny tracks and a network of tunnels just under the surface. In their yard, our friends Christine and Kyle found similar tunnels, and the tunneler, active in broad daylight last weekend. We were all surprised to learn that the tunneler wasn't a rodent. Instead, it was a Northern Short-tailed Shrew (Blarina brevicauda)!

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Northern Short-tailed Shrew. Photo courtesy of Christine Drake

Northern Short-tailed Shrew. Photo courtesy of Christine Drake
Northern Short-tailed Shrew. Photo courtesy of Christine Drake

Armed with poison-secreting salivary glands, Northern Short-tailed Shrews are well-known predators of small rodents and invertebrates. They are also known to eat bird seed and are commonly encountered in the vicinity of bird feeders.

One consequence of concentrated small mammal activity in the yard is the attraction of larger predators, as Jo-Ann Ecker of Woodstock, Vermont observed after a snow storm on January 12th. Jo-Ann wrote:

Our Barred Owl waits for white footed mice and voles to appear. I am sure he is successful or else he wouldn't come back.

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Barred Owl. Photo courtesy of Jo-ann Ecker

Barred Owl. Photo courtesy of Jo-ann Ecker

A few years ago, Martha spotted an intact Barred Owl pellet lying beneath a Hemlock in the woods, beyond our yard. When we teased it apart, we found the remains of at least three small mammals.

Two of the partial skulls and a single mandible are from shrews (family Soricidae) of the subfamily Soricinae, also known as the red-toothed Shrews. The reddish colour is the result of iron deposited in the tooth enamel.

The first and third partial skulls are likely from a Northern Short-tailed Shrew. The second (middle) skull is likely from a Meadow Vole (Microtus pennsylvanicus). These two widespread species are common in the area, although the shrew is approaching the northern limit of its Ontario range on the the north shore of Lake Superior.

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Just to the south of us, in Northfield, Minnesota, fellow nature blogger Penelope has been documenting the behaviour of a Northern Short-tailed Shrew under her bird feeders.

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Here is an excellent series of photos and description of the discovery of a Northern Short-tailed Shrew skeleton in a Saw-whet Owl pellet at the Lake Erie Metropark (MI).

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Many thanks to Christine Drake and Jo-Ann Ecker for sharing their terrific photos.

Two Common Ravens and a Pine Grosbeak - birds with a circumboreal distribution.

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This is a very typical scene in our backyard. It includes two species (Common Raven and Pine Grosbeak) and a distinctive genus (birch -  Betula) which can be found together in Canada, Greenland, Scotland, Finland, Russia, Mongolia and China and elsewhere.

Sharp-tailed Grouse on the Black Bay fen

Greg Stroud toughed it out a -32 C windchill last Saturday (Jan 15) and turned up five Sharp-tailed Grouse. Thanks for sharing the pictures Greg.

More on the Black Bay Fen here.

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Common Redpolls in the storm

The Redpolls seem to be holding their own in the current blizzard.

Pine Grosbeaks get their fill

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"Hornemann's" Hoary and "Greater" Common Redpolls

During the December 19th CBC we tallied a total of only eight Common Redpolls at two different feeders. Since then the redpoll scene has become more interesting. As noted in my last post, the backyard flock has grown and at times Hoary Redpolls appear to outnumber Common Redpolls.

A few days ago an unusual male Hoary Redpoll showed up in the late afternoon. It was much larger than the abundant Common Redpolls and 'exilipes' Hoary Redpolls in the yard - in particular, its large, heavy body made the head seem disproportionately small. This is a key characteristic of Hornemann's Hoary Redpoll, the rarest of the recognizable redpoll subspecies in Ontario.

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I took a quick burst of photos through our kitchen window and while viewing them later on the laptop, I noticed a couple of very large, heavily streaked Common Redpolls in a few of the frames - Greater Redpoll (Acanthis flammea rostrata)!

numbers refer to subspecies listed below

Accompanying the Hornemann's Hoary Redpoll and the Greater Common Redpoll was the more common (and smaller) "Southern" Common Redpoll.

In the larger flock in the yard were ten or more "Southern" (exilipes) Hoary Redpolls (see previous post).

Thus, I was fortunate enough to observe the four Ontario redpoll subspecies in the yard that day.

As numbered in the previous images, these recognizeable subspecies are:

1. "Southern" Common Redpoll (Acanthis flammea flammea)
2. "Greater" Common Redpoll (Acanthis flammea rostrata)
3. "Hornemann's" Hoary Redpoll (Acanthis hornemanni hornemanni)
4. "Southern" Hoary Redpoll (Acanthis hornemanni exilipes)

Here are a few more photos from the series. Again note the pallor and large size of the "Hornemann's" Hoary Redpoll in the centre. Also, note the similarly large size and dark streaking of the "Greater" Common Redpoll in the rear.

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I sent the photos off to noted winter finch prognosticator Ron Pittaway.  He and Michel Gosselin (Canadian Museum of Nature) confirmed the ID's. In print and in on-line publications, these two ornithologists have done much to advance our understanding of redpoll taxonomy and diversity in Canada. David Sibley has also made some great contributions to the subject. Please check the related resources (below) for a wealth of (mostly) on-line materiel.

Ron offered the following comment which may help to lessen confusion when we discuss redpoll subspecies:

Hornemann’s Redpoll and Greater Redpoll are the English common names used by the AOU when subspecies had official common names and I encourage their use today with the interest in recognizable forms. You may here some birders calling both subspecies as Greenland Redpolls, which is confusing and misleading. Both Hornemann’s and Greater Redpolls breed in Canada and the birds we get are mostly from the Canadian Arctic.

A final note on Hoary Redpolls currently in the Marathon area.

Yesterday (January 9, 2011) I walked through some of the scrubby bush beside the mill in Marathon and I came upon a flock of about 20 redpolls feeding on Green Alder seeds.

The birds were very focussed on their foraging and this allowed me the chance to observe most of them at close range - all of the 13 I could see were unambigously pale "Southern" (exilipes) Hoary Redpolls.

More photos of redpolls (including several more of the "Hornemann's" Hoary Redpoll) from our yard in January of 2011.

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Postscript: The story of the invasion by diverse redpolls into northern Ontario during the winter of 2010-2011 - in the format of a 'photo salon' - was featured in the winter issue of North American Birds. The article is available here (pdf).

It provides a thorough review of the finer points, and limitations, of redpoll identification.

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Acknowledgements

Many thanks to Ron Pittaway and Michel Gosselin for commenting on the redpoll identities in the above photos. I'm also grateful to Pete Read and Nick Escott for pointing out that one of the numbered birds in an earlier graphic was likely a CORE, not a HORE. This has been corrected.

Related resources

From Ron Pittaway

• 1992. Recognizeable Forms: Redpolls. Ontario Birds 10 (3):108-114 [pdf].
• Redpoll Challenge: four subspecies [an excellent summary and description of the four recognizeable subspecies found in Ontario].
• Photos of Hornemann's Hoary and Greater Common Redpoll.

From David Sibley

• A summary of redpoll subspecies.
• Redpoll identification.
• Photos of Greater Redpolls.
• Redpoll investigation widens to include "Greater".
• Urging caution when identifying Common Redpoll.  

Peer reviewed

• Knox, Alan G. and Peter E. Lowther. 2000. Hoary Redpoll (Carduelis hornemanni), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/544 doi:10.2173/bna.544,
• Troy, D.M. 1985. A phenetic analysis of the redpolls Carduelis flammea flammea and. C. hornemanni exilipes. Auk 102: 82-96 [pdf].
• Wetherbee, O.P. 1937. A study of wintering Hoary, Common, and Greater Redpolls, and various intermediates or hybrids. Bird-Banding 8(1): 1-10 [pdf].

Other

• Brinkley, E.S., Buckley, P.A., Bevier, L.R. and A.M. Byrne. 2011. Photo Essay: Redpolls from Nunavut and Greenland visit Ontario. North American Birds 65(2): 2-11 [pdf].
• From Jean Iron, excellent photos of Common Redpolls, Hoary Redpolls and Greater Common Redpolls.
• Excellent in-hand comparisons of Greater and Southern Common Redpolls from Toronto, taken by Seabrook Leckie.
• Great photos of a Hoary Redpoll taken in early January in nearby Hasty Brook, Minnesota. 
• If you're not yet confused and you can't get enough, check Andy Warr's detailed overview of redpoll subspecies (most of which we share) found in the UK.

Hoary Redpolls

We're back in Marathon and thanks to our friend Nancy, who tended our pets and feeders while we were away, our yard is full of winter finches. During our absence, the flock of Common Redpolls grew from six to about thirty, plus four or five Hoary Redpolls.

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Happy New Year to all!