Winter finches

Common Redpolls and Pine Grosbeaks
These two irruptive species are common throughout central Ontario this winter. To some, these movements may seem erratic but they're not. The so-called "irruptions" of northern bird species are caused by failures of staple food crops in the boreal forest and beyond. Ron Pittaway has acquired some expertise in predicting the movements of "northern birds". His 2007-2008 Winter Finch Forecast is spot-on.

Winter finch arrivals

Each winter brings a new mix of birds to the feeders outside our windows. A flock of 100+ Common Redpolls, accompanied by Pine Siskins and Common Goldfinches, ate nearly 50 kg of niger seed during the winter of 2005-2006. Last year, we didn't see a single Common Redpoll or Evening Grosbeak. This year is another story altogether.

Evening Grosbeaks first appeared in September and have stayed. Presently, we have two or three flocks totaling about 50 birds.
Common Redpolls now festoon the niger silo and the snow beneath. A few of the paler Redpolls may indeed be Hoary Redpolls but there seem to be intermediately coloured birds as well. Some day soon I will step up to meet Jean Iron's Redpoll Challenge, which involves learning to recognize the four redpoll subspecies presently wintering in Ontario.

This year-to-year variation makes backyard birding all the more interesting. To some, these movements may seem erratic but they're not. The so-called "irruptions" of northern bird species are caused by failures of staple food crops in the boreal forest and beyond. Ron Pittaway has acquired some expertise in predicting the movements of "northern birds". His 2007-2008 Winter Finch Forecast is spot-on.

Cerulean Warblers in cottage country

Courtesy of Lana Hays
We were delighted to find at least two Cerulean Warblers (Dendroica cerulea) singing in the hardwood forest less than a kilometre from our back door. I recorded some sounds from the first bird we found singing on May 21, 2007. On May 23, we found two males countersinging 300 m from where we made our May 21 observation. The video begins and ends with a Cerulean song. There's some Red-eyed Vireo (Vireo olivaceus) chatter in between.

This follows our observation of a single Cerulean Warbler in the same woodlot in May last year. We don't know whether they're actually breeding but the habitat - mature, mesic upland hardwood forest - corresponds to that utilized by well-studied breeding populations at the Queen's University Biological Station, 200 km to the east. We'll monitor the site over the next few weeks for signs of breeding.

The Cerulean Warbler is a species of special concern* in Canada, where the population is estimated to be only 500-1000 breeding pairs. Some populations in the United States have experienced precipitous declines. One of the threats to the Cerulean Warbler is the destruction of the tropical forests in which it, and a suite of other Neotropical migrant songbirds, spend the winter. This is one of the reasons we choose to buy shade grown coffee [on-line] from Birds and Beans in Toronto.

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Update - June 3, 2007. This species isn't unknown from the Kawartha Lakes. In the late 1990's, Cerulean Warblers were found breeding near Buckhorn, about 20 km east of us. As far as we know, they haven't been found there in recent years. We visited the area two days ago and located two singing Ceruleans as we drove slowly and listened through the open window of our vehicle, during the middle of the day. No doubt, there are more in the area.

The forests are similar to those near our home - second growth with a canopy largely enclosed by even-aged sugar maple. Just over a century ago, these lands were cleared for farmland; however, the soils are thin along the edge of the Canadian Shield and much of the land proved not to be arable. Succeeding generations from the pioneering families abandoned these farm fields allowing the forests to regenerate. Cerulean Warbler populations along the southern edge of the Shield appear to be benefiting, faring much better than those in the core of their range in the United States.

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* Special Concern - A species of special concern because of characteristics that make it particularly sensitive to human activities or natural events.

COSEWIC. 2003. COSEWIC assessment and update status report on the Cerulean Warbler Dendroica cerulea in Canada. Committee on the Status of Endangered Wildlife in Canada. Ottawa. vii + 25 pp. Available here.

Hamel, P. B. 2000. Cerulean Warbler (Dendroica cerulea). In The Birds of North America, No. 511 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.

Urban Long-tailed Ducks, in depth

A highlight of last weekend was the several hours we spent observing waterfowl in Toronto Harbour. Gadwalls (Anas strepera) , Mute Swans (Cygnus olor) and Red-breasted Mergansers (Mergus serrator) were among the common waterfowl we seldom observe at our inland home, about 200 km to the north. Most impressive were the rafts of Long-tailed Ducks (Clangula hyemalis) visible, and audible, throughout our visit. Some aspects of this bird's life history and charismatic presence in Toronto merit comment.
www.gregnewby.com.
Long-tailed ducks nest as far north as the 80th parallel - the highest of the high arctic, farther north than any other waterfowl (Robertson and Savard, 2002). Many winter on the Great Lakes with a significant number in the Toronto area. While these birds are quite at home in the rough, open waters of Lake Ontario, they appear to make a very good living in the inner and outer harbours created by the Eastern Headland (Tommy Thompson Park) and Toronto Island. A summary of Christmas Bird Count data for the past 25 years reveals just how hospitable the waterfront is to these visitors from the north. Three years ago, a record high of 13,938 Long-tailed Ducks was recorded. Low counts in the 1980's and 1990's likely resulted from the freezing of near shore waters in the city. In more mild recent winters, ice has not formed on Lake Ontario.

The call of the male has been variously transcribed as ahr-ahr-ahroulit, ahang-ahóo, ow owooolee, ow ow owoolik, or unk-on-alik, take your pick. Whereas other ducks may vocalize solely during courtship or during aggressive encounters, the yodelling notes of Long-tailed Ducks seem to accompany all aspects of their highly social lives.

Click here to hear a chorus of Long-tailed Ducks (.wav file), recorded in Toronto, courtesy of the Canadian Wildlife Service.

Whether flying our feeding, courting or resting, Long-tailed Ducks vocalize continually:the song is always in season. Surely these must be among the most garrulous of animals. Beyond its volume and ubiquity, the call has always struck me as exultant - a ringing lyric with overtones as ancient as the tundra.

No less remarkable than the male's vocal repertoire is its very elegant, stream-lined appearance. George Miksch Sutton and his colleague Olin Sewall Pettingill Jr., spent the summer of 1958 documenting the breeding birds of Iceland. Long-tailed Ducks, then known in North America as Oldquaws, were common on the tundra. Sutton's comments on Long-tailed Ducks echo some of the wonder we experienced as we watched these birds foraging along the Lake Ontario shoreline.

Sewall had a wonderful experience photographing the diving Oldsquaw. Perched with his camera on the cliff edge not far from Gudrún Pálsdóttir's house, he had been able to follow the bird as it moved gracefully about, had fed on the bottom, and finally come up with big eyes sparkling and water running down its sleek plumage. I had watched many diving Oldsquaw in the American Arctic and knew how beautiful they could be.Iceland Summer (p. 93).

While Martha and I strolled along the boardwalk just west of Wards Island, we lingered to observe about 50 very animated Long-tailed Ducks that were calling and diving only a few dozen metres offshore. They dove more-or-less synchronously, each leaving the surface with a clearly audible "plop". From our slightly elevated position, we could track each bird by the bubble trail reaching the surface. After about a minute below, the birds would bob topside, many calling or chortling with apparent enthusiasm. After only a few breaths, the birds commenced their next dive.
Long-tailed Ducks swimming toward shore at Ward's Island

Long-tailed Ducks are perhaps the deepest divers of their clan. On the Great Lakes, commercial fishermen have recovered tens of thousands of drowned Long-tailed Ducks from even their deepest gill net sets, some 70 metres below the surface - a vertical descent equivalent to the height of a 23 story office building. Associated with this hyperbaric extreme, Long-tailed ducks have the greatest heart muscle mass, gram-for-gram, of any duck, goose or swan (Bethke and Thomas, 1988).

On its wintering grounds, the species is known to exploit a range of animal prey, including epibenthic crustaceans, snails and, in soft substrates, oligochaete worms. We could only speculate on the nature of today's meal. Given the shallow break of the shore and the close proximity of the birds we observed, we supposed they couldn't have been feeding at more than a few metres depth. Offshore an additional 20 metres, a pair of Surf Scoters also dove. Each would surface with a single cluster of dreissenid mussels held in the fully gaped bill. The scoter would then break up the cluster and swallow, apparently with some effort, a smaller clump of mussels.

In contrast, the Long-tailed Ducks, diving in shallower water, surfaced with nothing in their bills, suggesting that they were eating smaller, more easily manipulated prey. One possibility, given the time of year and the characteristics of the site, is that they were eating the freshly spawned eggs of Lake Herring (Coregonus artedi). While fish eggs have not yet been documented in the diet of wintering populations of Long-tailed Ducks in North America, a recent study in the Baltic Sea, off Lithuania, found that this species opportunistically exploited the "energy-rich" eggs of Baltic Herring (Clupea harengus membras) during the April spawn (Zydelis and Ruskyte, 2005).

Whillans (1979) noted that between 1880 and 1893, large numbers of gravid Lake Herring were harvested along the shore of Toronto Island. The stock disappeared over a century ago and to my knowledge, has not recovered. The return of spawning Lake Herring to these shores would certainly be noteworthy.

These highly energetic flocks of Long-tailed Ducks provide a glimpse of something truly wild - a very scarce commodity in such a built up metropolis. Against a backdrop that includes the CN Tower and completely industrialized port lands, it is deeply satisfying to note that the wild, exuberant presence of these birds is in no way diminished.

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Charlie over at 10,000 Birds has compiled a stunning gallery of Long-tailed Ducks images taken on a sunny afternoon in Toronto Harbour - a must see!

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Image Credits:
Photo Credits: Photo of male Long-tailed Duck (top) used with permission from Greg Newby Photography.
Christmas Bird Count graphic by Michael. Other Long-tailed Duck photos by Martha.
Citations:
Bethke, R.W. and V. G. Thomas. 1988. Differences in flight and heart mass among geese, dabbling ducks, and diving ducks relative to habitat use. Canadian Journal of Zoology. 66: 2024–2028.
National Audubon Society (2006). The Christmas Bird Count Historical Results [Online]. Available at http://www.audubon.org/bird/cbc.
Robertson, G. J., and J.-P. L. Savard. 2002. Long-tailed Duck (Clangula hyemalis). In The Birds of North America, No. 651 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.
Sutton, G.M. 1974. Iceland Summer. University of Oklahoma Press, Norman.
Whillans, T.H. 1979, Historic transformation of fish and communities in three Great Lakes Bays. Journal of Great Lakes Research 5(2):195-215.
Zydelis, R. and D. Ruskyte. 2005. Winter foraging of Long-Tailed Ducks (Clangula hyemalis) exploiting different benthic communities in the Baltic Sea. Wilson Bulletin 117(2):133-141.

Surf Scoter

Human activity on the lake subsides markedly after Labour Day. The ski boats and personal watercraft have been stored for the winter and most of the cottagers won't return until late May. On this calm and sunny afternoon we crossed wakes with only a few fishing boats.

We were delighted to encounter a lone Surf Scoter, Melanitta perspicillata, swimming in about 10 metres of water, perhaps a kilometre from shore. While she wouldn't allow us to approach closer than a few boat lengths, she was quick to tuck her bill under her wing when we were more distant. Perhaps she was resting after a long flight from it's northern breeding range.

Of the three scoter species we've seen on the lake, this is the only one whose range is confined to North America.

Citations:
Savard, J.-P. L., D. Bordage, and A. Reed. 1998. Surf Scoter (Melanitta perspicillata). In The Birds of North America, No. 363 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.

Cooper's Hawk takes Rock Pigeon

Click to view a substantially larger image.
Almost all of the birds we observe at our feeders are the native species one would expect in cottage country. Exceptions include three European Starlings (Sturnus vulgaris) that showed up for the first time this past month. Only once before have Martha and I seen feral Rock Pigeons (Columba livia) from our property, a high-flying flock that wheeled over our bay, heading west in high gear last September. We know of a few small flocks, several km to the north and south, that take advantage of the shelter and nesting opportunities afforded by bridges along Highway 28. Perhaps it was such an overflying trio that observed the many Common Grackles (Quiscalus quiscula), Brown-headed Cowbirds (Molothrus ater) and Red-winged Blackbirds (Agelaius phoeniceus) at our feeders on April 23rd. The pigeons landed, tasted the cracked corn and so joined the list of 30 or so other species we've observed at the feeders. Since then, the same three Rock Pigeons have visited two or three times each day.

Late this morning, I glanced out the window and saw the three Rock Pigeons feeding along side a mixed flock of 30 or so blackbirds. The birds suddenly scattered - they are often startled by the construction-related traffic at the barge landing on our neighbour's lot. I then saw a fair-sized bird make contact with one of the fleeing Rock Pigeons and the two cartwheeled to the grass, just down slope from the feeders.

I called Martha from the kitchen and over the next five minutes, we watched the Cooper's Hawk (Accipiter cooperii) subdue and pluck the hapless dove. We were able to get a few blurry pictures by "digiscoping" our Coolpix 4500 against an 8 x 40 binocular objective. Our observations ended when an approaching motorboat flushed the hawk, which flew down slope to the east with its prey in its talons.

The pictures convey the rest of the story.

Our resident Canada Geese, celebrated below in their routing of a Red Fox, were unruffled by this particular predator. Indeed the two geese approached, on webbed feet, to within five metres of the hawk and quietly observed the pigeon's demise.

The two other Rock Pigeons returned to the feeder an hour or so later.

Tho' nature, red in tooth and claw

Portions of small mammal skulls from a single owl pellet
Every few months we hear the call of the resident Barred Owls and a few times, I've caught glimpses of them flying across the beams of the truck headlights. This winter, a few Great Gray Owls were in the area and on Long Lake Road, only a few kilometres to the north of us, a cottager found an injured Boreal Owl under a window last month. Overall, I think our encounters with any of the resident species are rare.
Martha spotted an intact owl pellet lying beneath a Hemlock deep in the woods. 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. Not represented here are members of the subfamily Crocidurinae, or White-toothed Shrews, a taxon comprised of species not found in the New World.

The first and third partial skulls are likely from Northern Short-tailed Shrew (Blarina brevicauda. The second (middle) skull is likely from a Meadow Vole (Microtus pennsylvanicus). These two widespread species are common in the area.

Acknowledgements

The title of the entry was borrowed from In Memorium A.H.H, by Alfred Lord Tennyson (1850).

Goose Step and Fox Trot

Our shoreline was particularly busy during one evening last week. A pair of Wood Ducks (Aix sponsa) and a male Ring-necked Duck (Aythya collaris) gorged on cracked corn near the water's edge. Small courting parties of Bufflehead (Bucephala albeola) and Hooded Merganser (Lophodytes cucullatus) squabbled and paraded in the thawed margins of the bay.

The highly animated sights and sounds of courting Hooded Mergansers are not easily forgotten. Dugger et al. (1994) gave this account:

Head-throws, the most elaborate display, are usually performed with the male parallel to the intended female. With crest raised, males bring their head abruptly backward touching their back. A rolling frog-like crraaa-crrrooooo call is given as the head is returned to the upright position and turned away from the intended female.

More extraordinary was the drama that unfolded between a Red Fox, (Vulpes vulpes) and the resident pair of Canada Geese (Branta canadensis). Late in the afternoon a bedraggled fox coursed across our lot and stopped to glean small bits of suet that had fallen to the ground beneath our bird feeders. Soon, its attention was drawn to a pair of Canada Geese resting on the shoreline. And that is when things got more interesting.

But first, here's a little background on the responses of the local waterfowl to the approaches of (bipedal) mammals. Typically, when we walk down to the waterfront, the ducks and geese disperse. Buffleheads and Mergansers skitter into flight and disappear for an hour or more. The Wood Ducks also take flight, squealing as they wheel back into the wetland. The geese and Mallards generally swim out from shore and return soon after we've left.
Canada Geese repelling Red Fox. Photos by Martha.
On this day, with this potential threat, the geese responded very differently. Instead of swimming to immediate safety, the geese stepped up on shore and approached the fox while honking and hissing, standing in single file (see photo). The fox feinted to one side, and then the other, but these moves did not expose a vulnerable flank. Instead, the geese honked more loudly and the lead goose spread its wings while continuing to approach the predator. The second goose, standing directly behind its mate, remained in lock step.

This was all too much for the fox. It broke off the engagement and headed east, likely in search of easier fare.

Why did the geese make such a grand stand, and put so much energy into routing the fox, when they might have simply swam out of harm's way?

In an evolutionary sense, fox and geese are no strangers. In the Canadian arctic, where the ecology of nesting geese has been most closely studied, Arctic foxes (Alopex lagopus) can be significant predators.
Lesser Snow Goose gander repelling Arctic Fox. Photo by Gustaf Samelius.
Nests defended by two adult Lesser Snow Geese (Chen caerulescens), a smaller species, are virtually invulnerable to foxes [Learn more about this research here].

Nests defended by only a single parent are more easily predated (Samelius and Alisauskas 2001). Perhaps fox predation helped shape the evolution of the colonial nesting habit, and other behaviours, among ground nesting geese.

Perhaps what we witnessed on this evening was the "release" of an anserine defensive repertoire that evolved primarily as a response to foxes. Perhaps this goose-stepping and fox-trotting are moments in a very ancient performance, danced by two intimate evolutionary partners.

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Citations:
Dugger, B. D., K. M. Dugger, and L. H. Fredrickson. 1994. Hooded Merganser (Lophodytes cucullatus). In The Birds of North America, No. 98 (A. Poole and F. Gill, Eds.). Philadelphia: The Academy of Natural Sciences; Washington, D.C.: The American Ornithologists’ Union.
Samelius G. and R.T. Alisauskas. 2001. Deterring arctic fox predation: the role of parental nest attendance by lesser snow geese. Canadian Journal of Zoology: 79: 861-866. Abstract.
Photo Credits:
Hooded Merganser courtesy of Susan Allen.
Lesser Snow Geese defending against Arctic Fox courtesy of Gustaf Samelius. Learn more about this research here.