2

Winter finch forecast

Drew Weber|

Ron Pittaway just released his latest winter finch forecast. The full text of his forecast is below. For PA, it looks like Purple Finches and Common Redpolls will be moving south  and we will hoepfully find good numbers of both. Red-breasted Nuthatches are also moving south this year. Finches such as the crossbills, Pine Grosbeak and Evening Grosbeak are forecast to stay north where seed crops were good this year.

Ron Pittaway’s Winter Finch Forecast 2010-2011

This winter’s theme is that some finch species will irrupt into southern Canada and the northern United States, while other species will remain in the north. As an example, Common and Hoary Redpolls will move south whereas Pine Grosbeaks will stay in the north. See individual finch forecasts below for details. Three irruptive non-finch passerines are also discussed.

Key Finch Tree Crops

Key trees in the boreal forest affecting finch abundance and movements are white and black spruces, white birch, and mountain-ashes. South of the boreal in the mixed coniferous/deciduous forest region, white pine and hemlock are additional key finch trees. Other trees play a lesser role, but often boost or buffer main seed sources. These include
tamarack (American larch), balsam fir, white cedar, yellow birch and alders.

SPRUCE: White spruce cone crops are very good to excellent across the northern half of the boreal forest in Canada, except Newfoundland where crops are poor. However, spruce crops are much lower in the southern half of the boreal forest and poor in the mixed forest region of central Ontario such as Algonquin Park. The spruce crop is good to very good in central and northern Quebec, but generally poor in Atlantic Canada and northeastern United States. Spruce cone abundance is very good in the foothills of Alberta and eastern side of the Rocky Mountains in Canada, but poor in the southern half of British Columbia and in Washington State. A bumper white spruce cone crop in southern Yukon attracted high numbers of White-winged Crossbills and Pine Siskins this past summer and they may remain there through the winter. Spruce crops are generally poor in the Atlantic Provinces, New York State and New England States.

WHITE PINE: Cone crop is spotty with scattered good to excellent crops across Ontario. White pine crops are low in Atlantic Canada, New York and New England States.

HEMLOCK: Cone crop is poor in Ontario and elsewhere in the East.

WHITE BIRCH: Crop is poor across the boreal forest of Canada and in central Ontario, but birch crops are much better
in southern Ontario south of the Canadian (Precambrian) Shield.

MOUNTAIN-ASH: Berry crops are generally excellent across Canada and Alaska, but poor in Newfoundland.

Individual Finch Forecasts

Forecasts apply mainly to Ontario, but neighboring provinces and states may find they apply to them.

PINE GROSBEAK: The Pine Grosbeak breeds in moist open habitats across northern Ontario. It is most common in northeastern Ontario which receives more precipitation than northwestern Ontario (Peck and Coady in Atlas of Breeding Birds of Ontario 2007). Most Pine Grosbeaks should stay in the north this winter because the mountain-ash berry crop is generally excellent across the boreal forest of Canada and Alaska, except for a poor crop in Newfoundland. The feeders at the Visitor Centre in Algonquin Park usually attract Pine Grosbeaks even in non-flight winters. If Pine Grosbeaks wander into southern Ontario they will find good crops of European mountain-ash berries and ornamental crabapples.

PURPLE FINCH: This finch winters in the north when the majority of deciduous and coniferous seed crops are abundant, which is not the case this year. Most Purple Finches will migrate south of Ontario this fall. A few may frequent feeders in southern Ontario. Purple Finch numbers have declined significantly in recent decades due in part to a decrease of spruce budworm outbreaks since the 1980s (Leckie and Cadman in Atlas of Breeding Birds of Ontario 2007).

RED CROSSBILL: This crossbill comprises at least 10 “call types” in North America. Each type has its particular cone preferences related to bill size and shape. These crossbill types may be at an early stage of evolving into full species and some may already qualify for species status. They are exceedingly difficult to identify in the field and much remains to be learned about their status and distribution. Types 2 and 3 and probably 4 occur regularly in Ontario (Simard in Atlas of Breeding Birds of Ontario 2007). Most Red Crossbill types prefer pines, but the smallest-billed Type 3 (sitkensis subspecies of AOU Check-list 1957) prefers the small soft cones of hemlock in Ontario. It will be absent
this winter because hemlock crops are poor. Type 2 may be the most frequently encountered Red Crossbill in the province. Some Type 2s should be found this winter where white pine crops are very good such as northeastern Algonquin Park and along Highway 69 north of the French River in Sudbury District. Possible this winter are other Red Crossbill types associated with red pine, which has some locally good crops.

WHITE-WINGED CROSSBILL: High numbers of White-winged Crossbills are currently concentrated in southern Yukon where the white spruce cone crop is bumper. These may remain there this winter. This crossbill’s highest breeding abundance in Ontario is in the spruce dominated Hudson Bay Lowlands and adjacent northern Canadian Shield (Coady in Atlas of Breeding Birds of Ontario 2007). Most Ontario reports this past summer came from this area where the white spruce cone crop is heavy. Some were singing and presumably nesting. They might remain in northern Ontario this winter if seed supplies last. Some may disperse southward as spruce seeds run low and could appear in southern Ontario and northern United States. However, they will be rare or absent this winter in traditional
areas such as Algonquin Park where spruce and hemlock cone crops are very poor. Unlike the Red Crossbill, the White-winged Crossbill has no subspecies (monotypic) or call types in North America. Its nomadic wanderings across the boreal forest mix the populations and allow gene flow, which inhibits geographical variation and the formation of
subspecies.

COMMON REDPOLL: Redpolls should irrupt into southern Canada and the northern United States this winter. The Common Redpoll’s breeding range in Ontario is mainly in the Hudson Bay Lowlands from the Manitoba border southeast to southern James Bay (Leckie and Pittaway in Atlas of Breeding Birds of Ontario 2007). Redpolls in winter are a birch seed specialist and movements are linked in part to the size of the birch crop. The white birch crop is poor across much of northern Canada. Another indicator of an upcoming irruption was a good redpoll breeding
season in 2010 with double and possibly triple broods reported in Quebec. High breeding success also was reported in Yukon. Samuel Denault of McGill University has shown that redpoll movements at Tadoussac, Quebec, are more related to reproductive success than to tree seed crops in the boreal forest. Redpolls will be attracted to the good birch seed crops on native white birch and European white birch in southern Ontario and to weedy fields. They should be frequent this winter at feeders offering nyger and black oil sunflower seeds. Watch for the larger, darker and browner “Greater” Common Redpolls (rostrata subspecies) in the flocks. It is reliably identified by its larger size and proportionally longer thicker bill and longer tail in direct comparison with “Southern” Common Redpolls (nominate flammea subspecies).

HOARY REDPOLL: The breeding population in northern Ontario is the most southerly in the world (Leckie and Pittaway in Atlas of Breeding Birds of Ontario 2007). Careful checking of redpoll flocks should produce a few Hoary Redpolls. There are two subspecies. Most Hoaries seen in southern Canada and northern United States are “Southern” Hoary Redpolls (exilipes subspecies). During the last large redpoll irruption in 2007/2008, several “Hornemann’s” Hoary Redpolls (nominate hornemanni subspecies) were found and supported by photographs. Hornemann’s Redpoll
was previously regarded as a great rarity south of the Arctic, but it may be more frequent than formerly believed. Hornemann’s is most reliably identified by its much larger size in direct comparison with flammea Common Redpolls or exilipes Hoary Redpoll. Note that white birds loom larger than life among darker birds and size illusions are
possible.

PINE SISKIN: Similar to the White-winged Crossbill, there are currently high numbers of siskins in southern Yukon attracted to a bumper white spruce cone crop. They could stay in Yukon for the winter. Siskins show a tendency for north-south migration, but are better considered an opportunistic nomad (Pittaway in Atlas of Breeding Birds of Ontario 2007). Banding recoveries show that siskins wander from coast to coast searching for conifer seed crops. They were uncommon this past summer in Ontario and the Northeast. Some might winter in northern Ontario where
the white spruce crop is heavy. However, siskins are currently uncommon in the Northeast so there are potentially only very small numbers that could irrupt south in eastern North America.

EVENING GROSBEAK: Highest breeding densities in Ontario are found in areas with spruce budworm outbreaks. Current breeding and wintering populations are now much lower than a few decades ago mainly because
large spruce budworm outbreaks have subsided since the 1980s (Hoar in Atlas of Breeding Birds of Ontario 2007). If some come south this winter, they will find large crops of Manitoba maple (boxelder) seeds and plenty of black oil sunflower seeds at feeders waiting for them.

Three More Irruptive Passerines

BLUE JAY: This will be an average flight year with smaller numbers than in 2009 along the north shorelines of Lakes Ontario and Erie. Beechnut crops are poor to none. Acorn crops are spotty, but considerably better than last year. More Blue Jays will winter in Ontario than last winter due to caches of acorns and other mast crops.

RED-BREASTED NUTHATCH: This nuthatch is a conifer seed specialist when it winters in the north, thus its movements are triggered by the same crops as the boreal winter finches. The southward movement, which began
in the summer, signaled the generally poor cone crops on spruces, balsam fir and white pine in the mixed coniferous/deciduous forest region across Ontario and in Atlantic Canada, New York and New England States.
Red-breasted Nuthatches will be very scarce this winter in central Ontario such as Algonquin Park. White spruce crops are excellent in the northern half of the boreal forest, but it is uncertain how many Red-breasted Nuthatches will winter that far north.

BOHEMIAN WAXWING: Most Bohemians Waxwings will stay close to the boreal forest this winter because mountain-ash berry crops are excellent across Canada, except in Newfoundland. Some should wander south to traditional areas of eastern and central Ontario such as Ottawa and Peterborough where planted European mountain-ashes and ornamental crabapples are frequent. If you get the opportunity to visit northern Ontario this winter, you may see Bohemian Waxwings and Pine Grosbeaks feeding together on mountain-ash berries. The grosbeaks eat the seeds and discard the flesh whereas the waxwings swallow the entire berry and sometimes eat the fleshy leftovers of the grosbeaks. The similar coloration of Bohemian Waxwings and female Pine Grosbeaks may be functional, perhaps reducing interspecific aggression when they feed together.

Enhanced by Zemanta