[CT Birds] more on Redpolls
ghanisek at rep-am.com
Fri Jan 11 22:22:19 EST 2008
For those of you who can't get enough on Redpoll ID, below is some more information posted on a different listserv by Ron Pittaway, a keen student of this group who lives in Ontario.
David Sibley wrote on Monday, "there are lots of aspects (about
redpolls) that could benefit from open discussion." Here are some
comments resulting from his post and blog...
1. Taxonomy: Troy (1985) concluded that the southern subspecies
(race) of Common Redpoll (Carduelis flammea flammea) and southern
subspecies of Hoary Redpoll (C. hornemanni exilipes) were one
variable taxon. Later researchers questioned Troy's conclusions.
Seutin et al. (1989, 1992, 1993) noted that age dimorphism was not
taken into consideration. Based on biochemical evidence, Marten and
Johnson (1986) found that southern Common (flammea) and southern
Hoary (exilipes) "seem to have split 550,000 years ago." Knox (1988)
found no evidence of hybridization, but suspected that it occurs
occasionally. The AOU (1998) and Knox and Lowther (2000) in the Birds
of North America do not follow Troy's conclusions. Lumping redpolls
has not been discussed for many years.
2. Redpoll Variation: Adults and juveniles have a prebasic molt in
late summer and early fall. Fresh fall basic plumages are much paler
than summer birds. Redpolls do not have an alternate plumage. They
acquire a darker breeding dress by feather wear. A large winter flock
of southern Common Redpolls (nominate flammea) can have four plumage
types: adult males, first year males, adult females, first year
females, plus individual variation. Add southern Hoary Redpolls
(exilipes) to the mix and the potential plumage types doubles to
eight. Now add "Greater" Common Redpolls (rostrata) which are
widespread this winter. "Hornemann's" Hoary Redpoll (nominate
hornemanni) is also being reported this winter.
3. Redpoll Index: It is misleading to compare the fresher and paler
redpolls seen in fall/winter with the much darker worn summer birds
used by Troy (1985). Fall and winter birds are a lot less confusing,
and the confusing ones are mainly females and first year birds. Many
difficult birds in photos currently being discussed are not that
difficult, they are simply not shown properly because of bad angles,
overexposure, underexposure, and inadequate comparisons. The
difficulties of identifying redpolls are overstated. Redpolls are no
more difficult than other groups such as peeps, dowitchers, and
gulls, but it is often difficult to view and photograph redpolls.
Most birders in the United States (Lower 48) and extreme southern
Canada are not familiar with Hoary Redpolls. Some are trying to turn
slightly lighter Commons into Hoary Redpolls, while others are
hesitating to identify obvious Hoarys.
4. Hoary Redpoll ID: Adult males are easily identified. Most
non-adult males also can be identified with practice by a combination
of characters: much whiter overall coloration, very lightly streaked
to immaculate undertail coverts, white rump, shorter more obtuse
bill, etc. The treatment of redpolls in the Sibley Guide (2000) is
excellent and relevant. Some redpolls are best left unidentified, but
with experience you will be able to identify more non-adult male
Hoary Redpolls such as this one in Quebec
three more non-adult male Hoary Redpolls
5. Hoary Redpoll status east of Hudson Bay: Reports that the Hoary
Redpoll (exilipes) is a rare or absent breeder east of Hudson Bay are
based on very few surveys in this vast area. However, the habitat
east of Hudson Bay is smaller than west of Hudson Bay.
Acknowledgements: Michel Gosselin, Jean Iron and Ron Tozer provided
comments and suggestions.
Literature Cited: I can supply full references.
Minden and Toronto, Ontario
More information about the CTBirds