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In 2006 we began noticing a rather unusual
molt in hatch-year Song Sparrows. After careful documentation over two
fall migration monitoring seasons, we submitted a paper describing
what we termed the 'eccentric plus primary coverts' molt to North
American Bird Bander. As a complement to that article, we present
below some colour photographs illustrating this molt pattern, as
observed at McGill Bird Observatory, in Montreal, Quebec.
This Song Sparrow was banded in early August 2006 and was
distinctly in juvenile plumage at the time. Upon recapture
on August 25, it was seen to be replacing its primary coverts
sequentially, along with the corresponding primaries. Such
a pattern of feather replacement was believed to occur only
during second and subsequent prebasic
moults, but as this bird has shown, there is still a lot to be
learned about even the most common species. (Photo by
Seabrooke Leckie)
The photos above and below show the left and right wings of the
same individual captured in August 2007. This individual shows a
symmetrical 'eccentric plus primary covert' wing molt. Note the
difference in length of the growing primaries and corresponding
primary coverts in both wings, highlighting the occurrence of
this molt and making it easy to spot. (Photos by Barbara
Frei)
Note the sheathed feathers coming in,
both the longer primaries and shorter corresponding primary
coverts. (Photo by Seabrooke Leckie, August 2006)
Again note the sheathed feathers (both
primaries and corresponding primary coverts) coming in, this
time longer and easier to see and differentiate. (Photo by
Seabrooke Leckie, September 2006)
A close-up of the tiny sheathed
primary coverts being grown in over their corresponding primary
coverts in a hatch-year Song Sparrow. (Photo by Seabrooke
Leckie, September 2006)
A selection of Quebec
region hatch-year birds at the Canadian Museum of Nature.
(Photo by Marie-Anne Hudson)
A selection of Ontario
region hatch-year birds at the Canadian Museum of Nature.
(Photo by Marie-Anne Hudson)
The one
example found of a hatch-year Song Sparrow showing the
'eccentric plus primary covert' molt described in our submitted
paper. It is likely that there were more in the
collection, however determining whether this unusual molt has
occurred on a closed wing is very difficult. We decided to be
very conservative and only use birds actively molting to
document this molt's historical occurrence in our region.
(Photo by Marie-Anne Hudson)
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