Which feathers make up the black patch on a Northern Pintail?
On a swimming male Northern Pintail in basic (bright) plumage there is
often a black patch visible on the side, just below the long scapulars.
On the pictures of flying birds in Sibley and Nat Geo the only dark
feathers shown on the wings and back are the secondaries. The patch
seems to far in the front though for being secondaries. So what
feathers are those?
I spent a few happy hours looking at photographs on the internet. On
some flying or mounted birds a black patch was visible between the wing
and the elongated scapulars. I suspected that those were outer
scapulars. Links to some of the photos I found follow further down.
The Handbook of the Birds of Europe, the Middle East and North Africa
"Outer scapulars black, streaked cream
or buff-grey on inner web and along shaft; elongated lower scapulars
black, broadly edged cream. Lower scapulars partly vermiculated grey."
Incidentally, Sibley uses a Northern Pintail to illustrate duck feather
groups in his "Birding Basics" on page 88. He points out the black
patch as the secondary coverts there, which is wrong!
Comparison to the white patch on wigeons
It is very interesting to
compare the black patch on the Northern Pintail to the white patch on
the wigeons, which looks to be in almost the same place on a resting
The white patch on wigeons consists of the greater coverts. (Had
Sibley illustrated a wigeon he would have been right.)
This means that they are only molted once a year when the wings are
molted in the summer while the bird is in eclipse plumage. The white
patch is thus present year round, it is also visible on eclipse plumage
It is on the other hand not present in males in their first cycle yet.
Wigeons in their first basic (=juvenal) plumage have mottled gray
greater coverts. The wing feathers are retained while the body feathers
are molted in the formative molt which results in the formative (=
first bright or first winter) plumage of the body. In the early summer
the birds go through another body molt, the first alternate (eclipse)
plumage, while the first basic wing feathers are still retained. While
having this alternate body plumage the birds start their second basic
molt by molting their wings during the summer, now for the first time
acquiring white greater coverts. Soon after the wing molt the basic
molt proceeds with the body feathers and the birds acquire their bright
The black patch on Northern Pintail consists of the outer scapulars,
which are body feathers.
This means that they are molted twice a year. In basic (bright) plumage
their visible outer webs are all black. In alternate (eclipse) plumage
they are not, they do not have the black patch in alternate (eclipse)
Northern Pintails should also have the black patch in their formative
(= first bright or first winter) plumage, since it consists of body
feathers and body feathers are molted in the preformative molt. I have
not been able to explicitly confirm this though. Exceptions are always
possible. The possible exceptions in this case would be that the
formative outer scapulars do not have completely black outer webs or
that the scapulars are not molted in the birds' preformative molt, that
first basic (= juvenal) scapulars are retained until a later molt.
(I have followed Peter Pyle's plumage terminology proposed in his paper
"Molts and Plumages of Ducks", Waterbirds 28(2), 2005)
Photographs of Northern Pintails showing the outer scapulars
Photos of swimming or standing birds showing both the speculum and
black outer scapulars are here, here, here, here, here and here.
Though most often visible, the black scapular patch can be concealed
under body feathers just like the rest of the wing. Some examples of
birds showing their speculum but not their black scapular patch are here, here and here.
Flying birds showing the black outer scapular patch are here, here, here, here