Migration Research Foundation - McGill Bird Observatory - Photo Library

McGILL BIRD OBSERVATORY

PHOTO LIBRARY

Black-and-white Warbler (Mniotilta varia)

Seasonal status at MBO:

JAN

FEB

MAR

APR

MAY

JUN

JUL

AUG

SEP

OCT

NOV

DEC

common

fairly common

uncommon

rare

occasional

no records

QUICK TIPS:

1) Look at the primary coverts - on HY/SY birds they are brownish and contrast with the black greater coverts, while on AHY/ASY birds there is no contrast between the primary and greater coverts

2) Consider the overall plumage - males are entirely black and white, while females are a slightly paler dusky-black and flanks have a buffy tinge

3) Look at the throat - only males are marked with black

Ageing and sexing guidelines:

January - July:

ASY - M Black-and-white striped crown, upperparts and underparts. Black chin, throat and auricular.
ASY - F Similar to ASY-M but has gray auricular, white throat and grayish streaking on underparts.
SY - M Similar to ASY-F but has blacker streaking on sides and undertail coverts, and often more black on the throat.
SY - F Auricular, flanks and undertail coverts are buffy-whitish.

June - December:

AHY - M Black-and-white striped crown, upperparts and underparts. Black chin, throat and auricular tipped with white.
AHY - F Similar to ASY-M but has gray auricular, white throat and grayish streaking on underparts.
HY - M Similar to ASY-F but has blacker streaking on sides and undertail coverts.
HY - F Auricular, flanks and undertail coverts are buffy.

Ageing and sexing details:

after-second-year male

ASY males are very bold-looking birds, with a black auricular, chin and throat. The flanks are white with bold, black streaking.

The outer primary coverts are broad and truncate, and are dusky with distinct but thin gray edging. These should not contrast with the greater coverts, as they would in a younger bird. These criteria are the same for both males and females, however males have black, not dusky, feather centres. Caution: a pseudolimit occurs in both HY and AHYs (tertials appear blacker than middle ss).

The outer rectrices are dusky, broad and truncate with moderate amounts of white.

RETURN TO AGE/SEX OVERVIEW

after-second-year female

ASY females are similar to ASY males, however the auricular is grayish/whitish rather than black. The flanks are tinged pinkish-buff, with indistinct and dusky streaking. The chin and throat are white.

The outer primary coverts are broad and truncate, and are dusky with distinct but thin gray edging. These should not contrast with the greater coverts, as they would in a younger bird. These criteria are the same for both males and females, however females have dusky, not black, feather centres. Caution: a pseudolimit occurs in both HY and AHYs (tertials appear blacker than middle ss).

The outer rectrices are dusky, broad and truncate with little to moderate amounts of white.

RETURN TO AGE/SEX OVERVIEW

second-year male

SY males are similar to ASY females in that the auricular, chin and throat are grayish/whitish, however they can sometimes be blackish with white mottling. The flanks are whitish with fairly bold, blackish streaking. This streaking is often blurred but remains quite distinct.