Migration Research Foundation - McGill Bird Observatory - Photo Library

McGILL BIRD OBSERVATORY

PHOTO LIBRARY

Yellow-rumped (Myrtle) Warbler (Dendroica coronata)

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:

This species can be quite variable, and multiple characteristics are often required to be confident about age and sex:

	HY/SY female	HY-SY male	AHY-ASY female	AHY-ASY male
Back	mostly brownish	irregular mixture of brown and blue	relatively uniform mix of brown/gray/blue	bluish-gray
Uppertail coverts	narrow black centres, edging mostly brown	moderately wide black centres, mix of brown/blue edging	moderately wide black centres, mix of brown/blue edging	broad black centres, mostly to entirely blue edging
Rectrices	sometimes fairly narrow and pointed	sometimes fairly narrow and pointed	broad and rounded	broad and rounded
Primary coverts	brown, usually with minimal pale edging; often much paler than the greater coverts	brown, usually with minimal pale edging; often much paler than the greater coverts	gray, usually with distinct pale edging; often slightly paler than the greater coverts	gray, usually with distinct pale edging; often slightly paler than the greater coverts
Wing length	usually 65-75 mm	usually 65-75 mm	usually 70-78 mm	usually 70-78 mm

Note that especially in spring, it may not be possible to determine age for all individuals

Ageing and sexing guidelines:

Birds in all plumages have a yellow rump and a yellow patch on each side in front of the wing

January - July:

ASY - M Upperparts bluish gray. Bright yellow crown patch, white throat, black auricular and wide complete black breast band. Audubon's Warbler: similar, but with yellow throat; extent of white on the tail is greater
ASY - F Similar to ASY-M but duller, with more brown in plumage. Breast has distinct black streaking without a complete breast band.
SY - M Upperparts bluish gray, often tinged brownish. Breast has a wide, complete or nearly complete black band. Audubon's Warbler: similar, but with yellow throat; extent of white on the tail is greater
SY - F Upperparts and auricular brownish, sometimes tinged gray. Breast has indistinct black streaking without a complete black band. Some may lack yellow crown and side patches.

June - December:

AHY - M Upperparts blue, heavily washed grayish. Auricular often mottled with black.
AHY - F Upperparts usually tinged bluish gray. Auricular grayish without black mottling.
HY - M Upperparts usually tinged bluish gray. Auricular brownish without black mottling.
HY - F Upperparts overall brownish without gray. Auricular brownish without black mottling.

Ageing and sexing details:

after-second-year male

As for most species, ASY males are the brightest of all age and sex categories. Their upperparts are bluish gray, they have bright yellow crown patches, white throats, black auriculars and a wide complete, black breast band.

Photo by Marcel Gahbauer, McGill Bird Observatory, May 2006

Audubon's Warblers are similar in appearance, the most noticeable difference being the yellow instead of white throat.

Photo by Manon Dubé, Banff National Park, May 2007

The outer primary coverts are broad, truncate and dusky with distinct grayish edging. Note that there is often a moult limit in the greater coverts; the bird below was replaced all but the 3 outer coverts during its prealternate moult. The contrast, however, is clearly between 2 adult feathers (less of a contrast), and not an adult and a juvenal feather, making this bird an ASY. The second photo below is of an Audubon's Warbler; the white on the inner greater coverts and median coverts averages more extensive, but otherwise the characteristics are similar.

Photo by Marcel Gahbauer, McGill Bird Observatory, May 2006

Photo by Manon Dubé, Banff National Park, May 2007

The outer rectrices (r3-r6) are relatively fresh, somewhat truncate and are black with relatively large amounts of white. The second photo is of an Audubon's Warbler; the white patches are typically more extensive on this subspecies than for Myrtle Warblers.

Photo by Marcel Gahbauer, McGill Bird Observatory, May 2006

Photo by Manon Dubé, Banff National Park, May 2007

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after-second-year female

ASY females are similar to ASY-M but are duller and have more brown in their plumage. The breast has distinct black streaking without a complete breast band.

Photo by Marie-Anne Hudson, McGill Bird Observatory, May 2007

Photo by Marcel Gahbauer, McGill Bird Observatory, May 2005

The outer primary coverts are broad, truncate and dusky with grayish edging, though this may not always be clearly visible. Note that there may be a contrast among the darker inner and paler outer greater coverts reflecting an incomplete prealternate molt, but that this may be the case for Yellow-rumped Warblers of any age.

Photo by Marie-Anne Hudson, McGill Bird Observatory, May 2007

The outer rectrices (r3-r6) are relatively fresh, somewhat truncate and are dusky with moderate amounts of white. Note that the r1 feathers of this bird are particularly worn. This is understandable, as the prealternate moult does not include rectrices, and r1 tends to get the most exposure because of their position in the tail.

Photo by Marcel Gahbauer, McGill Bird Observatory, May 2005

Photo by Marie-Anne Hudson, McGill Bird Observatory, May 2007

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second-year male

Yellow-rumped Warblers undergo two moults (1^st prebasic and 1^st prealternate) before moulting their rectrices and tertials. Knowing this comes in very handy when ageing. This means that SY birds should have quite used-looking tails and tertials. SY males are bluish gray, often tinged brownish. The breast has a wide, complete or nearly complete black band. in the second photo below, the moult limits among the coverts are particularly distinct.

Photo by Marcel Gahbauer, McGill Bird Observatory, April 2006

Photo by Marie-Anne Hudson, McGill Bird Observatory, May 2007

Audubon's Warbler differs by having a yellow throat instead of white. Also, SY males tend to have less brown than do SY male Myrtle Warblers.

Photo by Manon Dubé, Banff National Park, May 2007

The outer primary coverts are narrow, tapered and relatively abraded. They are brown with little or no pale edging. Note that there may be a moult limit in the greater coverts on some birds (see first photo below), while others (as in the second photo below) have replaced all their greater coverts during their prealternate moult. In either case, the contrast between the unreplaced brown primary coverts and the newly replaced drusky greater coverts is very clear. Note also the contrast in colour and quality between the fresh inner greater coverts and the very worn tertials

Photo by Marie-Anne Hudson, McGill Bird Observatory, May 2007

Photo by Marcel Gahbauer, McGill Bird Observatory, May 2006

Photo by Marie-Anne Hudson, McGill Bird Observatory, May 2007

In Audubon's Warbler the unreplaced coverts tend to be more gray than brown, and there are fewer brown feathers among the median and lesser coverts and on the back. However, the moult limits remain visible, and the unreplaced and rather worn-looking tertials are a good indicator to use for SY birds.

Photo by Manon Dubé, Banff National Park, May 2007

The outer rectrices (r4-r6) are relatively abraded and tapered. They are a darker dusky tone in SY males than SY females and average slightly more white.

Photo by Marie-Anne Hudson, McGill Bird Observatory, April 2007

Audubon's Warblers tend to have more extensive white patches on the tail, as the two photos below illustrate, in comparison with the Myrtle Warbler above.

Photo by Manon Dubé, Banff National Park, May 2007

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second-year female

Yellow-rumped Warblers undergo two moults (1^st prebasic and 1^st prealternate) before moulting their rectrices and tertials. Knowing this comes in very handy when ageing. This means that SY birds should have quite used-looking tails and tertials. Female SYs are brownish and have brown auriculars, sometimes tinged gray. Breast has indistinct black streaking without a complete black band. Some may lack yellow crown and side patches.

Photo by Marcel Gahbauer, McGill Bird Observatory, May 2005

The outer primary coverts are narrow, tapered and relatively abraded. They are brown with little or no pale edging. The moult limit in the greater coverts is not as apparent as the SY male’s pictured above, but is visible nonetheless. As with males, SY females may replace all greater coverts during their prealternate moult (first photo below) or only some (second photo below).

Photo by Marcel Gahbauer, McGill Bird Observatory, May 2005

Photo by Manon Dubé, Banff National Park, May 2007

The outer rectrices (r4-r6) are relatively abraded and tapered. They are brownish with relatively small amounts of white.

Photo by Marcel Gahbauer, McGill Bird Observatory, May 2005

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after-hatch-year male

The upperparts are blue on AHY males, heavily washed grayish. The auricular is often mottled with black. The back feathers usually have distinct black centres.

Photo by Marcel Gahbauer, McGill Bird Observatory, October 2005

The greater coverts are black with a white fringe, the lesser coverts are edged bluish gray, and the primary coverts are broad, truncate and relatively fresh. They are dark with distinct grayish edging, and should not contrast in wear with the greater coverts. AHY-M wings are darker than those of AHY-Fs.

Photo by Marcel Gahbauer, McGill Bird Observatory, October 2005

The uppertail coverts have large black centres with bluish edging. The outer rectrices (r4-r6) are relatively broad and truncate. They are black with large amounts of white.

Photo by Marcel Gahbauer, McGill Bird Observatory, October 2005

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after-hatch-year female

Upperparts of AHY females are usually tinged bluish gray. The auricular is grayish without black mottling. The back feathers usually have small, indistinct black centres.

Photo by Marcel Gahbauer, McGill Bird Observatory, October 2005

The greater coverts are dusky with a whitish fringe, the lesser coverts are edged brown, and the primary coverts are broad, truncate and relatively fresh. They are dusky with distinct grayish edging, and should not contrast in wear with the greater coverts.

Photo by Marcel Gahbauer, McGill Bird Observatory, October 2005

The uppertail coverts are edged brown or a mix of brown and bluish gray. The outer rectrices (r4-r6) are relatively broad and truncate. They are dusky with moderate amounts of white.

Photo by Marcel Gahbauer, McGill Bird Observatory, October 2005

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hatch-year male

The upperparts of HY males are usually tinged bluish gray. The auricular is brownish without black mottling. The back feathers usually have small, indistinct black centres.

Photo by Marcel Gahbauer, McGill Bird Observatory, September 2005

The greater coverts are brownish with buff corners, the lesser coverts are edged bluish gray, and the primary coverts are narrow, tapered and somewhat abraded. They are brown with indistinct or no buffy edging, and should contrast with the greater coverts.

Photo by Marcel Gahbauer, McGill Bird Observatory, September 2005

The uppertail coverts are indistinctly centred black and are edged with a mix of brown and bluish gray. The outer rectrices (r4-r6) are relatively abraded and somewhat tapered. They are darker in HY males than HY females are average more white.

Photo by Marcel Gahbauer, McGill Bird Observatory, September 2005

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hatch-year female

The upperparts of HY females are overall brownish without gray. The auricular is brownish without black mottling. The back feathers usually have narrow, indistinct dusky centres. Essentially, HY females are as brown as Yellow-rumped Warblers get.

Photos by Marcel Gahbauer, McGill Bird Observatory, September 2005

The greater coverts are brown with buff corners, the lesser coverts are edged brown, and the primary coverts are narrow, tapered and somewhat abraded. They are brown with indistinct or no buffy edging, and should contrast with the greater coverts.

Photos by Marcel Gahbauer, McGill Bird Observatory, September 2005

The uppertail coverts are edged brown without bluish gray. The outer rectrices (r4-r6) are relatively abraded and somewhat tapered. They are dusky brown with small amounts of white.

Photos by Marcel Gahbauer, McGill Bird Observatory, September 2005

RETURN TO AGE/SEX OVERVIEW