Many More Molt Limits of Common Yellowthroats

 CAPTAIN SAMS

The slowdown continues. The station newly banded 24 birds today and recaptured 10.

Common Yellowthroats continue to visit our station. Since we are able to see so many in hand, I would like to take this opportunity to show even more preformative molt variations in this species. This will act as a sequel to my previous Common Yellowthroat molt limit post.

Common Yellowthroat (hatch year, unknown sex)

Some Yellowthroats may replace A2 (the lesser alula): A1 and A2 will have equally dark centers, and A3 will appear more worn, with brown centers similar to those of the primary coverts. The picture above shows an A2 limit: replaced alula feathers highlighted green, retained greater alula (A3) highlighted red.

Common Yellowthroat (hatch year, male)

This species may also show a primary covert limit. In this bird, the outer primary coverts are replaced (highlighted green). They are less worn, have darker centers and more vibrant edging compared to the retained primary coverts (highlighted red). Notice that in this individual, all 3 alula feathers are replaced, as their dark centers contrast with the brownish centers of the unreplaced primary coverts.

Common Yellowthroat (hatch year, male)

A bird with a primary covert limit may also have an eccentric limit. This picture is from the same bird as above. He has replaced the outer 7 primaries (p3 to p9). The inner two (p1 and p2) are retained, hence their browner rachis and more worn condition. 

Common Yellowthroat (hatch year, sex unknown)

You may also observe a limit either within the tertials or between the tertials and secondaries, as shown in the picture above. The replaced feathers (highlighted green) appear fresher and blacker.

Common Yellowthroat (hatch year, sex unknown)

Some birds may not have such an extensive preformative molt. The bird pictured above has 2 retained greater coverts with characteristic juvenile buff tips. The carpal covert, alula and primary coverts are also retained in this bird. They share the same brownish centers and worn condition as the buff-tipped greater coverts. The replaced coverts on the other hand (to the left of the retained greater coverts) look more black and vibrant.

Common Yellowthroat (after hatch year, male)

Finally, here is an example of an after hatch year bird's wing. All alula feathers are replaced and share the same dark centers as the primary coverts. Primary coverts look broad and have broad green edging. Primary feathers look broad as well and have a squared tip. There may be differences in rachis color and thickness, but it shows up as a gradient rather than sections of replaced vs. retained feathers.

— Jasmine

LITTLE BEAR

It was also a slow day out at Little Bear. We ended the day with 13 newly banded birds and 9 recaptures for a total of 22 birds of 9 species. The ocean was very hazy for most of the morning and some clouds rolled in and kept things from getting extra hot. Thank you clouds! A fun highlight from today was a Painted Bunting that we banded on our first day at Little Bear. He has had quite the glow up thanks to his prebasic molt. The technical term for this is delayed plumage maturation, when a bird retains it's juvenile plumage through the first breeding season. This strategy is more common in larger birds like gulls and raptors, but happens in certain songbird species too. Painted Buntings, American Redstarts, Orchard Orioles, and Blue Grosbeaks are a few. 

Painted Bunting (banded 8/22 as second year, unknown sex)

Painted Bunting (recaptured today, recorded as after hatch year male) 

We only have pictures of his wing, but you can tell he's much brighter and now has the characteristic blue head of adult male Painted Buntings. It's almost hard to believe it's the same bird! 

-Liz

Species	Captain Sam's		Little Bear
	New	Recaps	New	Recaps
Eastern Wood-Pewee	-	-	1	-
Traill's Flycatcher	1	-	-	-
White-eyed Vireo	-	4	-	-
Red-eyed Vireo	1	-	-	-
Northern House Wren	1	-	1	-
Carolina Wren	-	-	-	1
Gray Catbird	6	1	2	3
Swainson's Thrush	1	-	1	-
Ovenbird	-	-	2	-
Northern Waterthrush	1	-	1	1
Common Yellowthroat	10	3	4	-
American Redstart	-	2	-	-
Black-throated Blue Warbler	1	-	-	-
Prairie Warbler	1	-	-	-
Northern Cardinal	-	-	-	3
Painted Bunting	1	-	1	1

Today's Banding Stats	Captain Sams	Little Bear	TOTAL
# Birds Banded	24	13	37
# of Recaptures	10	9	19
# of Species	11	9	16
Effort (net-hours)	147.9	131.6	279.5
Capture Rate (birds/100 net-hours)	22.3	16.7	19.5
# of Nets	33	29	62

2026 Fall Cumulative Banding Stats	Captain Sams	Little Bear	TOTAL
# Birds Banded	2,444	1,333	3,777
# of Recaptures	334	160	494
# of Species	54	56	68
Effort (net-hours)	6,925.3	4,535.5	11,460.8
Capture Rate (birds/100 net-hours)	40.11	32.9	36.51
# of Days	47	40

Banding Staff

Aaron Given (CS)

Liz Held (LB)

Olivia DeMarchi (LB)

Jasmine Fu (CS)

Baxter Shirey (CS)

Note:  All banding, marking, and sampling is being conducted under a federally authorized Bird Banding Permit issued by the U.S. Geological Survey’s Bird Banding Lab.