Numerous Gnatcatchers and a Lesson in Eccentric Molt

 CAPTAIN SAMS

It was another pretty warm and slow day out at Captain Sams. We ended the day with 10 newly banded birds and 5 recaptures of 9 species. Coincidentally, both stations caught their FOS Blue-gray Gnatcatcher at around the same time this morning. A few minutes after releasing ours, my phone beeped with a photo of a gnatcatcher sent by Liz at Little Bear. 

Blue-gray Gnatcatcher (hatch year, sex unknown)

                                         

These tiny, charismatic birds are especially charming during the spring and summer months when the males sport a very expressive, angry-looking unibrow as part of their alternate plumage. Aptly named, these birds snatch up small insects while flitting around on the branches of trees and shrubs. You will often see the flash of their white outer tail feathers as they hop around and flick their tail. They are also easily identified by their distinctive high-pitched and nasally call. Blue-gray Gnatcatchers aren't too common at Captain Sams, so catching this fellow during an otherwise slow morning was a treat!

--Olivia

 LITTLE BEAR

Today, we had 3 first of seasons: a Blue-gray Gnatcatcher, a Black-and-white Warbler and a Ruby-throated Hummingbird.

We also captured some molting Carolina Wrens. In the Southeast, Carolina Wrens will molt their flight feathers as a part of both the preformative and the prebasic molt.

The preformative molt occurs after the bird has fledged from the nest. Carolina Wrens will do an eccentric preformative molt. They will molt their body feathers, and some but not all of their flight feathers. The other feathers that grew in the nest will be retained. They will keep this set of formative and juvenile primaries for one year of life.

After a year, these birds will do a prebasic molt. They will replace all body and flight feathers. They will do this molt once a year for the rest of their lives.

Carolina Wren (left: hatch year, right: after hatch year, sexes unknown)

In the right picture above, the adult (or AHY) bird is performing its prebasic molt. It has replaced all outer primaries starting from p1. It is in the process of molting p6. Eventually, it will molt p7 to p10, as well as their other flight feathers. In contrast, the hatch year (HY) on the left did not start molting their primaries from p1. The bird is molting p3, p4, p5 and p6 (not visible from photo, as they are pin feathers). This bird is predicted to replace p7 to p10 as well, and maybe some inner secondaries over the next few days/weeks.

Carolina Wren (hatch year, sex unknown)
A closeup of 2 formative feathers (top) and 3 juvenile feathers (bottom).

Formative feathers are fresher and better in quality than the juvenile feathers. This is because young birds grow all of their feathers simultaneously in the nest (as they want to escape the nest as soon as possible). In contrast, formative feathers are grown sequentially, so the bird is able to expend more resources on each feather. We are able to tell the top formative feathers are fresher, newer and better in quality because the rachis color is darker. The barring is also bolder and denser. The juvenile feathers have a brownish rachis, and a lighter and sparser barring pattern.

-- Jasmine

Species	Captain Sam's		Little Bear
	New	Recaps	New	Recaps
Carolina Chickadee	-	2	-	-
Blue-gray Gnatcatcher	1	-	1	-
Carolina Wren	-	-	2	2
House Finch	1	-	-	-
Ovenbird	-	1	-	-
Northern Waterthrush	2	-	2	2
Black-and-white Warbler	-	-	1	-
American Redstart	1	-	-	-
Prairie Warbler	-	1	1	-
Northern Cardinal	1	1	2	2
Painted Bunting	4	-	4	1

Today's Banding Stats	Captain Sams	Little Bear	TOTAL
# Birds Banded	10	14	24
# of Recaptures	5	7	12
# of Species	9	7	11
Effort (net-hours)	137.61	86.8	224.41
Capture Rate (birds/100 net-hours)	10.9	24.2	17.6
# of Nets	33	28	61

2026 Fall Cumulative Banding Stats	Captain Sams	Little Bear	TOTAL
# Birds Banded	179	44	223
# of Recaptures	83	14	97
# of Species	24	12	25
Effort (net-hours)	1212.15	276.9	1489.05
Capture Rate (birds/100 net-hours)	21.61	20.9	21.26
# of Days	10	3	10

Banding Staff

Aaron Given (CS)

Michael Gamble (CS)

Liz Held (LB)

Olivia DeMarchi (CS)

Jasmine Fu (LB)

Aiden Gifford (LB)

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.