We have been banding a bunch of Indigo Buntings lately so I thought it would be a good time to explain how we age and sex them. Hatch-year Indigo Buntings (and Painted Buntings) have a somewhat complex molt strategy. Their first prebasic molt starts almost immediately after they leave the nest. This molt consists of most or all of the body feathers and some wing feathers including lesser and median coverts but not the greater coverts, primary coverts, secondaries, and primaries. The resulting plumage is almost identical to the juvenal plumage and males and females look the same at this point. Later in the fall or winter, they undergo an extra molt (presupplemental molt) in which they replace the body feathers again along with more wing feathers including the lesser coverts, median coverts, greater coverts. In addition the outer 3-5 primaries and inner 3-4 secondaries are also replaced showing eccentric molt pattern. The resulting plumage is usually a little brighter than the previous plumage, and males and females still look similar. However, we should now be able to separate most males from females based on the amount of blue in the wing.
The photo below shows the wing of an hatch-year Indigo Bunting in its 1st basic plumage. Note that no greater coverts, primary coverts, secondaries, and primaries have been replaced. The unreplaced feathers are the same feathers that were grown in when the bird was in the nest. Males and females are indistinguishable when in this plumage.
Indigo Bunting (hatch-year, sex unknown) |
Indigo Bunting (hatch-year, probably female) |
Indigo Bunting (hatch-year, male) |
Adults do not undergo a presupplemental molt and will replace all of their feathers once in late summer during its prebasic molt. Adult females will look similar to hatch-year males and females except that the replaced primary coverts, primaries, and secondaries will be darker and have a slight blueish edging to them.
Indigo Bunting (after hatch-year, female) |
Indigo Bunting (after hatch-year, male) |
NEW BIRDS
1 Eastern Phoebe
1 Ruby-crowned Kinglet
74 Gray Catbird
1 Black-and-White Warbler
22 Common Yellowthroat
1 American Redstart
1 Northern Parula
2 Black-throated Blue Warbler
3 Palm Warbler (Western)
16 Yellow-rumped Warbler (Myrtle)
1 Swamp Sparrow
1 White-throated Sparrow
3 Indigo Bunting
1 Painted Bunting
RECAPTURES
1 White-eyed Vireo
1 House Wren
13 Gray Catbird
1 Black-and-White Warbler
2 Common Yellowthroat
1 Eastern Towhee
BANDING STATS
# of New Birds: 128
# of Recaptures: 19
# of Species: 17
Effort: 133.4 net-hours
Capture Rate: 110.2 birds/100 net-hours
# of Nets: 23
BANDING STAFF
Aaron Given
Mattie VandenBoom
Libby Natola
Matt Zak
William Oakley