Saturday, October 10, 2015

Aging Yellow-billed Cuckoos

Captain Sam's 

Things remained slow today at Captain Sam’s with 44 new birds and 25 recaptures, comprised of 16 species.  A cold front made its way through our area this afternoon, which should spark some movement overnight and hopefully bring us migrants for tomorrow.  Although it was slow, our day was made interesting by a visiting group of South Carolina Master Naturalists.  The Master Naturalists braved the mud and mosquitos for a glimpse at the banding process and were treated to an up close look at a Carolina Chickadee, a Painted Bunting, and many, many Gray Catbirds.    Sadly the group missed out on the best bird of the morning, our second of the season Yellow-billed Cuckoo.
South Carolina Master Naturalist Group

In the fall, the best ways to age a Yellow-billed Cuckoo is to look at the color pattern on the outer rectrices (tail).  On an adult, the outer rectrices will be blackish with a sharply defined white tip.  On a juvenile, the outer rectrices will be grayish with a less defined white tip.  Looking for this pattern is only useful in the fall because juveniles will replace their tail on the wintering grounds.  In the past we have mentioned that the color of the orbital eye ring could be helpful in aging cuckoos but this may not be the case for Yellow-billed Cuckoo.  Bright yellow orbital rings were thought to be a good indicator for younger birds but it seems that some adults can also have a bright yellow orbital ring instead of the dusky orbital ring that would be expected.  

Yellow-billed Cuckoo Tail (left: Adult right: Juvenile)


Little Bear
Little Bear remained close due to the flooding at the Ocean Course. 

  Species Captain Sam's Little Bear
New Recaps New Recaps
Yellow-billed Cuckoo 1 - - -
Eastern Phoebe 1 - - -
Red-eyed Vireo 1 - - -
Carolina Chickadee - 1 - -
House Wren 2 - - -
Veery 1 - - -
Gray Catbird 26 18 - -
Northern Mockingbird - 1 - -
Tennessee Warbler 1 - - -
Common Yellowthroat 4 - - -
Black-throated Blue Warbler 1 - - -
Palm Warbler (western) 5 - - -
American Redstart - 2 - -
Prairie Warbler 1 - - -
Northern Cardinal - 1 - -
Painted Bunting - 1 - -

 Banding Stats Captain Sam's Little Bear TOTAL
# Birds Banded 44 - 44
# of Recaptures 24 - 24
# of Species 16 - 16
Effort (net-hours) 127.5 - 127.5
Capture Rate (birds/100 net-hours) 53.3 - 53.3
Nets 25 - 25

Banding Staff
Aaron Given (CS)
Mattie VandenBoom (CS)
Chris Snook (CS)
Nancy Raginski (CS)
Sean McElaney (CS)
Casey Weissburg (CS)
Michael Gamble (CS)
Ryan Donnelly (CS)

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