wing length, third primary length, extent of white on the primaries, extent of white on the rectrices
, and tail length).
There was no statistical correlation between the estimated minimum age of individual birds and proportion of black tail rectrices in the total sample of 165 gannets ([r.
Neither in males nor in female gannets did the proportion of black rectrices in the full set of tail feathers correlate with concentration of head plumage pigments (as 4-AHP/PTCA, male [r.
Juvenile feathers in Thamnophilidae are distinct from subsequent plumages by having loosely textured feathers with lower barb densities than in subsequent plumages, having distinct coloration, and having distinct shapes with rectrices being more pointed and longer, greater coverts being shorter, and remiges being shorter (Dwight 1900, Zimmer and Isler 2003).
la, b); 2) partial, with replaced adult-like body feathers, lesser coverts, at least some or all median and greater coverts, and sometimes tertials or rectrices in both sexes (Fig.
When possible, when subsequently reviewing videos, the sex of adults was determined by the presence (male) or absence (female) of white outer rectrices
Nape, back, rump, and upper surface of rectrices
light olive-green, somewhat deeper on tail.
The small one had more downy plumage, including a wide black line extending from the crown to the nape, wing and rail feathers not fully developed, and the outer pair of rectrices
was chestnut in color in contrast to the other which had browner plumage (Fig.
In young cuckoos, the rectrices are grayish in areas where those of adults are black, the border between dark and white areas of the rectrices is less well defined, and the rectrices are more pointed than those of adults (Pyle 1997).
After the rectrices are replaced, all birds are aged as adults, so age ratios are invalid after December.
The preformative molt in HYs begins in breeding areas in early July and involves the body feathers but no tertials, rectrices or remiges (Pyle 1997); the adult prebasic molt begins in July and is a complete molt involving the entire plumage.
Red color in rectrices is only known from a bird with a left 4th rectrix heavily washed with red (Parkes 1993); however, since the feather was the only aberrantly-colored one (rectrices are grown simultaneously in the nest) and it had the broad shape of an adult rectrix rather than the narrower shape of the adjacent greenish rectrices, it was presumed to be the replacement of an accidentally lost rectrix.