i. Crimson tells you the male was singing.
Saturation in the cardinal's mantle deepens through the breeding spring, then dulls by August — pigment is a dated record, not a costume.
No. I
Cardinalis
ii. Slate is the warbler's working clothes.
Grey-blue dorsals hold the bird against bark and shadow; bright colour is a luxury, drabness is a survival decision drawn in pigment.
No. II
Dendroica
iii. Olive-yellow is rarely an adult.
Juvenile and female plumage runs warmer and quieter — confusing in the field, but the engraver's wash records the truth a name cannot.
No. III
Setophaga
iv. Black is the engraver's, not the bird's.
The mask, the eye-line, the rictal bristle — these are the engraver's deepest cuts, struck below the wash and immune to two centuries of fading.
No. IV
Halberd, sc.