Black-billed Cuckoo (Coccyzus erythropthalmus) Science Article 2
abstract
The vertical or perpendicular pose of the young Black-billed Cuckoo (Coccyzuse rythropthalmush) as been suggestedto function in concealing the young, implicitly from predators (e.g. Herrick 1910, Bent 1940). F. H. Kennard (in Bent 1940: 75-76) gives thefollowing description of a young Black-billed Cuckoo in this pose
SPENCER G. SEALY, The AUK, 102, 1985