Update November 15 2004: added
nice dorsal shot by Lynn Barber, at bottom.
This 2CY Long-tailed Jaeger Stercorarius
longicaudus was photographed on the November 06
2004 pelagic out of South Padre Island, Cameron County, Texas:
The quickest way to age a dark-capped jaeger is to check the underwing
coverts; strongly-barred juvenile-type coverts indicate a 2CY
bird, while fully-dark, uniform coverts indicate an adult (but
may not preclude a subadult.)
Note the very limited, barely-present white at the bases of the
primaries, the thick bill with gonydal point half-way back, and
paleness of the adult-type gray upperparts. The central tail feathers
are 2nd-generation and thus pointed, not rounded at the tip as
on juveniles:-
Note below the lack of an obvious pale patch of feathers ahead
of the black cap at the base of the upper mandible - something
that non-juv. Parasitic almost always has:
Below note the pale blue legs (all jeagers retain black feet;
the two larger taxa develop mostly black legs after their first
year.) Note also that the black cap is cleanly demarcated from
the light cheeks and nape; Parasitic at this age tends to have
a less clean-cut boundary:
We came upon it as it was chasing this passerine (40+ miles out);
by the time we got close, it had killed it; we cruised up to the
corpse and confirmed the identity - an Eastern Phoebe:
