JAEGERS 
215 
All birds of this order are protected by the Migratory Birds Convention 
Act and none of them may be killed legally in any part of the United 
States or Canada without special permission. 
Economic Status. Being sea birds, the damage they do ordinarily is 
slight and some of them are actively beneficial to man. 
FAMILY STERCORARIIDAE. SKUAS AND JAEGERS 
General Description. The skuas and jaegers are predaceous sea birds and as such 
have strongly hooked bills. The feet, webbed like gulls, are armed with small but sharp, 
strongly curved, raptorial claws. The skuas occur 
only in a single dark coloration, but the jaegers 
(except perhaps the Long-tailed) are dichromatic and 
show two distinct colour phases with various though 
less common intermediate stages between. The dark 
phase is almost evenly dark brown like the skua, 
but usually faintly lightening on the face and showing 
a suggestion of dark cap. The light phase has white 
or light underparts, often more or less crossbarred 
with dark, especially on flanks, throat, and cheeks 
(Figure 311), the latter as a rule with a golden tinge, 
and showing a distinct black cap. Young birds are 
usually in the dark phase and more or less completely 
barred with dark, or feather-edged with light. The species of this family are so similar 
to each other in coloration that the above is descriptive of all of them and they are almost 
inseparable by colour characters. 
Distinctions. The bills are diagnostic (Figure 311), there being a distinct nail at the 
tip forming a well-marked hook, plainly separable from the softer cere that occupies most 
of the upper mandible. This characteristic easily distinguishes them from the gulls, 
whereas the presence of nostril openings at base of the hook and two instead of three webs 
distinguishes them from the cormorants which have bills similar in general outline ( See 
Figures 94-97, pages 56-58). That the nostrils are not in tubes and are at the forward end 
of the cere instead of at the base of it, differentiates them from the shearwaters and 
petrels (Figures 83-88, pages 46-49) that also have hooked bills. 
Figure 312 
Wing of Jaeger, showing white at base of primaries; 
scale, about L 
Field Marks. Jaegers and skuas are sooty dark above and light or white below. 
In some all the body is evenly sooty in colour. Except the Long-tailed Jaeger all have 
a conspicuous light band (Figure 312) on the under-wing surface across the base of the 
primaries. They are very hawk-like in flight. Skuas are too rare with us ever to be 
recorded on sight evidence. The long central tail feathers (Figures 313-315) of the adult 
jaegers make good recognition marks. This characteristic tail is so conspicuous as to have 
suggested to sailors the colloquial names of “Mason” (referring to the trowel-like tail), 
“Hos’n” (from the tail like a marlin-spike, the special tool of a boatswain), or just “Marlin- 
spike.” 
Nesting. On the ground. 
Figure 311 
Jaeger, light phase; scale, 
