Characteristics of Jaegers and Skuas
The sighting of any jaeger or skua can certainly add excitement to a
pelagic trip or seawatch. Five species are possible in North America and
the identification challenges endear them to veteran seabirders. They
are often seen at sea associated with gulls to which they are closely
related.They qualify as seabirds in this presentation because they spend
most of their time at sea except during breeding and because they are
usually seen in our area from pelagic trips. Most breed in loose
colonies, and show mate and site fidelity (except Pomarine Jaeger).
Females are larger than males.
They have strongly hooked claws like raptors and webbing between
their toes like gulls. They make extensive use of kleptoparasitism and
prey upon other seabirds at sea and on the breeding ground including the
world's most popular seabird, the puffin. These bully tactics do not
endear the skuas and jaegers to casual birders. They do not have a keen
sense of smell and find food by sight. This is why pelagic trips often
chum to attract gulls to the boat hoping to attract a jaeger or skua as
well. Unfortunately attracting gulls sends small Alcids away. If Alcids
are the target species do not attract gulls.
Male feeds the female before and after eggs are laid and continues to
participate in the feeding of the chick after hatching. Usually lay two
eggs with only one surviving especially in lean years. One chick hatches
before the other and is therefore bigger. In lean years this older chick
may eat the younger. Tundra breeding birds lose eggs and chicks to
Members of the family Laridae which
includes the gulls.
- Skuas and Jaegers
Genus Catharacta -Skuas
Skuas are primarily southern hemisphere breeders except for Great Skua
which breeds in the north east Atlantic. The skuas show less difference
in plumage between breeding and non-breeding adults. Adults tend to hang
around the breeding area rather than migrate long distances. In the
north Atlantic we are concerned with two species: The northern breeding
Great Skua and the southern hemisphere breeder the
South Polar Skua which spends the off season in the
Genus Stercorarius - Jaegers (Skuas in Europe)
This genus contains three species that all breed in the northern
hemisphere and are called Skuas in Europe and Jaegers in North
America. They are smaller than the Catharacta and migrate to the
southern oceans for the winter. Long-tailed Jaeger is a more
western breeder and infrequently seen in New England waters.
Pomarine and Parasitic Jaegers are seen in
small numbers on Stellwagen Bank and Jeffreys Ledge.
Why are Jaegers and Skuas so hard to identify?
Birds that exhibit many different plumages are always an
identification challenge. The skuas and jaegers show variation in
plumage in three circumstances.
Adults exhibit breeding plumage and non-breeding
· Young birds take several years to achieve adult
· Polymorphism - dark and light adult morphs
.When you are ready to tackle jaeger and skua identification you should
certainly purchase and study the book:
Skuas and Jaegers A Guide to Skuas and Jaegers of the World
by Klaus Malling Olsen and Hans Larsson. (1997)