How to Identify Pomarine Jaeger Feathers

What Pomarine Jaeger Feathers Look Like

Pomarine Jaeger is the largest and heaviest-bodied of the three common jaegers, and its flight feathers reflect that bulk, running notably long and broad at about 8-10 inches. Upperpart feathers are dark grayish-brown to blackish-brown, fairly uniform. In light-morph adults, a dark cap contrasts with a pale, sometimes yellowish-washed collar and nape — check nape and collar feathers for this pale band. Underwing covert feathers, especially the axillaries ("wingpits"), show heavier, more extensive dark barring than the other jaegers — a genuinely useful diagnostic if underwing feathers are available. Central tail feathers in breeding adults are long, broad, and distinctively twisted with a blunt, spoon-like or paddle-shaped tip, unlike the pointed spike tips of Parasitic Jaeger or the very long thin streamers of Long-tailed Jaeger. Overall feather shafts are heavier and sturdier than the other two jaegers.

Step-by-Step: Is This Feather From a Pomarine Jaeger?

• Check central tail feather shape, if present. Broad, twisted, with a blunt or spoon-shaped tip is essentially diagnostic for an adult Pomarine Jaeger.
• Check underwing and axillary feathers for barring. Heavier, more extensive barring than Parasitic or Long-tailed Jaeger.
• Measure flight feathers. Notably large and broad, in the 8-10 inch range, reflecting the largest-bodied jaeger.
• Check overall shaft thickness. Heavier and sturdier than the other two species, consistent with a bulkier seabird.
• Check for a pale collar/nape band feather contrasting with a dark cap in light-morph birds.

Similar Species & How to Tell Them Apart

Parasitic Jaeger is smaller and lighter overall, with narrower flight feathers, lighter axillary barring, and (in adults) pointed rather than spoon-shaped central tail feathers. Long-tailed Jaeger is the smallest and slimmest of the three, with the least barred underwing coverts and, in adults, very long, thin, streamer-like central tail feathers rather than broad twisted ones, plus overall paler, grayer upperparts. Great Skua and South Polar Skua are much larger and bulkier still, with broad, blunt (not twisted) tail feathers and more prominent white patches at the base of the primaries than any jaeger.

Where & When You'll Find Them

Pomarine Jaegers breed on Arctic tundra, with breeding success tied to lemming cycles, and spend the rest of the year at sea, wintering well offshore in tropical and subtropical oceans and migrating along coastlines in spring and fall. Feathers are most likely found washed up on ocean beaches during migration periods, especially fall, when birds move along coastlines, or occasionally on the Arctic breeding grounds in summer near nesting territories in years of good lemming abundance.