[Ontbirds]Pomarine Jaeger ID at Barrie

Jean Iron jeaniron at sympatico.ca
Fri Nov 4 06:31:28 EST 2005

Several people asked us how to identify the juvenile Pomarine Jaeger at Barrie.

See photos http://jeaniron.ca/2005/jaeger.htm

Kevin McLaughlin calls it a typical "brown morph" juvenile Pomarine, the 
commonest form. He notes the overall look is the key and is made up of a 
number of points (see below) which do not support its identification as a 
Parasitic. We've added some comparisons of Parasitic in (parentheses) to 
Kevin's analysis.

- cold brown plumage (rusty feather edgings in most Parasitics)
- thick chested, size next to Bony impressive
- may have seven white primary shafts (fewer in Parasitic)
- short rounded projection of central rectrices (pointed central tail 
feathers in Parasitic)
- broad based wings though not real obvious
- broad white flash on bases of under primaries but only a bit of white on 
the bases of the greater under primary coverts; wear may be a factor (see 
paragraph below)
- stark white and brown barring on the undertail coverts along with whitish 
uppertail coverts (upper and undertail coverts less clearly barred in 
- no obvious streaking on the nape (head streaked on Parasitic)
- dark loral area an excellent feature as it contrasts to the pale bill base
- bill base is thick but not overly so
- remnants of whitish tipping on the coverts and no suggestion of whitish 
lines on the outer web of the greater coverts
- absolutely no pale or tawny crescents on the tips of the folded primaries 
(as in Parasitic)
- although looking rather "soft", the under wing coverts seem dark and 
white barred

We studied the Pomarine closely for several hours on Thursday. Although not 
obvious in the flight photos, we several times noted the double pale 
highlights on the underwings including the white area on greater under 
primary coverts which were more evident when backlighted. Many birders 
expect Pomarines to be bigger, but without direct comparisons with other 
jaegers their larger size and heavier bill are difficult to judge. However, 
its much greater size when pursuing Bonaparte's Gulls was apparent. In 
jaegers, females are slightly larger than males.

Jean Iron & Ron Pittaway
Toronto & Minden, ON

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